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PROGRESSIVE SERIES VOLUME I 
 
 PRACTICAL MANUAL OF 
 DENTAL CASTING 
 
 BEING THE 
 RECORDED EXPERIENCES OF 
 MANY ABLE AND EMINENT MEN 
 IN THE DENTAL PROFESSION 
 
 Profusely Illustrated 
 
 Reprinted from THE DENTAL SUMMARY, 1909-1913 
 
 SECOND EDITION 
 REVISED AND ENLARGED 
 
 Published by 
 
 THE RANSOM & RANDOLPH CO. 
 
 Toledo, Ohio 
 
 1913 
 
m^^ 
 ^^t 
 \(^i^ 
 
 Copyright, 1913 
 
 BY 
 
 The Ransom & Randolph Co. 
 
 Printed by 
 
 The Express Publishing and Printing Co. 
 
 Toledo, Ohio 
 
 1913 
 
»»< 
 
 PREFACE 
 
 IN PREPARING THIS BOOK and offering it to the dental 
 profession, the sole object has been to place within easy and 
 convenient access, in concise, permanent form, the best 
 thoughts of the most expert and successful casting men, together 
 with records of their results, as they have been expressed through 
 the pages of The Dental Summary during the past three years. 
 
 To this has been added historical articles, covering the 
 origin and progress of the casting art as applied to dentistry, 
 showing, step by step, the really wonderful advancement that 
 has been made and the immense usefulness of that art to the 
 dental profession. 
 
 The book will be found in line with mocern methods. Every 
 phase of the casting process has been touched upon, some of 
 them worked out exhaustively; and, in its pages, will be found 
 much practical advice and instruction that cannot fail to be help- 
 ful to all, while, for the beginner, it would seem to be altogether 
 invaluable. 
 
 The idea of profit has not been considered by the publishers. 
 The price at which the book is offered ought to convince even,'- 
 one of that fact. The preservation of the knowledge contained 
 therein and the placing of that knowledge in the hands of the 
 profession has seemed a sufficiently high ideal of service to warrant 
 the labor and expense involved. 
 
 The Publishers. 
 
PRACTICAL MANUAL 
 OF DENTAL CASTING 
 
ANCIENT ORIGIN OF DENTAL CASTING 
 
 By L. W. Strycker, New York. 
 
 The object in preparing this article is not to change public opinion nor to bring 
 discredit upon anyone. Rather is it to enlighten the dental public upon a subject con- 
 cerning which much erroneous information is extant, in the hope that others may 
 take up the subject and work it out for the benefit of all, as did the Old Masters in 
 an age when time was nothing and art everything. 
 
 The facts herein laid before the public have been gained by the study of old 
 text-books as well as from the references to current authorities that are given. 
 Being in possession of this knowledge, the writer looks upon it as his duty to give it 
 out. By withholding it, he would lay himself open to the charge of secretiveness, 
 and bring dishonor upon himself in later years. 
 
 Of course, only the most brief outline can be given in such an article. Any at- 
 tempt to print all of the valuable information that has been gained by this investiga- 
 tion would be entirely out of the question, as volumes would be required to reproduce 
 it. The books themselves should be read by every man who is interested in the 
 subject sufficiently to take the time necessary. For those who have not the time 
 at their disposal, this brief resume has been prepared, and is here offered for what it 
 may be worth to the profession. 
 
 Fig. 1 — " Malaga a la Francaise," or 
 piece casting. The model com- 
 pleted. 
 
 Fig. 2 — Piece casting; the model 
 "inverted." 
 
 The most cursory investigation of the authorities given will convince any man 
 that casting by the so-called "modern" processes is by no means new; that it is 
 simply a neglected and almost forgotten art. In taking up the subject we must go 
 hack to the most ancient text-books and records, the older the better. The methods 
 that we are now so eager to learn arc handled by the Old Masters in the founding art 
 with most satisfactory clearness and particularit\- of detail. Kspeciall\' is this true 
 of the "Cire Perdue" or disappearing model or "wasting wax" proc-ess, which was 
 known and in common use almost countless ages ago. 
 
6 PRACTICAL MANUAL OF DENTAL CASTING 
 
 This also is true of two of the methods for forcing the metal into the mold in 
 common use today — centrifugal force and pressure. The centrifugal method is 
 first mentioned in the old books, and we reproduce an illustration of one of these 
 ancient centrifugal casting machines (Fig. 4). This was used for casting bronze 
 busts and other objects of art. 
 
 Later the mechanical pressure air-pressure machines were invented and became 
 well known. Illustrations are given of these ancient devices (Figs. 5 and 7). 
 
 The earliest account of the casting of bronze by the cire perdue or disappearing 
 wax model process is given in Knight's American Mechanical Dictionary as 22.30 B. C, 
 and has to do with a reference by Herodotus and Diodorus to massive bronze statues 
 that were set up in the Temple of Belus, in Babylon. 
 
 Fig. 3 — "Cire Perdue," or Waste- 
 Wax Method. Identical with 
 Modern Disappearing Model 
 Methods. 
 
 Fig. 4 -Ancient Centrifugal Casting 
 Machine. Date unknown. 
 
 In Isaiah, xliv, 12, written about 712 B. C, is an account of the making of the 
 golden calf by Aaron, supposed to be several centuries earlier, or about 1491 B. C. 
 "He," Aaron, "received then the golden ear-rings of the people at their hands, and 
 fashioned it with a graving tool, after he had made of it a moulten calf." 
 
 The Colossus set up by Nero the Roman emperor, before his golden house, 
 near the site of the Temple of Venus at Rome, was a bronze figure of himself, the work 
 of Zenodorus. This was also cast by the cire perdue, or disappearing wax model 
 process. — Knight's American Mechanical Dictionary. 
 
 Myer's Ancient History tells us that bronze was cast by the Greeks about the 
 eighth century B. C, which also speaks of Lycippus as being renowned for his works 
 in bronze. 
 
 This knowledge, that the ancients were in possession of the greatest skill in the 
 art of casting metals, lets a flood of light in upon some of their most famous produc- 
 tions now preserved in museums. Until this was learned concerning them, the 
 wonder was how such marvelous reproductions could have been made with the 
 crude methods supposed to be at their command. The use of the disappearing 
 wax model, invested and cast upon a large scale, it is true, but in precisely the same 
 manner as that now employed in dentistry, makes all that clear. 
 
 "The great bronze lions of the Nelson Monument in London are a sad example 
 of the present low state of the founder's art. Coarse sand casting in England now 
 takes the place of the delicate cire perdue process." — Encyclopedia Brittannica, 
 Vol. 14, page 79. 
 
Ancient origin of dental casting 7 
 
 The full-length recumbent effigies of Henry III and Queen Eleanor at West- 
 minster, cast in bronze by this process (disappearing wax model method) are equal, 
 if not superior, in artistic beauty to any sculptor's work of the same period." (End 
 of the thirteenth century.) — Encyclopedia Britlannica, Vol. 14, page 77. 
 
 "The great candelabrum in Seville cathedral is the finest specimen of sixteenth 
 century metal work in Spain. It is mainly the work of Bart Morel, in 1562. It is 
 cast in bronze, enriched with delicate scroll-work, foliage and numbers of well- 
 modeled statuettes, cast by the disappearing wax model method." — Encyclopedia 
 Britlannica, Vol. 14, page 76. 
 
 "In Work-Shop Receipts," published by E. Spon, London, page 221, is de- 
 cribed the two methods of wasted-wax casting: 'Malaga a la Francaise,' or piece 
 casting. (See Figs. 1 and 2.) The other process is that known as cire perdue, or 
 waste-wax pattern. It is the more ancient of the two and has been practiced from 
 time immemorial by the artists and artizans of Italy." (See Fig. 3.) 
 
 "The mention of molds for the casting of wax figures is ascribed to Lysistratus. 
 about 328, B. C." — Knight's American Mechanical Dictionary, Vol. 2, p. 1459. 
 
 "Suppose a small ornamented vase were to surmount the pillar; the founder 
 would prepare the pattern for this in a more elaborate manner. He would first 
 mold it in wax." — Chambers' Encyclopedia, Wo\. 4., p. 454. Published 1870. 
 
 "An old method which is still employed in Italy is to make a core composed of 
 potter's clay, brick dust, cow's hair or some other composition, and over this to model 
 the figure in wax; then the other mold is formed on this of some composition of 
 which loam is the principal part. The whole is then dried, and baked, in an oven, 
 until the wax is melted and cleaned, and the mold is rendered sufficiently porous." — 
 Amn. Cyclopedia, \o\. 4, p. 85. Published 1S75. (The italics are mine.) 
 
 Fig. 5 — Pressure Casting Machine, 
 about 1819. 
 
 Fig. 6 — Type Casting Macliine. 
 Casts by pressure. 
 
 "Castings of great delicacy are produced by using models of wax. These are 
 embedded in molds of finely-ground earth, which are then heated red hot. The mold 
 is baked and the wax disappe.a.rs; and the metal, when poured, exactly takes its 
 V\2ice."— Knight's Amn. Mech. Diet., \'ol. 1. Published 1880. 
 
 The most clearly written directions for using the disappearing wax model 
 method are given on page 72, \o\. 14, Enc. Brit., published in 1891, h\ R. S. Peale 
 Co., Chicago. These directions were reproduced almost word for word, sufficiently 
 so to warrant the assertion that they are identical, in the first directions given to us 
 for the casting of inlays and the like; particularh- where we are told to "use an in- 
 vestment mixed with water to the consistency of cream, and apply with a brush, 
 until a coating is formed over the wax," etc. Here is the quotation: 
 
8 PRACTICAL MANUAL OF DENTAL CASTING 
 
 "methods ok manipulation in metal work. 
 
 "Gold, silver and bronze may be treated in various ways, the chief of which 
 are (I) casting in a mold, (2) treatment by hammering and punching (swaging; 
 French repousse). The first of these, casting, is chiefiy adapted for bronze, or in 
 the case of more precious metals, only if they are used on a very small scale. The 
 reason for this is that a repousse relief is of much thinner substance than if the same 
 design were cast, even by the most skilful metal worker, and so a large surface may 
 be produced with a very small expenditure of valuable metal. 
 
 "Casting is probably the most primitive method of metal work. This method 
 has passed through three stages, the first being represented by solid castings, such as 
 are most celts and other implements of prehistoric times; the mold was formed in 
 clay or stone, and the fluid metal was poured in until the hollow was full. The next 
 stage was, in the case of bronze, to introduce an iron core, probably to save needless 
 expenditure of the more valuable metal. The British Museum possesses an inter- 
 esting Etruscan or archaic Italian example of this primitive device. It is a bronze 
 statuette from Sessa, on the Volturus River, about two feet high, of a female, stand- 
 ing, robed in a close-fitting chiton. The presence of the iron core has been made 
 
 Fig. 7 — Dr. Carroll's Air Pressure 
 
 Casting Machine, 188.5-6. , 
 
 visible by the splitting of the figure, owing to the unequal contraction of the two 
 metals. 
 
 "The third or last stage in the progress of the art of casting was the employment 
 of a core, generally of clay, around which the metal was cast in a mere skin, only 
 thick enough for strength, without waste of metal. 
 
 "The Greeks and Romans attained to the greatest po.ssible skill in tliis process. 
 Their exact method is not certainly known, but it appears probable that they were 
 acquainted with the process now called cire perdue (wasting wax method), the same 
 as that employed by the great Italian artists in bronze, and still unimproved upon, 
 even at the present day. Cellina, the great Florentine artist of the sixteenth century, 
 has described it fully in his Trattalo delta Scultura. If a statue were to be cast, the 
 figure was first roughly modeled in clay, only rather smaller in dimensions than the 
 future bronze; all over this a skin of wax was laid and worked by the sculptor's 
 modeling tools to the required form and finish. A mixture of pounded brick, clay 
 and ashes was then ground finely in water, to the consistency of cream; and 
 successive coats of this mixture were then applied -ivilh a brush, imtil a second skin 
 was formed all over (he wax, fitting closely into every line and depression of the 
 modeling. Soft clay was then carefully laid on to strengthen the mold, in con- 
 siderable thickness, till the whole statue ajjpeared like a shapeless mass of clay, 
 around which iron hoops or rings were bound to hold it all together. 
 
ANCIENT ORIGIN OF DENTAL CASTING 9 
 
 " THl' whole was iheii tlioroui^lil}' drifl and placed in a liol own, which baked 
 the clay, both of the core anrl the outside nujld, and mki.TEI) THE wax, which was 
 allowed to run oLit through small holes made for the |Hiri)ose. The mold was now 
 ready for casting," etc. 
 
 So here we have a fairly accurate and connected history of the disappearing 
 MODEL procp:ss, and will next take up casting machines in the use of which pres- 
 sure was employed. 
 
 Our cut, Fig. 4, shows a primiti\e centrifugal machine, used for casting a bust. 
 
 Knight's Amn. Mech. Diet., Vol. 1, published 1880, says: "In the English 
 patent, No. 3197, January 28, 1809, the molds for casting are upright and are made 
 to revolve on pivots or spindles. The centrifugal force causes the metal to fill up 
 all parts of the mold." It also says: " In an American patent of 1857 the car wheels 
 are revolved (while being cast) so that the first metal poured is made to forrn the 
 tread of the wheel, and the second portion to form the body of the wheel," and further: 
 "In Bessemer's patent the metal is poured into fast-revolving cjdinders, the rapid 
 rotation of which causes the metal to collect on the inside of same, when it is allowed 
 to cool. It is then split open and rolled." 
 
 The same volume then speaks cf pressure casting machines. "To obtain the 
 best results in compact metal castings, destitute of porcsity, and with sharp defini- 
 tion on the angles and ornaments, casting under pressure has been devised. See 
 Hollingrake's English patent, 1819." 
 
 Following this it gives a drawing of the machine, which we ha\"e reproduced as 
 Fig. 5. Going farther, it says: 
 
 "In one case the molds are so arranged that the top part serves as the follower 
 of a press, and is operated on by screws. The top part tits closely into the matrix 
 and is provided with ingates for the metal, which are closed by slides when the mold 
 is full. The pressure is applied to the metal while in a melted state, with sufficient 
 force to expel the air and gas from and solidify the metal.'' 
 
 Then it speaks of Smith's process of compression casting. The face of the article 
 is covered with a preparation of potter's clay, the model is withdrawn by a little 
 india-rubber suction apparatus, "and we have an exact fac-simile, ready, when dried, 
 to be cast from. Nothing can exceed the beauty of the result by casting the metal 
 under pressure in the mold. Thus prepared, screws and nuts which never had a 
 tool put on them, lea\e nothing to be desired in the way of accuracy- and com- 
 pleteness." 
 
 On page 604, describing the term "compression-casting," we find this: "A 
 mode of casting bronzes, etc., in molds of potter's clay, under a pressure which causes 
 the metal to flow into the delicate tracery left by the pattern. This work nearly 
 approaches the work of the graver and chisel. It is especially used in casting house- 
 builders' hardware, letters, numbers for houses, etc." 
 
 In Vol. 2, page 1462, is the following: "Soft and perishable objects -may be 
 so molded as to produce a single casting by one of the several following methods, 
 which are adapted to the procuring cf castings cf small animals, insects, flowers, 
 feathers, ferns, sea- weed, wax models, etc: 
 
 1. Support the tibject in the center of a small iio\, by needles; one or two 
 should be sufficientK' largi' to form ingates. l-'ine ri\ir mud is dropped into the box 
 and shaken around so as to adheri' to tin- object. When partialK' dr\-, a coarser 
 grade of silt is thrown in until the box is filled. The needles and ingate wires are 
 
10 PRACTICAL MANUAL OF DENTAL CASTING 
 
 withdrawn, the meld burned to reduce the object to ashes, which are shaken or 
 blown out, when the mold is ready for casting. 
 
 2. Another method is to take the object itself or a wax model, such as that of a 
 flower, and suspend it in a box while plaster of Paris is carefully poured around it. 
 The application of heat causes the object to burn or the plaster to absorb the wax; 
 or, if the latter be in excess, it may be poured out. The strings by which the object 
 was suspended are withdrawn and the mold is ready for casting. This plan was 
 adopted in casting the feather of the equestrian statue of George III, at Pall Mall, 
 London; and specimens of ears of wheat, flashy flowers, such as coxcomb, and other 
 beautiful objects." 
 
 We are indebted to the Italians and French of the fifteenth, sixteenth and seven- 
 teenth centuries for safe molds; the ones mentioned above are termed waste molds. 
 
 On page 2312, Vol. 3, this work describes the casting of busts and statuary. The 
 print is very fine and the article would fill a single issue of anj' of our dental journals. 
 The article was written in 1844. The description in part follows: 
 
 "The present system of statuary casting is as follows: 
 
 1. Take a cast in plaster sections, which together form a matrix. 
 
 2. Cover the inside of these sections with a shell of wax. 
 
 3. Place the sections together so as to form a mold. 
 
 4. Fill the inside with cla^' or slush, so as to form a core with supports to sus- 
 tain it independently of the mantle. 
 
 5. Remove the plaster sections, the wax adhering to the clay. 
 
 6. Work up the wax surface into complete form by hand. 
 
 7. Coat with porous clay composition to form mantle. 
 
 8. Bake in a furnace, melting or burning out the wax. 
 
 9. Run the metal into the baked clay mold. 
 
 The church of St. Isaac at St. Petersburg is decorated with a large number of 
 statues and figures in relief obtained by this process." 
 
 On pages 2674-2675, Vol.3, the type-casting machine is described, showing the 
 Bruce machine, and says that in 1850 a French invention by M. Didot was designed 
 to cast about 200 types at once, requiring about twenty seconds. Pressure brought 
 to bear upon the mclten metal forced it into all the recesses of the molds. 
 
 Westcott's machine, U. S. patents 115, 796, June 6, 1871; 169215 and 169216, 
 October 25, 1875, casts and sets the type by pressure on the molten metal. 
 
 In the American Cyclopedia, Vol. 13, p. 791, published 1875, we find the follow- 
 ing: "There are difficulties in making large, thin vases, which have been overcome 
 at Sevres by the employment of atmospheric pressure and exhaustion. A plaster 
 mold is used, and the cast is made either by covering the mouth of the mold and forc- 
 ing air into the interior, or by exhausting the air through the porous plaster by means 
 of an exterior air-tight case." 
 
 The Century Dictionary and Cyclopedia, Vol. 1, p. 849, published 1889, in de- 
 scribing the meaning of the words "Compression Casting," uses these words: "A 
 method of casting in molds of potter's clay, with sufficient pressure to force the metal 
 into the most delicate tracery left by the pattern. It is used in casting letters, 
 stamps, house numbers, house builders' hardware, etc." Further on it defines the 
 meaning of the words "Casting Press" as "a press in which metal is cast under 
 pressure." 
 
 Chambers' Encyclopedia, Vol. 9, p. 606, published 1870, says that various at- 
 tempts were made during the early part of the century to cast type by machinery, 
 
ANCIENT ORIGIN OF DENTAL CASTING 11 
 
 but that the first successful type-casting machine was invented h\ David Bruce. 
 Jr., of New York, and patented March 17, 1838. 
 
 The first type-casting machine was patented in the United States in 1828 by 
 William M. Johnson, but it did not produce good types. The patent was sold to 
 George Bruce, and the machine was used by him until 1845. David Bruce mean- 
 while patented another machine, 1843, with improvements two years later, which 
 gave entire satisfaction and is now in general use in American type foundries. 
 
 This same volume gives an illustration of a type-casting machine, and describes 
 it as follows: 
 
 "A type-casting machine consists first of a small melting-pot, which contains 
 the molten metal. In the interior of the pot is arranged a forcing pump and a 
 valve for admitting the metal under the piston, and also for preventing of the return 
 of the metal into the mass in the pot when the piston is depressed, and thus securing 
 the full force exerted upon the piston being transmitted by the piston to the molten 
 metal under it, and forcing it through a narrow channel to the mould," etc. 
 
 The Century Dictionary, Vol. 3, p. 2531, in describing pressed glass, says: "Glass 
 while in a molten state, is brought to shape in a mold by a plunger." 
 
 The Encyclopedia Brittannica, 9th edition. Vol. 18, p. 481, describes a method 
 of casting steel ingots employed by Sir Joseph Whitworth, by applying hydraulic 
 pressure to the metal in the mold until it solidifies, which "has been adopted by the 
 inventor with great success in the prevention of blow-holes and similar imper- 
 fections." 
 
 Now, let us see what all this has to do with dentistry. (See Fig. 7.) This 
 illustration shows a machine devised by Dr. C. C. Carroll, cf Meadville, Pa., in 
 1885 or '86, for casting plates by the pressure process. Dr. Carroll turned o\er his 
 invention unreservedly to the profession, the following paragraph appearing in the 
 copy of Directions given with the machine: 
 
 "These goods are placed before the profession on their merits, upon the most 
 liberal terms, without any charge of license or royalty upon the patents by which 
 they are covered, and by the use of which all other patents for crowns, bridges, etc., 
 are evaded." 
 
 He also gives full directions for casting, and says: "Maintain the pressure 
 about five seconds to give the molecules of metal time to arrange themselves under 
 pressure. Otherwise there may be small pits over the surface of the denture." 
 
 He further says: "Mold upon the teeth in thin paraffine wax the crown or 
 bridge that is intended to be worn," etc. It seems fair to assume that he made his 
 abutments and no doubt his inlays in the same manner. 
 
 Now, let us turn to periodical literature on the subject: 
 
 In the account of the meeting cf the First District Dental Society, State of New 
 York, Tuesday evening, March 13th, 1894, at the New York Academy of Medicine, 
 published in the Dental Cosmos, Vol. 36, No. 5, May, 1894, appears the following: 
 
 "Dr. George F. Reese, of Brooklyn, N. Y., demonstrated the method of adjust- 
 ing his gold alloy cast crown: 
 
 "A right superior lateral root was selected in a lady patient. He had the root 
 already prepared; then the artificial crown, which was a plain rubber tooth, was 
 ground to fit to the root and gum; next a piece of placinum wire, coated with gold 
 the length cf the rcot, was hammered flat at the exposed end and bent into a foot 
 shape. It was then fastened by wax to the artificial crown and an impression of 
 the root was taken. This was put in and remo\'ed a number of times, the surplus 
 
12 PRACTICAL MANUAL OF DENTAL CASTING 
 
 taken off with a heated spatula until adaptation and contour were correctly ob- 
 tained, down to the finest detail. It was then placed in cold water to harden the 
 wax and tried in again. Everything being found satisfactor}', two points of wax were 
 put on the back of the crown, which was then invested in plaster of Paris. After 
 hardening the wax was grooved out, the matrix heated, and the wax melted out by a 
 fine stream of boiling water. Two pockets were then made, one being the pouring, 
 the other the vent gate. This was again invested in plaster, which was now ready 
 after hardening and standing a couple of hours to be put in the drying oven. When 
 dry, which is shown by the mirror test, the gold alloy was melted and heated until 
 it turned a purplish tint, when it was ready to cast. 
 
 "The doctor, after finishing, proceeded to insert a duplicate crown. By so 
 doing it was shown that the crown fitted perfectly. He then permanently fastened 
 it by drying out the root and coating the crown root with oxyphosphate cement." 
 
 Page 269 of the April, 1889, Dental Cosmos, shows us the following: "Dr. 
 Reiss, of Brooklyn, showed a specimen of an improved porcelain crown." 
 
 Page 293, same number: "Dr. J. N. Crouse, by permission, called attention 
 to the Dental Protective Association. He said that it was necessary to act at once, 
 as they must have money now to carry on the fight against The Tooth Crown 
 Company." 
 
 In concluding I wish merely to say that I believe in giving credit where credit 
 is due; and that to me it seems chat credit is, in this case, undoubtedly due to the 
 man who devised the crown and bridge that has stood the test of time, and promises 
 to stand indefinitely, rather than to one that has done nothing more than to revive 
 an art that has been practiced in all branches of metal work from time immemorial, 
 that probably is as old as man's knowledge of metals, and for which, at this late 
 day, great claims for originality are made. 
 
 As to the kind of work that is being done in dentistry along that line, the average 
 result is described by Dr. Rhein, of New York, who, at a recent dental meeting, 
 spoke of the average inlay as "A floating island of gold in a sea of cement." 
 
 Unless the average practitioner shall learn speedily to cast better inlays and 
 insert them with greater skill, there most certainly is grave danger that the inlay 
 method will bring discredit upon the entire profession. 
 
 EARLY ATTEMPTS AT INLAY CASTING 
 
 By C. V. Vignes, D.D.S., New Orleans, La. 
 
 Some four years ago, before the present methods of gold inlay casting came in 
 vogue, and before I had heard of cast gold inlays, I made some attempts at casting 
 gold in a mold, a description of which I bslieve will be of interest. 
 
 While the method I used was somewhat different from that now employed, and 
 while I was to a great extent unsuccessful, yet I was fortunate enough to cast a 
 fairly good inlay. And having been so close to the right way, I feel pardonably 
 proud of the pioneer work that I did in that direction, although it was abandoned as 
 impracticable, even unsuccessful. 
 
 Working upon the idea that the duplicating in gold of wax models of missing 
 parts of teeth would greatly facilitate our work, I made the following experiments 
 with the doubtful success above mentioned: 
 
 After obtaining an impression of the cavitj' in pink paraffin and wax and carving 
 to contour, as is at present done with the special inlay wax, I attached a small rope 
 
EARLY ATTEMPTS AT IXLA ]' CAS'J-JNG 13 
 
 of the sanif material tcj tlie model to form a sprue, and proceeded to imest the case. 
 The investment was made small and without the ring that is now used in investing 
 inlay cases. After the setting of the investment, a funnel-shape depression was made 
 around the sprue. 
 
 So far I was on the right road to the successful casting of the gold inlay; but my 
 idea of the sprue was not to force the melted gold through it, nor was the carved 
 funnel leading to the sprue to be used as a crucible in which to melt the gold prior 
 to its being forced into the matrix formed by the disappearance of the melted model; 
 but the funnel and sprue were made to facilitate the working into the matrix of gold 
 filings. My idea being that if I could fill the matrix with gold filings and heat the 
 investment (which was, for that purpose, made ver\' small) to the melting point of 
 gold, that I would attain the result sought for; but in this I was mistaken, for I 
 succeeded only in obtaining a globule of gold. 
 
 Following up the first idea, I thought that if I could put a gold lining on m\' 
 model that I would meet with ultimate success. To do this in a simple manner and 
 to obviate the necessity of burnishing foil into the cavity, after obtaining my model, 
 I rolled it into gold filings, reinserted it into the cavity, reburnished it and proceeded 
 as before. By this method I was more successful than in my first attempt. Failure 
 was due to the fact that not enough of the gold filings investing the model would 
 adhere to the investment to give the complete metallic lining looked for. The 
 casting, while it had the general shape of the cavity, w-as too defective to be put to 
 practical use. Hence the abandoning of the idea. 
 
 TECHNIC OF A CAST GOLD INLAY 
 
 By A. F. Miller, D.D.S., Sandusky, Ohio 
 
 A cavity in the disto-occlusal surface of an inferior, right first molar was prepared 
 for a cast gold inlay in the following manner: The disto-buccal and disto-lingual 
 margins extended to beyond the point of contact. All sharp angles and margins 
 removed, except the gingival portion at which point the surface was dressed oflf with a 
 fine grit, hard rubber safety, separating disk. This disk being flexible can be extended 
 under the free margin of the gum with little discomfort to the patient. Excavation 
 was extended to the occlusal center, cutting out the sulcus where carious and so 
 formed that the wax impression can be freely withdrawn. The above method of 
 cavity formation presents two advantages: first, as retaining points for the inlay; 
 second, the removal of all sharp angles and margins that would be broken down in 
 the mold by the action of the cast metal against them, thus preventing proper adapta- 
 tion of the inlay to the cavity. This cause is often erroneously attributed to shrink- 
 age or expansion of the metal. Gently w^arm the wax for the impression over a 
 flame and press it into the cavity with the finger or flat burnisher, instructing the 
 patient to close the mouth for occlusion. Trim off all excess contouring where in- 
 dicated, burnishing the wax over the approximal edges and carving flush to the oc- 
 clusal margins. Chill the wax and carefully remove from the cavity with a small 
 excavator. Carve a horizontal groove in the wax to give vertical anchorage to 
 the inlas'. This can be done more conveniently after the sprue wire is inserted. 
 Heat and insert sprue wire in the approximal aspect of the model and secure it in 
 its position in the sprue former with the point of a wooden tooth pick. 
 
 The first investment consisted of a small quantity of the Detroit investment 
 compound applied with a soft hair brush, covering the model uniformly to about 
 
14 PRACTICAL MANUAL OF DENTAL CASTING 
 
 1-8 inch thick, extending it down over the sprue former. This is then invested with 
 a second mixture of equal parts of 3'ellow molding sand and plaster, a little sodium 
 chloride added to hasten setting, and flasked in a split rubber tube secured from 
 spreading at the bottom by the flange at the sprue former and by an open metal ring 
 at the top. 
 
 After setting, the flask is removed and the wax and moisture eliminated by 
 laying the investment horizontally on a wire screen over a flame on a case-heating 
 stove and applying the brush flame from the blow-pipe on and over the end opposite 
 the gate. This procedure required only fifteen minutes from the cime the invest- 
 ment was set, including the casting; the inner investment showing no appreciable 
 change from the high temperature to which it was rapidly subjected. 
 
 It is claimed by the demonstrator that the outer investment serves as a pro- 
 tective envelope to the inner against unequal expansion or contraction, thus result- 
 ing practically in an inlay uniform and without shrinkage. 
 
 The instruments used in preparing the cavity were Black's rapid excavator 
 chisels, a German short, right angle, fissure bur, two sizes, and fissure stone for 
 right angle. 
 
 The inlay was cast on a vertical centrifugal casting device designed by the 
 demonstrator. 
 
 The inlay was seated, and cemented in the cavity to which it showed perfect 
 adaptation at every point. 
 
 PORCELAIN CROWN WITH CAST GOLD BASE 
 
 By W. A. Sanderson, D.D.S., Pittsburgh, Pa. 
 
 To make a porcelain crown with a cast gold base, proceed as follows: 
 
 Select a tooth of any make desired, either fixed or detached post. 
 
 Prepare root in usual manner, with a short bevel in labial, and a longer bevel 
 in palatal direction. Grind crown roughly to place, leaving plenty of space between 
 the crown and the end of the root on the palatal side. Mold a small piece of soft inlay 
 wax about the pin and press to place or nearly so. Remove and trim away surplus 
 wax. Warm slightly and press home. After again removing, be careful to remove 
 all wax from face of porcelain, wipe it away with cotton saturated with alcohol or 
 chloroform. If using detachable post crown, remove the porcelain, attach the sprue 
 wire at the thickest point of the wax, viz., at the palatal heel. Also attach another 
 wire (24 or 25 gauge) at a point as near the labial surface as is possible. When 
 investing pass the second wire through a hole made in the side of the bucket for that 
 purpose. After the investment has set, remove the sprue and both wires. The 
 object of the second wire is to provide an escape for the air or gas which would other- 
 wise be confined in the mold. 
 
 It will be found difficult to cast the gold to a thin edge without this provision for 
 the escape of gas. 
 
 When using a fixed post crown, remember that it is impossible to overheat with 
 natural gas and blow-pipe, and the hotter the case the less liable is the porcelain to 
 check. 
 
 After casting, smooth with paper discs and polish. The result will be a perfect 
 adaptation to root and crown. In cases of enlarged root canal the wax and con- 
 sequently the gold can be forced up on the post, thus gi\ing extra strength and a 
 perfect adaptation of the post to the root. 
 
SHRINKAGE OF THE INVESTMENT— INVESTING THE WAX MODEL 
 
 SO AS TO PROCURE THE MINIMUM POSSIBILITY 
 
 OF DISTORTION 
 
 By C. J. Clark, D.D.S., Chicago, 111. 
 
 The instability cf the investment used for the purpose of terming the mold 
 into which the molten metal is forced, has been considered the prime factor in 
 contributing to the cause of many failures in the process of casting gold under 
 pressure. It being charged — 
 
 1st. That the investment being porous, allows the pressure to envelop the 
 m(?ltcn metal in the mold, causing distortion and augmenting the shrinkage cf the 
 metal. 
 
 2nd. That the investment is not of sufficient integrity to withstand the contact 
 of the molten metal when considerable pressure is used to force the molten metal 
 into the mold. 
 
 3rd. That the investment shrinks, thereby causing a distortion cf the mold. 
 
 THE POROSITY OF THE INVESTMENT 
 
 The porosity of the investment can be considered as a detrimental factor only 
 
 in cases where the force used to drive the metal into the mold is an expanding gas 
 
 and in an extensive piece of work, the pressure not being restricted to exert its force 
 
 on the metal in the crucible, but being free to penetrate the investment by virtue cf 
 
 %-/ -TigJ ^» ^ 
 
 its porosity, and to envelop and attack the metal on all surfaces, thereby causing 
 compression from several directions, and must exert a deleterious influence on the 
 finished product. 
 
 Before a cast is made the mold contains air, and when the metal is forced into 
 the meld, it must displace the confined air and expel it into the porous in\estment, 
 where it meets and offers opposition to and impedes the free expulsion cf air from the 
 meld, thereby retarding the ingress of the metal into the mold. 
 
 THE INTEGRITY OF THE INVESTMENT 
 When we consider the extreme fluidit}- of the molten metal, if judgment is 
 exercised, there is no danger from this source; for the molten metal is in such a state 
 as to be incapable of making any impression on the walls, angles and convolutions 
 of the mold as it might if in a more coherent condition. The direct opposite is true, 
 the walls, angles and convolutions of the mold, imprint their e\ery reflection on the 
 surface of the molten metal, and unless an excessive force be used, there is no danger 
 of distorting the mold from the impact of the molten metal. 
 
16 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 THE SHRINKAGE OF THE INVESTMENT 
 
 Let US suppose Fig. 1 to represent a bar of iron 36 in. in length and 12 in. in 
 width, and of equal density throughout the mass. Under a definite degree of heat 
 it will expand to the extent of 3-24 of an inch in each direction from its mean line 
 
 ^^3 
 
 of linear expansion and 1-24 inch in each direction from its mean line of lateral 
 expansion. The dimensions of the bar would then be 36 + 3-24 + 3-24 = 36 6-24 
 + 12 + 1-24 + 1-24 = 12 2-24 or 36 6-24 + 122-24 as represented by Fig. 1. 
 Now let us suppose that the same bar is bent into the form of a ring, the inner cir- 
 cumference of which would measure 36 in. with a consequent diameter of approxi- 
 mately 12 in. (The diameter of a circle being determined by dividing the circum- 
 ference by three and a fraction, the fraction being omitted to simplify.) The 
 dimension of the outer circumference is immaterial. Now if the same definite degree 
 of heat be applied as was to the straight bar, we will discover that while the dimen- 
 sion of the outer circumference has increased, the dimension of the inner circum- 
 
 ^^•5 
 
 ference remains unchanged. F"or the simultaneous increase of the outer and inner 
 dimension of the respective circumferences, without taking into consideration the 
 lateral expansion of the ring, would form a ring the inner circumference of which 
 would measure 36 6-24 with a resultant diameter of 12 2-24 (Fig. 3). But the 
 lateral dimensions of the ring are increased by expansion to the extent of 1-24 inch 
 in each direction from the mean line of lateral expansion (see Fig. 3 and note dotted 
 lines) thereby increasing the lateral dimension of the ring toward the center of the 
 
SHRINKAGE OF THE INVESTMENT 
 
 17 
 
 inner circumference, thus decreasing the dimension of the diameter 1-24 inch at any 
 and every point on the inner circumference of the ring, or 12 2-24 — 2-24 = 12 in., 
 the 2-24 decrease in the dimension of the diameter due to lateral expansion, offsetting 
 the 2-24 inch gained by the 6-24 inch increase of the circumference. Therefore, the 
 diameter of the inner circumference will measure 12 in., being identical to the measure- 
 ment of the diameter before e.xpansion occurred. Thus, when the lateral measure- 
 ment (B. C, Fig. 1) of an iron ring equals the diameter of the inner circumference of 
 the ring (Fig. 1 D. E.) should any expansion or contraction occur, the dimension 
 of the diameter of the inner circumference remains unaltered. Let F"ig. 4 represent 
 a ring, the circumferential dimensions of which arc identical to Fig. 2, but with the 
 inner circumference eccentric to the outer circumference to the extent as shown in 
 diagram 4. The lateral dimensions of the ring being no longer uniform, should an>' 
 expansion occur, it would vary in proportion to the changing lateral dimension. 
 Thus, where the lateral dimension measures 24 in., the expansion would be 2-24 in. 
 in each direction from the mean line of e.xpansion; or an expansion of 2-24 in. toward 
 the center of the inner circumference, which would cause a decrease in its diameter 
 
 j^y^-6 
 
 ^i^-7. 
 
 of 2-24 in. at that point, and where the lateral dimensions measure 12 in. the ex- 
 pansion would cause an increase of 1-24 in. in each direction from the mean line of 
 lateral expansion, with a corresponding decrease of the diameter of the inner circum- 
 ference, at that point. Therefore, the lateral expansion would be of an unequal 
 and varying degree throughout the ring, registering the same varying degrees of 
 inequality upon the inner circumference of the ring. Hence, the inner circum- 
 ference would no longer maintain the lines of a perfect circle, and the ring would be 
 described as having become warped and the inner circumference distorted. 
 
 Now these same laws which govern the expansion of an iron ring, are also 
 applicable to contractions, and also to any substance capable of exercising the 
 property of expansion or contraction. For instance, investment material would be 
 included, it having a tendency to shrink under the application of terrific heat. Suppose 
 we desire to cast a perfect ball; if the wax model was surrounded by an investment 
 of equal consistency, held by a flask in the form of a globe (Fig. 2 could be applied as 
 cross section), and the thickness of the investment equaled the diameter of the wax 
 model, should expansion or shrinkage occur, the dimensions of the mold would remain 
 unchanged. Again, suppose we desire to cast a perfect ball, but the model is placed 
 eccentric to the external surface of the investment (to which Fig. 4 could be applied 
 as a cross section) so that the in\('stmont would be of une(]ual anfl \arying thickness, 
 
18 PRACTICAL MANUAL OF DENTAL CASTING 
 
 then should any expansion or contraction occur, it would be unequal in proportion; 
 as the lateral dimensions are unequal and the effect would be registered on the walls, 
 angles and convolutions of the mold, and the investment would be described as 
 warping, and the mold as being distorted. Now again, let us suppose it is desired to 
 cast a perfect ball, but in an ordinary flask used for dental purposes. Now, if the 
 wax model is attached to the sprue wire and mounted on the crucible former, and the 
 model encapsuled by investment of uniform thickness, equal to diameter of the 
 model, (see Fig. 5) and after this has cr^'stallized, place the flask over it, and com- 
 pletely fill it with investment material (Fig. 6). Then should any shrinkage occur 
 during the process of obliterating the model, or fusing the gold in the crucible, it 
 would be incapable of exerting any deleterious effect on the mold. And for this 
 reason — that the continuity between the first and second stratum of investment is 
 broken and should any shrinkage in the second stratum of investment occur — it 
 being of unequal thickness — the effect of the shrinkage on the mass would be unequal; 
 but the continuity between the first and second stratum being broken, the second 
 stratum would draw away from the first stratum causing no distortion to ic (the 
 first or inside stratum) and should the mass comprising the first stratum subse- 
 quently shrink, this mass being of uniform thickness and equal in measurement to 
 the diameter of the model, should any shrinkage occur the form of the mold would 
 practically be unaltered (Fig. 7). Hence, during the process of investing a model 
 for the purpose of making a matrix or mold for the casting of gold or any metal under 
 pressure, if the model is encapsuled by a stratum of investment of uniform thickness 
 and equal to the thickness of the model, and be allowed to crystallize, and then this 
 surrounded by the flask and enveloped by a second stratum of investment, it is, for 
 all practical purposes, a geometrical impossibility to distort the mold, should shrink- 
 age of the investment occur. The operator can exercise his ingenuity to an unlimited 
 degree, in investing to the best advantage, rnodels taken from compound approximal 
 cavities including occlusal fissure cavities and copings, so that only an infinitesimal 
 degree of distortion can possibly occur, should the investment shrink or even check. 
 
 METHOD OF RESTORING BICUSPID ROOTS TO USEFULNESS 
 
 By Auber Peebles, D.D.S., Wilmington, Ohio 
 
 There are roots of superior bicuspids sacrificed many times, when a little time 
 and careful effort would make good foundations for the support of strong and 
 serviceable crowns. 
 
 In this case decay has extended to such a distance that separation at the bifurca- 
 tion has taken place. These roots, which are so often extracted, are disinfected, filled 
 and so shaped, that small gold caps may be made to fit each one accurately; and in 
 each cap an iridio-platinum pin is soldered as for a Richmond crown. These caps 
 with pins attached are removed in impression and mounted on model of investing 
 material so as to be able to solder over ends, an oval piece of platinum plate about 
 28 or 30 gauge: then you have the foundation for a crown. 
 
 The remainder of crown is made by adjusting a facing of suitable size and color 
 to correspond with the other teeth, and after backing it with 40 gauge 24k. gold, 
 wax up an inner cusp to properly occlude with lower teeth, and invest in casting ring. 
 After casting with 18 or 20k. gold direct to backing, polish and you have a very 
 strong and very serviceable crown instead of a bridge, which would have been neces- 
 sary had roots been extracted. 
 
A THEORETIC CONSIDERATION OF THE EXPANSION AND CON- 
 TRACTION OF GOLD WHEN CAST UNDER PRESSURE 
 By C. J. Clark, D.D.S., Chicago, HI. 
 
 One of the perplexing questions that has confronted the dental profession, and 
 been the subject of controversy and discussion since the process of casting metal 
 under pressure has been practiced, is the question of shrinkage and expansion. 
 Of all the literature I have read pertaining to this intricate subject I have, so far, 
 failed to find anything that gave a correct exposition of this question, or depicted a 
 true scientific portrayal of the metamorphosic phenomena the metal undergoes in 
 its transition from the molten to the solid state. 
 
 I have read ably written papers comparing the shrinkage of gold when cast 
 under pressure, to the shrinkage of steel rails. I have perused columns of figures, 
 carefully compiled, showing the degree of expansion and contraction of gold under 
 normal conditions, but this is immaterial and not applicable; on the contrary, it is 
 flagrantly fallacious when applied to gold cast under pressure, while the molten 
 metal is confined within the unyielding embrace of rigid walls. 
 
 Of all the mechanical achievements that man can boast, there is not one that is 
 not a modification of some mechanical principle utilized in the unfathomed labora- 
 tories of nature. In regard to the art of molding and casting, the same cosmic 
 laws prevail with infallible accuracy, whether the proportions are the seething molten 
 mass of an uncooled planet, or an insignificant globule of gold no larger than a pea. 
 Science teaches that the planets and all the solar system once existed in the form 
 of nebulous or gaseous matter, scattered throughout the boundless oceans of space, 
 whirling and revolving, gradually' cooling and growing denser, throwing olT portions 
 from what we may term parent bodies, and these cast off portions in turn throwing 
 off other portions from their mass, until this sort of process in time evolved our 
 solar system. 
 
 So for countless ages the matter of this earth existed in a molten state, gradually 
 cooling and shrinking until the surface became rigid and the internal molten mass 
 became encapsuled by a crust. As the shrinkage continued, matter was called upon 
 to supply the deficiency, and the crust being solid and rigid and held by the power of 
 cohesion, the power of centrifugal force was greatest at the greatest circumference, 
 and of course the portion of the revolving sphere that offered the least resistance 
 (the poles) succumbed to the demands of the internal shrinkage and were drawn 
 inward; and so we find the earth slightly concave at the poles. 
 
 The cooling of the metal in a mold, while not exactly similar, is strikingh- 
 analogous to the cooling of a planet or the earth on which we live. 
 
 Matter is never at rest; the atoms comprising the molecules revolving around a 
 common center, forming a miniature solar system, are in a constant state of agitation, 
 moving rapidly around in their medium of ether, and confined in their movement 
 to the limited space between their fellows. 
 
 Now the outer surface of a mass of matter is the first to be susceptible to any 
 thermal change, the effect being transmitted toward I he center, and if this thermal 
 
20 PRACTICAL MANUAL OF DENTAL CASTING 
 
 change be of a sufficiently high degree to change the state of the mass from the soHd 
 to the liquid, or gaseous, or vice versa, the surface is the first to exhibit these mani- 
 festations. (Fig. 1.) 
 
 Fig.l 
 
 Let us suppose Fig. 1 to represent a cross section of gold plate, magnified to 
 such an extent that the molecules are visible, and represented by the small circles 
 or spheres. Now, should this plate be subjected to a heat of a sufficient degree, the 
 atoms of the molecules revolve more rapidly than before, become more divergent 
 in their tendency, describing a larger circumference about their common center, the 
 molecules increase in the same proportionate volume, and their mutual power of 
 cohesion diminishes, and this allows the molecules to separate more widely, and 
 permits of a greater latitude in which to exercise their mobility. As the atoms are 
 whirling about their common center the molecules are revolving, and revolving also 
 about each other, generating centrifugal force to such an extent as to overcome the 
 force of gravity, and with a tendency towards projection in every direction; held in 
 restraint only by the still active but greatly diminished power of cohesion. This 
 causes some molecules to be lifted above their fellows and as heat increases the mass 
 begins to assume a globular form (Fig. 2), and presents a panorama of rhythmic 
 harmonious action. 
 
 Now if the heat be withdrawn the revolutions of the atoms about their common 
 centers decrease, and as their momentum gradually diminishes the atoms come into 
 closer proximity, the molecules decrease in volume, the power of cohesion increases, 
 the mutual attraction of the molecules becomes more intense, exhibiting more in- 
 fluence than the force of gravitation, and the congealing mass of metal retains more 
 or less of the globular form; the molecules being caught in the act of falling much 
 the same as water is caught and held in the formation of an icicle, see Fig. 3. 
 
 The duration of time in which the metal is transformed from a molten to a solid 
 state is exceedingly short, and the fact that the metal retains enough heat to main- 
 tain a red color for a time, furnishes no scientific proof that the metal in the mold 
 will shrink, for the metal that remains in the crucible and the metal in the mold 
 encounter conditions in hardening that are diametrically opposed. The metal in 
 the crucible is confined by no walls, and the pressure on it being from without inward 
 has no suchefifect as on that confined in a mold, for the reason that the hydraulic 
 I)ressure that the confined gold is subjected to forces the metal from the center out- 
 wardly as long as it remains molten, and thus it is pressed against the cooler walls 
 where the crust as described is formed, and which will register a density of 19.45, 
 
EXPANSION AND CONTRACTION OF GOLD 21 
 
 against 19.16 of that remaining in the crucible, and there is no inherent force or 
 physical property in the metal itself after being cast under pressure capable of aug- 
 menting its density to any further degree, so it is physically impossible for it to 
 
 Fis-, 3 
 
 shrink. Therefore, if in the process of making an inlay or a more extended piece by 
 casting under pressure any distortion occurs, or it is not a fac-simile of the wax 
 model, the discrepancy must be ascribed to some other factor or cause than the 
 shrinking of the gold. 
 
 References consulted on Expansion and Contraction of Metals: 
 
 (Chicago Public Library.) 
 Clark, D. K. A Manual of Rules, Tables and Data for Mechanical Engineers. 1878. *K 598. 
 DuBois, A. J. Elementary Principles of Mechanics. Vol.2. 1894. K 4982,2. 
 Dana, E. S. (ed.) American Journal of Science. Vol. 161. 1901. Ser. 
 Howe, H. M. Metallurgical Laboratory Notes. 1902. K 12780. 
 Hutton, W. S. Practical Engineer's Hand-Book. 1896. K 5405. 
 Lineham. VV. J. Text-Book of Mechanical Engineering. 1894. K 4958. 
 Poynting, J. H. and Thomson, J. J. Text-Book of Physics. 1904. K 15930,.3. 
 Rankine, W. J. M. Manual of Civil Engineering. 1891. K661. 
 Useful Rules and Tables. 1873. K 665. 
 
 Thurston, R. H. Brasses, Bronzes and Other Alloys. 1900. K 5502,3. 
 Watson, W. Text-Book of Physics. 1905. K 15933. 
 
 If this globule of gold were measured for its specific gravity' it would be found 
 that it developed, by the mutual attraction of its molecules (cohesion) a density that 
 registers a relative specific gravity of 19.16. Thus, if gold, heated so as to assume 
 the liquid state, be allowed to congeal uninfluenced by any interfering conditions, 
 the only factors entering into the phenomena being mass, cohesion, heat, molecular 
 mobility, volume and gravitation, it is a physical impossibility for the metal to 
 develop, by virtue of its cohesive force, a density that registers a relative specific 
 gravity above 19.16. In the casting of metal under pressure, additional factors 
 enter, and must be taken into consideration; they are hydraulic pressure and welding, 
 the latter being induced by the force of hydraulic pressure. 
 
 If a mold has been prepared in the usual procedure for a cast under pressure, 
 and is in a condition for the reception of the molten metal, a button of gold fused in 
 the crucible manifests the same physical phenomena previously described and 
 represented by Fig. 2. The atoms will revolve around their common center more 
 rapidly than at a lower temperature, and the molecules will revolve around each 
 other in like manner and the metal is gradually transformed from the solid to the 
 molten or liquid state. If force now be suddenly applied to the liquid mass in the 
 crucible a portion of it will be forced by displacement into the mold, and if the 
 pressure be maintained for a time it will be transmitted from molecule to molecule 
 simultaneously in every conceivable direction, the hydraulic force pressing the mole- 
 cules to all surfaces and angles of the mold. As the molecules at the surface of the 
 mass come in sudden contact with the walls of the mold, their movements are 
 abruptly checked, the atoms of the molecules are forced to closer proximity, the 
 molecules decrease in volume and have less latitude in which to exercise their 
 
22 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 mobility, which instantly induces congealation; and as they are held firmly against 
 the walls of the mold, gaps and crevices occur, which are, however, filled by the 
 pressure behind, and with inconceivable rapidity, with new recruits, frenzied and 
 
 fi&4 
 
 heat-maddened, where they meet the same fate as their fellows, crushed and jammed 
 against each other and the walls of the mold until in congealing a rigid wall or 
 capsule lines every surface and angle of the mold. (See Fig. 4.) 
 
 This goes on in the same way until the surface crust thickens to the center, all 
 following the same regular order of things, but with no loss of appreciable time, in a 
 small mass of gold as might be inferred from the deliberate description. This metal 
 will be found to be of higher specific gravity than when it is allowed to cool under 
 ordinary conditions. A pressure of 12 pounds induced by expanding gas will bring 
 about a density or specific gravity of 19.45. 
 
 TELESCOPIC CROWN FOR BRIDGE WORK 
 
 By E. L. Kanaga, D.D.S., Philadelphia, Pa. 
 
 No. 1. A piece of metal for the band is cut from 30-gauge coin gold, the oc- 
 clusal end being 1-32 of an inch smaller than the gingival. 
 No. 2. Showing the band joined sweated. 
 No. 3. The floor sweated to the band. 
 
 No. 4. The core is formed by holding the inner cap in a paper form and 
 pouring fusible metal into it. 
 
 No. 5. The outer cap is made l)y dri\'ing the inner cap, now mounted on the 
 core, into it. 
 
 No. 6. Shows method of obtaining contour. 
 
THE EXTENT TO WHICH THE CASTING PROCESS MAY BE 
 
 ADVANTAGEOUSLY APPLIED TO CROWN AND 
 
 BRIDGEWORK 
 
 By Hart J. Goslee, B.S., D.D.S.. Chicago 
 
 The full extent to which the application of the casting process may have 
 revolutionized the practice of dentistry is, of course, difificult to determine, but 
 it is safe, I think, to say that its influence has been, and is now being, felt to a 
 greater or less extent by even the most obscure dentists in the most remote districts. 
 
 Whether all who are now doing casting in some form or other will care to 
 acknowledge it, or whether they will concede its revolutionary influence, and the 
 marked advancement made possible by its application, or not, may be a question; 
 but that at least a very large percentage of dentists are doing casting, and that 
 they are doing better work, and doing it with infinitely greater comfort to their 
 patients and with the expenditure of less nervous energy on their own part than 
 they formerly did, there can be no question. 
 
 That some are much more enthusiastic over its possibilities than others, and 
 that some are getting much better results than others is also unquestionable, 
 and it is as interesting as it is true. 
 
 However, this is but a natural sequence and should be expected in any field 
 of effort in which former accepted practices and methods of long standing become 
 so completely revolutionized and supplanted, if you please, in so short a period of 
 time; where the pedestals upon which the cherished reputations of so many 
 prominent practitioners were made to crumble and totter, almost in a day; where 
 old and young must begin anew and alike, and where the application of this 
 newer practice and its practicability must necessarily be tinctured with a saturated 
 solution of personal equation. 
 
 From the beginning, however, it has been interesting to note that those who 
 were early to grasp the possibilities of casting and, hence, who have been and are 
 still doing the most of it, are the most enthusiastic over it, and, therefore, does it 
 not naturally follow, by the same rule of thumbs, that those who were first to 
 grasp and accept its wonderful possibilities, who have been and are still doing 
 the most of it, and who are most enthusiastic over it, are also the ones who are 
 obtaining the best results? 
 
 While it may be true that the proportion of those who ever attain to the verj' 
 highest achievements in any mechanical pursuit is not a large one, still I am of the 
 very firm belief that the casting process has afforded an opportunity for raising 
 the standard, and increasing the percentage of uniformly good results; and, in 
 the light of our present achievements, that this standard will become higher and 
 higher in proportion as we recognize our own personal limitations, and realize the 
 full scope of its possibilities. 
 
 Those, who by a process of self-analysis, maj' thus recognize their own limi- 
 tations will not expect a mechanical process, or a machine of any make or kind, 
 to adjust and adapt itself to the varying and intricate demands of an e.xacting 
 
24, PRACTICAL MANUAL OF DENTAL CASTING 
 
 line of work, unless the process is followed, or the machine operated, with an 
 average degree of human intelligence, but those who fail to recognize this are 
 surely destined to meet with failure. 
 
 Thus it is more than probable that many may have failed in attaining to 
 the heights of even average success simply because they expected too much of the 
 process involved, and exacted too little of themselves, but those in this class never 
 become enthusiasts, and those who never become enthusiasts rarely become 
 experts in any line. 
 
 Enthusiasm, expertness and all that goes with, to make for, and insure, 
 success in the application of any mechanical process can, after all, come only 
 from the "man behind the gun," and hence the operator who aspires to such 
 must be willing to acknowledge this fact and contribute his share; and in this 
 instance his share is in the form of ammunition, and the ammunition now needed 
 most of all is correct and accurate technique. 
 
 While the factor of personal equation will necessarily demand a more or less 
 different technique for each and every operator, yet the most scrupulous attention 
 to details, and the utmost of accuracy is necessary in each instance, and as such a 
 technique is to be acquired only at the expense of time, thought and energy, it is 
 scarcely purchasable, nor may it result from delegating important parts of the 
 work to laboratories, or to inexperienced or unskilled assistants, as is a common 
 but bad practice. 
 
 When the average operator realizes these essentials to success, then the 
 average operator may reasonably hope to rise above the average and achieve 
 success in the application of the casting process, and as he appreciates them will 
 he also find the field of usefulness broaden and the possibilities become more and 
 more unlimited. 
 
 If there were no field to which the casting process may be applied other than 
 the one which embraces the filling of teeth, however, let me ask you what a long- 
 felt want would it still afford; what a broad field of usefulness would it occupy; 
 what a priceless advancement would it mark in the preservation and restoration 
 of the teeth, since it is now generally conceded that the inlay affords a better, 
 quicker, less painful and probably, on the average, more permanent character of 
 operation? 
 
 Granting all of this to be true, however, the limitations of this process have 
 by no means yet been reached. Indeed, it seems that they are still only in their 
 infancy, and that the field of usefulness as applied to all other phases of practical 
 dentistry is as broad and far-reaching as is the degree and character of success 
 already insured in the filling of teeth. 
 
 While this is undoubtedly true, to a greater or less extent, as applied to the 
 whole field of dental prosthesis, it is particularly true as applied especially to the 
 subject which it is my purpose to discuss at this time — that of crown and bridge 
 work. 
 
 But a few — a very few — years ago this line of our work, which many of us 
 are now pleased to designate and dignify as a "specialty," was but an indetermin- 
 able collection or mass of empirical details. Almost every dentist had his own 
 ideas, and his own methods, and each differed from the other to such an extent 
 as to confuse the teacher, and bewilder the beginner, in every respect and direction 
 except one — the display of gold. 
 
 For many years patients wearing crown or bridge work, however limited or 
 
CASTING PROCESS APPLIED TO CROWN AND BRIDGEWORK 25 
 
 extensive in character, were involuntary advertising mediums for dental jewelers; 
 were forced to display shocking evidences of a handicraft which, while in some 
 instances useful, perhaps, were usually far short of art, and always more or less 
 repulsive. 
 
 These evidences, I am sorry to say, may still be obser\'ed, but fortunately 
 not to the same extent. As a profession, we are beginning to strive for higher 
 ideals in the art side of our work, and in this respect we are aided materially by 
 the demands of an ever-increasing degree of culture on the part of our patients. 
 
 Since porcelain has always been and is still the one substance which most 
 closely simulates nature, and therefore best meets the requirements, this fact, 
 together with these combined ambitions on the one part, and demands on the 
 other, must lead one to conclude that more porcelain and less gold must be used 
 in an effort to satisfy each. 
 
 While this was recognized many years ago, still the inherent element of struc- 
 tural weakness so characteristic of porcelain, and so often learned from sad 
 experiences, together with the knowledge that cosmetics was but one requirement, 
 and that in the construction of all forms of crowns and bridges the actual mechan- 
 ical requirements of strength and accuracy of adaptation must necessarily receive 
 first consideration, it is no great wonder that cosmetics was accordingly sacrificed. 
 
 If it were not, and if it is not, possible to obtain both of these requirements 
 at one and the same time, then cosmetics should be placed second to, or sacrificed 
 for the purely mechanical, but the possibilities of casting offer opportunity for 
 obtaining all of the combined requirements to the very highest degree, and hence 
 its application may be made to practically^ revolutionize all of our former methods. 
 
 This is possible because the casting process, skilfully utilized, insures, first, 
 accuracy of adaptation, and, second, a maximum of strength with a minimum of 
 gold: and in the proportion as the amount of gold necessary to insure strength 
 may be decreased, the amount of porcelain may be increased. Thus, if our work 
 be properly constructed, less gold and more porcelain may be safely and success- 
 fully used, and the suggestions which I have to offer you along these lines are based 
 entirely upon the theme of more porcelain and less gold with equal and adequate 
 strength. 
 
 Such manifestly desirable advantages are now to be obtained by means of a 
 skilful application of the casting process, combined with a more general use of 
 all-porcelain teeth instead of the ordinary thin facings. 
 
 You will probably agree with me that this type of tooth is preferable for single 
 artificial crowns, because it affords better form, better color and greater strength 
 than it is possible to obtain from the use of facings. Also that an all-porcelain 
 tooth is better for bridge work because the presence of an occlusal surface of 
 porcelain instead of gold, on any or all of the posterior teeth, is advantageous not 
 only for cosmetic and hygienic reasons but for actual masticatory purposes as well. 
 
 These advantages are so evident that the more esthetic operator has been 
 forced to look and hope for some form of tooth, and some method of application 
 which would eliminate the inherent weakness of thin facings, and the objectionable 
 features incident to their use. 
 
 To overcome the shortcomings of the so-called "Richmond" crown, and of 
 the ordinary bicuspid and molar dummy with porcelain facing and gold cusps, 
 the advantages of some form of interchangeable or replaceable all-porcelain tooth, 
 more closely simulating the form and color of the natural teeth, were early recog- 
 
26 PRACTICAL MANUAL OF DENTAL CASTING 
 
 nized. As a result of this recognition, many types have been introduced, but until 
 very recently most of them have been of the thin facing variety, and applicable 
 to the anterior teeth only. 
 
 While the all-porcelain teeth, such as the Davis, Logan and Justi crowns, 
 have always been recognized as being the nearest approach to an ideal substitute 
 for the natural teeth, yet they were not originally designed to meet the present 
 requirements of crown and bridge work, and hence their use has been confined 
 to that class of cases where more or less temporary results were all that was ex- 
 pected or demanded. 
 
 If the esthetic and hygienic advantages possessed by this type of tooth, 
 however, could be combined with those of exact adaptation, and uniform and 
 adequate strength, and if to these might be added the further advantages of being 
 cemented to the structure instead of soldered, and of being replaceable and more 
 or less interchangeable, it is evident that our efforts would be a nearer approach 
 to the ideal. 
 
 In my opinion, which has been often expressed, the attachment of porcelain 
 teeth or even facings to the metal structure by means of soldering, or of direct 
 casting, is wrong. It is a wrong principle because the porcelain is subjected to a 
 degree of heat which must endanger its structural integrity and influence the 
 preservation of its color; because the tooth or facing is thus attached in a stiff and 
 rigid manner, and, being friable, is more likely to fracture under the stress of masti- 
 cation; and because, in the event of accident, no favorable opportunity for repair 
 or replacement is usually afforded. 
 
 I think you will also agree with me, therefore, that the elimination of these 
 objectionable features must necessarily constitute an improvement, and that such 
 an improvement is to be obtained by the use of replaceable teeth attached to the 
 supporting metal structure only by means of cementation. 
 
 An experience of many j^ears has proven that this means of attachment is 
 reliable in proportion as the adaptation of the metal to the porcelain may be close 
 and accurate, or, in other words, in proportion as the porcelain may be "boxed 
 up," protected and supported. It is stronger when so attached because it is not 
 subjected to any degree of heat, and is not held so rigidly, due to the cushion-like 
 effect afforded by cement; and because, not being held so rigidly, it is less likely 
 to become fractured. Furthermore, the color is never changed; those dark blue 
 marginal outlines due to the penetration of saliva between backing and facing are 
 absent, and opportunity and facility for replacement in the event of accident 
 always presents. 
 
 As I have previously stated, these possibilities and advantages are to be 
 adequately obtained only in some form or type of tooth which presents as much 
 porcelain as possible, which porcelain is not weakened by the presence of metal 
 pins nor by the provisions for retention, and which, therefore, possesses a maximum 
 of strength; which is of natural form, more or less universally applicable, and which 
 will need but a minimum of grinding for effecting the desired and required adap- 
 tation. 
 
 This latter feature, as applied to the retentive surface, is essential, because 
 in proportion as a given form of porcelain tooth will require but little or no grind- 
 ing upon this surface in effecting its adaptation to the requirements of the individual 
 case, may it be expected to be replaceable or interchangeable. 
 
 These combined advantages, I believe, are to be obtained in a form of tooth 
 
CASTING PROCESS APPLIED TO CROWN AND BRIDGEWORK 27 
 
 suggested by your essayist, and now known as the "Goslee Interchangeable 
 Crown and Bridge Tooth," (Fig. 1) to which I am pleased to call your attention. 
 
 It will be observed that these teeth as now made are of natural form; that they 
 possess the splendid strength and color characteristic of the Consolidated tooth 
 bodies; that they are adapted to single crown work where any form of metal base 
 is used, as well as to intermediate teeth, or "dummies" for bridge work; that they 
 afford a minimum display of gold and require but a minimum amount of grinding, 
 and that with a sufficiently large variety of molds they should be almost uni- 
 versally applicable; also, that they are strongest where the greatest strength is re- 
 quired; and that they offer ample opportunity for secure retention to the supporting 
 base or structure. 
 
 A further advantage made possible by the use of replaceable or interchangeable 
 teeth, which applies particularly to especially difficult cases, is to be obtained 
 by making duplicates, and while it is true that any form of interchangeable tooth 
 
 
 Figure 1 
 
 is far less likely to become broken from the stress of mastication, yet the making 
 of duplicates coincidentally with the initial construction requires but little time, is 
 always a source of inestimable protection to the particular patient, and affords 
 unlimited relief and satisfaction to the dentist. It is, therefore, a safeguard which 
 might be observed often and profitably by everyone whose necessarily small fees 
 do not render it prohibitive. 
 
 In all instances, however, whether duplicates are made or not, the color 
 number and mold number of each tooth used in every case should be recorded on 
 the card or ledger sheet, and thus made a permanent part of the record. Because 
 of these advantages and for these various reasons I firmly believe that only some 
 form of interchangeable tooth should ever he used in single crowns, or "fixed" 
 bridge work, of any type, if the best results and highest possibilities are to be 
 attained in our efforts. 
 
 In addition to such desirable improvements as may be achieved by the use of 
 teeth of this character, the introduction and application of the casting process has 
 placed this field of our effort upon a more systematic and practical basis, as an 
 evidence of which permit me to call your attention to the methods which I am now 
 generally employing, almost to the complete exclusion of all other and former 
 procedures. 
 
 SINGLE CROWNS 
 
 For the ten or twelve anterior teeth, or all teeth within the range of vision, 
 where porcelain is demanded, the all-porcelain replaceable or interchangeable 
 
28 PRACTICAL MANUAL OF DENTAL CAST INC 
 
 crown, with cast base, and with or without a band, as the requirements may 
 indicate, is used in a very large percentage of cases. It is undoubtedly the 
 strongest, most artistic, and most universally applicable type of substitute for 
 the natural tooth, and in all respects is second only to a skilfully adapted "jacket " 
 crown. Indeed, for the average dentist it is better, more quickly and easily 
 made, and, moreover, it possesses an advantage over the latter in that immediate 
 replacement, in the event of a mishap, is possible. 
 
 PORCELAIN CROWNS WITH CAST BASE 
 
 In the construction of this type of crown much difficulty has heretofore been 
 encountered in molding the wax to a close adaptation to both the root-end, par- 
 ticularly at the periphery, and the base of the crown, and in holding the dowel or 
 dowels in the proper position to insure correct alignment. 
 
 These essential features have usually been so uncertain, and in some instances 
 so difficult and so unsatisfactory, as to cause me to work out and suggest a technique 
 which eliminates such uncertainty, which insures accuracy, which is applicable 
 alike to all cases, whether a band is required or not, which relieves the patient of any 
 discomfiture whatever, and which has proven the most satisfactory method of 
 crown construction I have ever followed. 
 
 In the various methods now generally used and advocated, good, accurate, 
 reliable results are difficult to obtain, because the very plasticity of wax of any 
 kind makes it possess a tendency to spread when subjected to the pressure neces- 
 sary to mold it to a close adaptation. This tendency is best and most easily over- 
 come by first adapting 38 gauge pure gold to the root-end, which may be done 
 either by swaging or burnishing, and then adjusting the dowel, tacking it to the 
 base with solder, and subsequently molding the wax to both base and tooth and 
 casting directly to this disc of pure gold. If carefully done, the surface thus 
 obtained will always be a closer fit to the root-end than can be obtained from the 
 molding of wax alone with any investment material now procurable, and will 
 require no finishing whatever after casting. 
 
 Such a procedure also reduces to a minimum the possibility of any change 
 of form which may result from the warpage or shrinkage of the gold or alloy used 
 in casting, but to obtain the best results necessarily involves the impression and 
 die method, as illustrated in Fig. 2, and explained in detail in the Dental Cosmos, 
 August, 1911. 
 
 The entire process requires but little time, is simple, insures a more or less 
 perfectly adapted base, and one which is obtained without the slightest discom- 
 fiture to the patient, which is not possible when burnishing directly to the root-end 
 is attempted. For single crowns a slight lingual lip or band is usually all that will 
 be required. This strengthens the attachment between crown and root, and 
 precludes the possibility of subsequent fracture of the root — for which purposes a 
 band is usually used, but in all cases where the crown is to be used as a bridge 
 abutment a full band should remain. 
 
 The construction of a crown by this method usually involves but three short 
 sittings, and the best results are to be obtained by doing all the work directly 
 in the mouth. At the first sitting the root is prepared, the root impression taken 
 the mold number and color selected, and a temporary crown mounted. This 
 latter feature is desirable as a means of packing the soft tissues away to afford and 
 insure a free exposure of the root-end at the next sitting, as well as to relieve the 
 
CASTING PROCESS APPLIED TO CROWN AND BRIDGEUORK 29 
 
 patient of the temporary embarrassment. The amalgam die having been made 
 and the pure gold disc swaged and tooth selected, in the meantime, at the second 
 sitting the cap is fitted to the root, the dowel and tooth adjusted to the require- 
 
 Figure 2 
 
 ments, the dowel then soldered to the cap, and the relation between the tooth and 
 cap secured with casting wax. The crown is then cast, the tooth cemented to 
 place and finished, and the final mounting is made at the third sitting. 
 
30 PRACTICAL MANUAL OF DENTAL CASTING 
 
 GOLD CROWNS 
 
 For second and third molars — and even first molars, when the presence of 
 gold is not objectionable — the cast gold crown affords results far in advance of 
 anything heretofore obtained. In the construction of gold crowns by the casting 
 process, however, the fit or peripheral adaptation is, because of the spreading 
 tendency of the wax, always best obtained by previously fitting some form of 
 band to the root and then casting directly to it. 
 
 Technique — Whenever it is desirable to exaggerate the contour, a narrow 
 band of platinum or 22 karat gold, of about 30 or 32 gauge, should first be made to 
 fit snugly around the entire periphery and then trimmed to evenly approximate 
 the end of the root, after which all of the contouring may be done in wax, which 
 can be best done, perhaps, on a model. 
 
 When an exaggerated contour is not required, however, and one seldom is, 
 the band may be made of 28 gauge, 22 karat gold, and fitted and contoured in the 
 usual manner. When in position en the root, casting wax is then molded to the 
 end of the root inside of the band, and this procedure followed by an imprint in 
 the wax of the opposing ceeth in all the movements of mastication. 
 
 After the band has been removed, its interior should be filled at once with 
 casting investment material and the occlusal surface properly carved, after which 
 it may be invested and cast, using for the casting the same grade of gold of which 
 
 Figure 3 
 
 the band was made (Fig. 3). If the band is thoroughly clean before investing, 
 and the gold to be cast is of good quality and highly fused before casting, a good 
 physical union will usually result, but if it does not, a small bit of 22 karat solder 
 will insure the same. 
 
 These two general types of crowns will meet the requirements of single crown 
 work in a very large majority of cases, and the results by either method are far 
 more accurate than by any of our former methods. 
 
 FIXED BRIDGE WORK 
 
 In fixed bridge work, which constitutes an assemblage of attachments and 
 intermediate dummies, our work may also be simplified, because three general 
 types of attachments and three general types of dummies will be found to meet 
 the requirements in an exceedingly large percentage of cases. 
 
 Attachments — The methods of obtaining attachment to the supporting teeth 
 or roots embrace the porcelain replaceable crown with dowel and cast base, the 
 construction of which has just been referred to, as applied to the roots of anterior 
 teeth, or when it is impossible or inadvisable to preserve the natural crown; the 
 inlay, when the attachment is to be made to the crown of a natural tooth, which is 
 good practice when the remaining natural crown is sufifiriently strong, and the gold 
 crown for the molar teeth when the use of an inlay is for any reason not indicated, 
 
CA STING PROCESS A P PLIED TO CRO IVN A ND BRIDGE WORK ;j 1 
 
 As previously emphasized, wherever a dowel crown is to serve as an attach- 
 ment for bridge work, a narrow band should always be used. In my opinion, this 
 is absolutely essential, because of the additional strain to which the root is to be 
 subjected, and as a means of insuring permanency and precluding fracture. 
 
 When an inlay is to serve as an attachment the cavity preparation is, of 
 course, exceedingly important,, and some form of post or posts should always be 
 used to insure stability and as a provision against the inlay becoming loosened 
 by the strain and possible torsion to which it is to be subjected. 
 
 The general applicability of the inlay as an attachment for bridge work has 
 been a subject of considerable discussion ever since casting became an accepted 
 practice. That it will serve the purpose as well as, and in some respects even better 
 than, a full crown there can be no doubt, providing its adaptation and stability 
 are insured. 
 
 The former depends first, upon adequate and proper cavity preparation, 
 and then careful technique in making the inlay; and the latter depends upon the 
 use of a proper alloy in casting, and upon pins or posts of some form, for the 
 reasons mentioned. 
 
 Figure 4 
 
 Wherever the walls of the supporting tooth are sufficiently strong to insure 
 permanency; whenever a suitable cavity may be properly prepared, the inlay, 
 well-seated and securely anchored, and made of a hard alloy, such as five per cent, 
 platinum in pure gold, coin gold, or 22-karat gold, I am of the impression that such 
 an attachment is often better than a full crown because of the absence of any 
 possibility of gingival irritation, such as is so often present where the latteris used. 
 
 The cavity preparation for such inlays does not differ essentially from that 
 for a simple filling, excepting that its buccal, lingual and cervical margins must be 
 so extended as to carry the margin between tooth and filling beyond any actual 
 contact of the artificial tooth to be supported by it, in order that each and all of 
 these margins may be e.xposed, for hj'gienic reasons. (See Fig. 6) 
 
 "Dummies" — As dummies for fixed bridge work, three general types will 
 answer the requirements in all cases. 
 
 The all-porcelain replaceable crown and bridge tooth with cast backing is 
 adapted to all positions in the arch where the conditions of absorption and occlu- 
 sion will permit their use, and is undoubtedly the ideal form of artificial substitute. 
 Backings for these teeth should usually be cast separately, though they may be 
 made in sections involving the number of dummies between the attachments, 
 which should never exceed three, or possibly four. Better form, cleaned inter- 
 
32 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 proximal spaces, and less display' of gold, however, are obtained by making each 
 backing separately. 
 
 As a means of preserving the proper relation of the short sustaining post which 
 holds the tooth to the backing, and of insuring a smoother surface adaptation of 
 the backing to the porcelain than the ordinary casting investment materials 
 afford, in using this type of "dummy" a thin backing of about 38 gauge, pure gold 
 should be previously swaged to the tooth, as indicated in Fig. 4, and the post 
 soldered to it. It is then always necessary to allow as much surplus end of post 
 as possible to extend beyond, in order to insure strength in the final attachment 
 of this essential part to the completed backing. 
 
 Figure 5 
 
 Casting wax may then be molded to the required form, and the casting made 
 directly upon and against the thin gold backing, by which method any distortion 
 or possible misfit due to shrinkage or warpage is overcome, and the most finished, 
 accurate, and reliable results are insured. 
 
 In the use of this type of tooth in all cases in the upper arch where complete 
 absorption has already taken place, the most sanitary form of structure is usually 
 to be obtained by molding the wax so as to restore or approximately follow the 
 lingual form of the tooth, but tapering down to a narrow saddle at the point of 
 contact with the soft tissue. As a rule, and contrary to the opinions of some, 
 however, wherever the adaptation is good, such a type of construction will be found 
 to be far more sanitary than the usual recesses, shelves, and pockets, so common 
 in the ordinary methods. 
 
 In the formation of this type of saddle, the desired results may be best ob- 
 tained by first burnishing the same thickness of pure gold to the model, between 
 the finished abutments in position thereon, and then trimming it to conform to 
 
CA .STING PROCESS A P PLIED TO CRO WN A NO BRIDGE WORK IV.i 
 
 the size of the necks of the teeth to be supported by it. The general form of the 
 structure may then be made by filling in between this saddle and the backings 
 with wax, after which the piece may be invested and cast. Or in instances where 
 this space is exceedingly small it may be filled with solder. 
 
 In this more or less typical fixture (Fig. 5), it will be observed that practically 
 no gold is displayed anterior to the second molar, and yet that a maximum of 
 strength presentfa throughout. 
 
 In cases where complete absorption has not occurred, a saddle is, of course, 
 contraindicated, but in these cases the neck of the porcelain tooth should accu- 
 rately fit and should bear firmly upon the soft tissue, and the lingual surface of the 
 backing should then be so formed as to be as nearly convex or self-cleansing as 
 possible. 
 
 For those cases in the anterior region where abnormalities of occlusion or 
 elongation of the opposing natural teeth demand a thin facing, the ordinary type 
 of long pin facing may be used. In its use, however, the best results are to be 
 obtained by previously backing it up with thin pure gold, adding wax to this to 
 the desired form, removing the facing and casting. The pins may then be threaded 
 and, when the backings have been assembled with solder, the facings may be 
 cemented to position, thus obtaining all of the previously mentioned advantages 
 of cementation, combined with better form and more uniform strength. 
 
 In addition to these, for those cases particularly in the lower arch, and in 
 exceedingly "close-bites," where cosmetics is not a factor, or where the extent of 
 absorption or the elongation of opposing teeth precludes the use of porcelain in 
 any form, the all-gold, cast dummy may be used. Such dummies may be made to 
 conform to the requirements of occlusion, adaptation to gum — if such is required 
 • — and contact with the attachments, in wax, and then invested and cast in one 
 piece. This type of "dummy" is useful in supplying the lower second bicuspids 
 and first and second molars and may include only the occlusal surface, thus 
 forming the so-called "self-cleansing" type of bridge, or the entire tooth with or 
 without a saddle, as the requirements may be. The former tj-pe of construction 
 is indicated only where there is an excessive degree of absorption, which will 
 permit of sufficient space between the gum and occlusal surface to insure self- 
 cleansing properties, and wherever this space is not great enough to be easily kept 
 clean, direct contact with the gum will afford a more hygienic result. In other 
 words, there should be plenty of space, or none at all. A typical case of this kind 
 showing the use of all-porcelain dummies in connection with inlays is illustrated 
 in another model. 
 
 With these, the problem of attachments and of intermediate dummies for 
 almost universal application is simplified and systematized. 
 
 The remaining feature incident to the construction of all forms of fixed bridge 
 work involves only the proper assemblage of the various parts. While some are 
 casting all attachments and backings with an alloy of five per cent, of platinum in 
 pure gold, and subsequently assembling them with pure gold, thus using no solder 
 whatever, still a good grade of 22-karat gold or coin gold may be used with equally 
 good results. When either of the latter is used, the final assemblage may be 
 effected with 22-karat solder, and providing there is absolute contact between all 
 of the parts to be united, the procedure is thus somewhat facilitated, and the 
 results are uniformly good. 
 
34 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 REMOVABLE BRIDGE WORK 
 
 The same general' ideas are also applicable to the construction of removable 
 fixtures. 
 
 For this class of work, also, three general types of anchorage to the supporting 
 teeth or roots will be found to adequately meet the requirements of the average 
 case. These embrace clasps, the telescoping tube and split post, and the various 
 forms of manufactured attachments. 
 
 Figure 6-A 
 
 Wide clasps encompassing three angles of the tooth, provided with an occlusal 
 rest, not cast, but made of heavy rolled clasp-metal alloy, probably afford the very 
 best means of obtaining anchorage to the natural or artificial crowns of bicuspids 
 and molars. 
 
 That clasps should not be cast is especially emphasized, because the molecular 
 rearrangement resulting from casting most of our present alloys destroys to a 
 greater or less extent the very qualities of strength and resilience demanded of 
 them, and which undoubtedly obtain best in a rolled or drawn metal or alloy. 
 
CASTING PROCESS A P PLIED TO CRO WN A ND BRIDGE WORK 35 
 
 I'imjre ()-B 
 
36 PRACTICAL MANUAL OF DENTAL CASTING 
 
 In all forms of removable bridge work or partial dentures, where clasps are 
 used, however, some form of occlusal rest is necessary as a means of providing 
 against subsequent settlement of the case. If this precaution is not observed, 
 complete loss, of occlusion and usefulness will soon follow. 
 
 The telescoping tube and split-post attachment Is also useful when confined 
 to the roots of the six anterior teeth. 
 
 The Roach, Morgan, Gilmore and other types of manufactured attachments 
 will also be found valuable when used in connection with either porcelain or gold 
 crowns or inlays on the cuspids and bicuspids. 
 
 When the type or types of attachment thought to be best indicated have been 
 selected, adapted, and completed, the casting process then offers splendid oppor- 
 tunity and great possibilities for the subsequent formation of the body of the 
 fixture, and in this connection I believe that the successful casting of large pieces 
 is only a question of the development of proper technique. 
 
 In the construction of cast bases, if a good model of a high grade investment 
 material is obtained, and if the w^ax base is carefully formed, made sufficiently 
 thin and properly stiffened, the process offers the same assurance of accuracy of 
 adaptation and of strength as previously indicated, and the possibilities are equally 
 unlimited. For all forms and sizes of saddles, or bases, coin gold seems to be 
 especially adapted to cast work, and to afford all of the integral strength ordinarily 
 demanded. 
 
 In the presentation of much of this technique, quotations from former papers 
 have been necessary, to a greater or less extent, but the fact that repetition is made 
 to serve in preference to changes and alterations only proves that I am still 
 courageous in my previous convictions. 
 
 As a final suggestion, permit me to again impress upon you the advantages 
 of simplifying and systematizing your methods, and of casting; the necessity for 
 careful technique and the unlimited possibilities resulting therefrom. 
 
CAVITY PREPARATION FOR CAST GOLD INLAYS 
 
 By Thomas P. Hinman, D.D.S., Atlanta, Ga. 
 
 In reading the literature on the subject of cavit}' preparation for cast gold inlays, 
 I find that very little attention seems to have been paid to this most important 
 subject. Operators who had been constructing gold inlays by the gold or platinum 
 matrix method previous to the announcement of the Taggart inlay have evidently 
 been using praccicallj' the same method of cavity preparation for the Taggart inlay 
 as they have been accustomed to when using the gold or platinum matrix. In 
 making this statement I am judging the mass of our profession by those with whom 
 I have had discussions along this line. 
 
 In using the metal matrix all that was necessary to avoid in cavity preparation 
 was undercuts, for it is obvious that if the matrix could be removed from the cavity 
 without distortion, it could be filled with solder and returned to the cavity and would 
 seat as perfectly as before. This, however, I have found, is not true of the inlay cast 
 from a wax impression. The reason for this is that if the sharp angles are left in 
 
 I'ig. 1 
 
 the cavity they are reproduced in the mold or investment and when the molten metal 
 flows over them it rubs the investment in such a manner as to round these sharp 
 corners, and when the inlay is returned to the cavity it will not properly seat. 
 
 I have found that inlays cast for cavities in the proximo-occlusal surfaces of 
 the bicuspid when prepared by the old method will lack to a considerable degree 
 seating at the gingival border. This observation has been made by numerous 
 other operators and has been accounted for to a considerable extent by the theory 
 that gold shrinks on cooling, but my observation has been that the shrinkage of the 
 gold will not entirely account for the misfit of the inla\-. Again, the floor of the cavity 
 has been left rough and the inlay will not seat because these same indentations are 
 
38 PRACTICAL MANUAL OF DENTAL CASTING 
 
 not perfectly reproduced in the casting, as the very sharp edges are rubbed off by 
 the molten gold as it flows into the mold. 
 
 Figure 1 represents a cavity in the occlusal surface of a lower molar. You will 
 note that all of the angles have been removed from the cavity margins and axial 
 walls and that the floor is perfectly smooth and flat. Note also that the margins 
 are very slightly beveled from within outward, so as to allow a narrow lap of the 
 gold at this point, preventing the pumping out of the cement during mastication. 
 If the cavity was left with sharp angles where the fissures cross and an inlay cast for 
 the cavity, it would not seat or fit, because the sharp angles in the investment would 
 not be reproduced in the inlay for reasons heretofore stated. This would not be 
 true if we had an investment sufficiently hard to withstand the friction of the molten 
 metal. 
 
 Fig. 3 
 
 Figure 2 represents a cavity in the mesio-occlusal surfaces of the bicuspid. Note 
 that the neck of the retention step has no sharp angles to be knocked off by the 
 molten metal flowing into the mold. Note also that where the step joins the a.xial 
 wall that the sharp angles have been rounded with a stone. If we use curves instead 
 of angles at these points the inlays cast to fit such cavities will seat perfectly. 
 
 Figure 3 represents a compound cavity in a bicuspid correctly prepared. Note 
 the sweeping curves and the absence of acute angles. 
 
 IN GENERAL 
 
 If cavities are prepared with small carborundum stones instead of burs there is 
 less liability of producing angles and rough floors, and inlays cast to fit cavities thus 
 prepared have smoother surfaces on the side next the dentine. 
 
 SHAPING WAX MODEL FOR CAST GOLD INLAYS 
 
 By C. E. Abbott, D. D. S. 
 
 The following method is of great value in shaping the wax model: "In com- 
 pound proximal cavities in bicuspids and molars I adjust the medium soft wax to 
 approximate contour and bulk; then I stretch a strip of rubber dam, J^ inch by 2 
 inches over it and against it, holding the ends taut with the left hand. Pressed 
 against the cavity by the rubber dam, the wax is easily burnished to exact proximal 
 contour, occlusal contact, and smooth surface. I then remove the rubber dam, 
 invest and cast as usual." 
 
THE CEMENT LINE IN INLAYS 
 
 By Clarence J. Grieves, D.D.S., Baltimore, Md. 
 
 Note — The writer respectfully refers all interested to his paper, "Cemented Inlays or Contact 
 Fillings, Which?" read before the Mrginia Dental Society, August, 1906, and published in The Dental 
 Summary, which deals with work on the first phase of this subject, and is necessary to an understanding 
 of his position in this article. 
 
 The one leading question foremost in the mind of every operator who attempts 
 restoration of destroyed dental tissues, second only to the removal of the destroying 
 agents and the destroyed and the shaping of caval edges, is whether the final cavo- 
 juncture between filling and enamel will be lasting mechanically to meet stress, and 
 to prevent retention centers for recurrent caries and adhesive chemically to prevent 
 leakage by solution, by sealing these edges; so obvious is the importance of the 
 subject, for it is the final equation in the art of operative dentistry, that this paper 
 needs no further introduction. No matter what the method or filling material 
 heretofore employed, its perfect adaptation required cavo-surface contact excluding 
 mouth juices; edge strength to meet occlusal food impact, supporting caval enamel 
 edges; smooth surfaces to prevent re-attachment of gelatinous carious plaques; 
 extension out into the embrasures to prevent the retention of food and be cleansed 
 by the brush of it in mastication practiced with varying results dependent on the 
 material, location of cavity, skill of the operator, immunity of the patient, etc., etc., 
 we find all of these time-honored requirements for a successful contact operation 
 completely reversed by the advent of the method of the cemented inlay filling. 
 
 Fig. I Fig. II 
 
 Fig. I. From Nyman's "Porcelain Problems," Cosmos, 1905, diagrammatic section showing how 
 washout at "o" in butt-joint porcelain fillings affect color, "e" and "d" section of tooth; e' and d' 
 filling. Note the necessary washout at o'-o of cement c that filling may match. 
 
 Fig. II. Application of the same diagram by writer to gold inlay lap-joint; "a" gold inlay; "b" 
 section of tooth; "d " lap-joint from which there is little loss of cement "c." 
 
 During the inlay period of — say the past fifteen years — long enough in all 
 reason to test a new principle — we note a paradox of both man and method; the 
 same operator who formerly spent hours in attempting these perfect adaptations 
 of gold foil to caval walls is now willing to leave them, to a degree, at least, marginally 
 open to the wash of the saliva; proximally, in the same mouth environment, we daily 
 see porcelain inlays with cemented joints washed out exposing enamel margins, 
 through which the light rays pass into the porcelain, thus, in the only way matching 
 the tooth surfaces which they restore, lying directly adjacent to gold foil operations 
 in perfect contact with similar enamel caval margins. Both operations apparently 
 saving tooth structure, yet based and built upon principles diametrically opposed. 
 
40 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 can both of these methods be right? Are the countless daily converts to the cemented 
 inlay wrong in thus forsaking axioms sanctioned by long experience? The answer 
 to these and many other associated questions is, we believe, to be found in a study 
 of how mechanicall^'-made contact on the one hand and chemically-made adhesive 
 cemented contact on the other will meet and overcome the bite stress and carious 
 environs of the human mouth. As soon as we depart from the teachings of the 
 forefathers, absolute marginal contact of filling material and cavity edges, we find 
 the greatest divergence in principle and method amongst the inlay "cult" in caring 
 for these edges, for while all inlay operators insist on an adhesive cementing media 
 between filling and tooth, the}' sharply divide on the final cavo-surface finish of the 
 filling into: 
 
 "A," Fig. I. Butt-joint operations, necessary' from the friability of the material 
 in all porcelain fillings, where the cementing media is expected to wash out the depth 
 of the -ividth of the joint, ^'^ that the filling may reflect lighc and match; the cavo- 
 surface angle is at right angles, or 90 degrees, as is the filling surface angle; the 
 joint is open to the pump of foods in bite stress when exposed, and to cement 
 solution from mouth fluids. With the finest technique these joints in porcelain 
 inlays can be made only as fine as the thickness of the matrix foil after burnish- 
 ing. Head! says such joints are from 13/^ to 2 1^ times the thickness of the foil 
 
 Fig. III. 
 writer. 
 
 Cuts of filling from Black's "Operative Dentistry." Intirsecting lines made by the 
 
 used (.0001 of an inch); at the best, they are as open as the size of the cement 
 powder granules; this is necessarily limited because extremely fine powder makes 
 cement set so rapidly as to be impractical. Poundstone" found only five out of 
 all the cements studied with powder granules, after solttion in mixing fine enough 
 to permit a joint .0001 ot an inch under 25 pounds' pressure. The butt-joint 
 in gold inlays is subject to all of the doubtful variations produced by contraction 
 of wax and metal and expansion of investing material; if the inlay exactly fits 
 the cavity it will protrude by the distance of the largest cement powder granules 
 which have not gone down in the mix. 
 " B, " Fig. II., Lap-joint operations, possible always from the ductility of the material' 
 gold and its alloys, in all gold inlays, where the marginial cementing media is not 
 expected to wash out for appearances; the cavo-surface angle is anywhere from a 
 little less than 90° to 40°, often topping enamel rods as in best foil operations; 
 the marginal cement is protected from the pump and lave of bite stress and to a 
 
 12. Nyman, J. E.— Porcelain Problems. — Dental Cosmos, IQ03. 
 
 1. Head, J. — Test of the Inlay Cement Problem — Dental Cosmos, IQ05. 
 
 2. Poundstone, G. C. — Discussion of the Cement Problem in Inlay Work. 
 International Congress. 
 
 Proceedings, Fourth 
 
THE CEMENT LINE IN I NLA YS 
 
 41 
 
 degree from mouth fluids by burnishing down the lap to the enamel rods, thus 
 taking up any protrusion made by cement granules in the cement line which 
 does not face the impact of foods, as in hittt-joints, but rather /ac<'^ directly away 
 from it, a great advantage. 
 
 These two great classes must be subdivided again into: 
 First: Those which on section show the cementing media throughout the filling 
 as only a line on the pulpal and axial walls, the filling seated mechanically in 
 the cavity. 
 Second: Those which on section show the cementing media as a line only at the 
 margins, appearing in bulk throughout the filling to ofttimes as much as one- 
 third on the pulpal end axial walls; the filling may have some mechanical re- 
 tention, but more is expected of the cement "en masse" as a retainer. 
 All of these classifications are absolutely necessary, because of the vast difference 
 in behavior of the cement line as between butt' and lap-joints in all mouths; further, 
 it was found early in these observations, which were undertaken some years ago and 
 have been followed up both in and out of the mouth, particularly with honed sections, 
 that while cavities and inlays made by any method were subject as all operations 
 should be to the rules laid down by Black," there were certain exceptions to these 
 
 Fig. IV 
 Fig. IV. "A" butt-joint in porcelain inlay, and "B" lap-joint in gold inlay before exposure 
 to mouth fluids and bite stress; presented for comparison with those showing use in mouth. 
 
 rules, particularly in butt-joints, in the areas of possible damage which are diagram- 
 matically here shown, and may be known as the vulnerable inlay areas, defined as 
 follows: 
 
 Dividing the proximal surfaces, Fig. Ill, of the incisors and canines by a right 
 line, "a-b," which arises just at the gingivus in the labio-gingival angle and cuts the 
 surface, emerging on the lingual surface midway between incisal and gingival; by a 
 second right line, "c-d," which arises at the gingivus in the linguo-gingival angle, 
 cuts the surface, emerging on the labial surface, one-third of the distance from the 
 incisal to gingival; the proximal surface is thus divided into unequal triangles which 
 may be termed the labial, lingual, incisal and gingival triangles, the smallest of 
 which is the lingual. Similarly, the proximal surface of bicuspids and molars. Fig. 
 Ill, may be divided by the line "a-b," which arises at the gingivus in the bucco- 
 gingival angle and cuts this surface, emerging a little gingival to the linguo-occlusal 
 angle, and by a second line, "c-d," which arises at the gingivus in the linguo-gingival 
 angle, crossing the surface to emerge slightly gingival to the bucco-occlusal angle, 
 thus dividing the proximal surface into equilateral triangles, respectively, the buccal, 
 lingual, occlusal and gingival. 
 
 3. Black, G. V. — Operative Dentistry. 
 
42 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 The labial surfaces of incisors and canines and the buccal surfaces of bicuspids 
 and molars may also be so divided by the lines, "a-b," arising for the molars and bi- 
 cuspids, Fig. Ill, at the gingivus on the mesio-gingivo-buccal angle, crossing the 
 buccal surface and emerging at the disto-bucco-occlusal angle, crossed by the line 
 "c-d," which arises at the gingivus in the disto-gingivo-buccal angle and emerges 
 at the mesio-bucco-occlusal angle, dividing the surface into triangles, the gingival, 
 occlusal, mesial and distal. 
 
 For the incisors and canines. Fig. Ill, the line "a-b," arises at the gingivus in the 
 mesio-gingivo-labial angle, crossing the labial surface to emerge at the disto incisal 
 
 Fig. \' 
 
 Fig. V. "A" lingual and "B" labial view of a porcelain inlay in bad mouth environs six years. 
 
 Note the heavy bite stress shown in the enamel of the incisal edges. When set these butt-joints were 
 
 above the average. Note the damage in the vulnerable mechanical areas and all down the lingual; 
 
 the solution at the gingivo-labial angle and yet the washouts were not deep nor was recurrent caries noted . 
 
 angle, crossed by the line "c-d," which arises at the gingivus on the disto-gingivo- 
 labial angle and crosses the labial surface, to emerge at the mesio-incisal angle, 
 dividing the labial surface into triangles, the incisal, gingival, mesial and distal. 
 
 It is obvious that damage to the cement line can come from two sources, viz., 
 mechanically from foods under bite stress, pumping or laving out the cement and 
 
 Fig. VI Fig VII 
 
 Fig. VI. The lingual view of a lateral incisor containing mesial and distal porcelain inlays placed 
 
 at the same time. The mesial "a" lapped the adjacent central and was sheltered from the bite pump. 
 
 Note the fairly good joint at "b" after three years. The distal inlay "c" was thus obviously more 
 
 exposed to the bite with resultant joint damage at "d." 
 
 Fig. \'II. Proximal view same tooth, porcelain inlay "c." Note the very good cement joint on 
 
 the labial at "n." The gingival caries seen in both these pictures is due to rapid recession, is recent, 
 
 and has nothing to do with the crown conditions, which were maintained for three years. 
 
THE CEMENT LINE IN I NLA YS 
 
 43 
 
 joint contents, and chemically from a solution of cement due to acidity of saliva and 
 mucus, whether local or general. The incisal and occlusal triangles include the areas 
 of damage by bite stress, and may be termed the vulnerable mechanical areas; where 
 the lines arise in the labio-bucco and linguo-gingival angles and the incisal half of the 
 gingival triangle are the most dangerous to the cement line from local acidity and 
 may be termed the vulnerable chemical areas. 
 
 Certain areas in normal mouths appear more immune than others to cement 
 solution, as the labial, buccal and small lingual triangles and particularly the lower 
 half of the gingival triangle, which is sheltered b}' a healthy gingivus, of which morj 
 will be said later, for, indeed, it is the only shelter for this line where there is general 
 mouth acidity. 
 
 The application of these lines should not be made too literally, and they cannot 
 be drawn "hard and fast," as they are subject to change in inter-proximal contact, 
 
 rP 
 
 cb I 
 
 ^ n 
 
 ^a 
 
 ^^^J!k^ '^^Hi^. H^^^Hi 
 
 3 
 
 
 \ 
 
 irt 
 
 Fig. VIII 
 
 Fig. VIII. Showing a large mesio-occlusal porcelain contour; superior first bicuspid at "a," 
 which fortunately split in attempting an occlusal section through it. and a disto-occlusal amalgam 
 filling at "b;" "c" represents the cut occlusal portion of the buccal enamel; "d" the cavo-surface 
 enamel parted from "a" and containing some cement; "e" the darkly stained wall from "b" amalgam 
 fillin;. Note the washout on cement line being greater on the bucco-occlusal at "n" than the solution 
 at the bucco-gingiyal angle at "m" from acidity. 
 
 gingival recession and the curvature of the embrasures for the proximal, and lip and 
 cheek contact for the labial and buccal, but they give a most valuable general idea 
 to the operator in cavity preparation. 
 
 For instance, if we take the classification of butt and lap-joints and apply the 
 rules of these areas we find from the study of a large number of specimens both in 
 and out of the mouth, that in: 
 
 Butt-joints, Fig. IV A, usually porcelain inlaws, after a period in the mouth 
 dependent on mouth conditions to be mentioned later for Proximal Cavities in In- 
 cisors and Canines, just as the operation invades the vulnerable mechanical area or 
 incisal triangle. Figs. \T and VII, so is the cement pumped out sometimes to the 
 entire depth of this triangle, or one-third the axial walls, Fig. V A; no matter how 
 slightly the joint is exposed in the area to the lingual there is always loss of cement 
 frequently clear through to the labial wall, with consequent loss of cavo surface enamel 
 and filling edges, Fig. V B ; there is one exception in these areas where large restorations, 
 as the whole incisal third in canines and incisors or occlusal third in bicuspids, are 
 
4-1 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 made in porcelain; here butt-joints do well on the buccal and lingual in bicuspids 
 and the labial in incisors and canines where parallel to the incisal and occlusal sur- 
 faces the cement line is sheltered from the bite pump by a wall of porcelain opposed 
 above it; the Hngually-exposed joint is quickly pumped out and soon stands as does 
 the enamel, alone. 
 
 Proximal Cavities in Bicuspids and Molars — Here, with even greater force , the 
 rule for mechanical areas applies to the occlusal triangle. Fig. VIII; frequently gold 
 inlays with butt-joints are seen in this location, but whether gold or porcelain we 
 find the cement pumped out down along the axial wall, often over the pulpal wall, 
 and always washed entirely from the bucco and linguo-occlusal angles. 
 
 Labial cavities jor incisors and canines in the incisal triangle — The cement line 
 does well except in erosion mouths (to be classified later), where the cave surface 
 margins disappear as though brushed away leaving the filling "high and dry." 
 FiR. IX. 
 
 AH 
 
 
 
 c B "^ ^ 
 
 
 
 
 
 B| - ^ni "*" \ <f ^ 
 
 
 
 
 b a. ^e 
 
 Fig. IX 
 
 Fig. X 
 
 Fig. IX. Lateral incisor, large porcelain inlay at "a," time in the mouth about five years; co- 
 hesive gold filling at "b'' placed some years before porcelain; stained with eosin, cut to section line 
 x-y and honed; mouth of the erosion type. 
 
 Fig. X. Section cut at x-y retained in cement "a." Porcelain inlay section at "c," enamel and 
 dentine at "b," gold filling section at "d;" dark area, stained cement at "e." Note the depth of 
 washout at "g" and leakage and recurrent caries at "h." 
 
 Bicuspids and molars — In the occlusal triangle the line suffers from bite stress 
 just in proportion as the inlay invades that triangle, and as the tooth, particularly 
 the inferior, tilts to the occlusal, Fig. III. 
 
 Caries can and does recur after this laving process. Fig. X, when shelter is 
 afforded for attachment of plaques, deep under the caval walls; the rule being that 
 when the cement has laved below the depth of the enamel rods in mouths prone to 
 caries, it begins at any shelter on the axial dentine. 
 
 Butt-joints — In the vulnerable chemical areas named, the labio-bucco and 
 linguo-gingival angles and the upper half of the gingival triangle, or, in other words, 
 in the usual retention centers dangerous to all contact operations, the cement line 
 suffers. Fig. XI, from recurrent caries every time a chemical solution of cement 
 occurs to the depth of the enamel. Fig. XII, but the percentage of its occurrence to 
 any great depth is much smaller than the "wash-outs" in the vulnerable mechanical 
 
THE CEMIiNT LINE IN INLA YS 
 
 45 
 
 areas, just as the percentage of recurring decay is very much less for inia>s than for 
 contact operations in these dangerous areas, F"ig. XIII; this we may account for later 
 dependent upon a number of modifying factors, local and general. 
 
 This is just where the variation for inlays previously mentioned comes in, 
 from the rules of Black, for contact operations; due to this fact it is here laid down as 
 a rule that in butt-joints, or, in other words, porcelain inlays, for no judicious operator 
 
 Fig. XI 
 
 Fig. XII 
 
 Fig. XI. Small disto-proximal filling left superior canine stained with epsin; in use twelve years; 
 "a" enamel, "b" porcelain filling. Note that the same drying crack "c," which split the enamel after 
 excision, continues on through the filling, and the filling is well retained, notwithstanding the ugly 
 washouts at "d." 
 
 Fig. XII. A section cut out of same tooth and filling on through the labial at "a" to show the 
 state of the caval cement, which is good at "b," and the dangerous looking washout shown at "d," 
 Fig. XI, are of little depth, the eosin stain having gone only as far as "c." 
 
 would use a butt if he could make a lap-joint, the cement line should not be extended 
 any further out into the embrasures proximally, and particularly not extended into 
 the incisal and occlusal triangles, than is absolutely necessary for removal of damaged 
 tooth structures; in other words, the butt-joint operation should be "extended to 
 
 Fig. XIII 
 Fig. XIII Section without staining cut through proximal porcelain filling, lateral incisor; time 
 in mouth, 1,3 years; "e" enamel, "d" dentine, "r" pulp cavity, "p" porcelain filling. Note the per- 
 fect condition of the cement at "c," notwithstanding the open washouts at "a" in the butt-joint, 
 which has undoubtedly been protected by the contained film. 
 
 prevent" as little as possible, Fig.X'lII, as there is more danger from the mechanical 
 areas named in "pump out" of cement. Fig. V, than in the chemical areas named 
 from solution of cement, Figs. VI and VII, all of which is directly opposed to the 
 correct rules for contact operations. 
 
 Mention has been made of the shelter afforded under the normal gingivus, for 
 here the butt-joints, as indeed joints of all operations, arc at their liest, and a word 
 
46 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 is necessary as to the causes for that immunity. In a report made on "The Behavior 
 of Certain Metals in the Mouth,"* the writer found all vulnerable metals as gold 
 alloyed with zinc in solders and gold-plated german silver, as "D" bands in ortho- 
 dontia, showing deep destruction of the metal just at and above the gingival margin 
 and perfect conservation of the metal as when first placed below the gingivus; this 
 occurred only in the normal gingivus; any irritation from fitting the band interfered 
 with this function, when the metal was quite as much eroded as that exposed to the 
 dangerous line directly above the margin. 
 
 It was further proven that vulnerable metals, when in fixed actual, but not 
 pressure contact with the mucosa were not affected by the degeneration from mouth 
 juices, which quickly attacked them at exposed parts; this was shown by a series 
 of experimental bridges, the saddles of which, made of vulnerable metals, were placed 
 in contact with the membranes covering the ridges; removed and examined from time 
 to time it was found that they were clean and undamaged, where in good contact, 
 but the exposed edges buccally and linguall}' were eroded. It was reasoned and so 
 reported," that this immunity might have been due to the alkalinity common to all 
 
 Fig. XIV. From Conzett's article. "Gold Inlays," Items oj Interest, to show ideal lap-joint at 'a." 
 From Black's "Operative Dentistry," wrong lap for foil operation but right lap for gold inlay at "a." 
 
 normal mucosa, but more than likely it is an illustration of the immunity conferred 
 on all of the mouth mucosa by the constant chemictoxis of the leucocytes. Movable 
 membrane contact is most damaging in carious environs, witness the record written 
 on many buccal surfaces cf permanent molars as they erupt and are exposed to it in 
 the child mouth — due to the retention afforded by the cover cf the commissures. 
 The long record cf both butt and lap-jcints in crowns carefully set without irritation 
 under the gingivus, is most convincing; the cement line will stand under the protec- 
 tion of the gingivus in the butt-jcints cf comparatively flat copes of all porcelain 
 crowns and in the lap-joints cf banded crowns, the best cf which are far inferior to 
 the poorest joint made in the inlay; this might be explained, to a degree, by the pro- 
 tection afforded the cement by crown contour from bite stress, but for the fact that 
 as soon as gingival recession occurs, caries recurs promptly proximally, which is also 
 true of all operations in this locality in carious mouths. But whatever the cause for 
 this immunity afforded by the normal gingivus, all agree that it exists, and that all 
 operations should be put under its cover without damage to it, when possible. 
 
 Lap-joints, Fig. IV R, when correctly made with the metal ductile enough and 
 in sufficient bulk to be well "spun" and burnished over the cavo surface angle retain- 
 ing and protecting the cementing media, this grinding over and burnishing doing 
 
 4. Grieves, C. J. — The Behavior of Certain Metals in the Mouth. Proceedings, National Dental 
 Association, 1909. 
 
 5. Grieves, C. J. — A Review of Bridge Work. — Dental Brief, Sept., 1910. 
 
THE CEMENT LINE IN INLA YS 
 
 47 
 
 damage to but the finest external line of cement, the rest of which is protected thereby, 
 Fig. XIV, are the writer's ideal, and in his judgment, a long step to the final solution 
 of this problem, Fig. XV; after a long and careful study of lap-joints tested side by 
 side with butt-joints, often in the same filling. Fig. XVII, in both the mechanical 
 
 Fig. XV 
 
 Fig. XVI 
 
 Fig. XV. Section gingival tliird gold inlay disto-proximal right superior central, showing ideal 
 butt-joint conditions; "a" gold inlay; "b" dentine and cement, "c" butt-joint. 
 
 Fig. XVI. Section at the linguo-occlusal angle superior first bicuspid, showing successful long 
 lap joint of a gold inlay, mouth environs bad; time, nearly four years; "a" cross section of enamel of 
 the linguo-occlusal angle, "b" lap joint, "c" body of inlay, "e" cement in joint complete almost to 
 cavo-surface angle, "d" investing cement to retain parts while honeing. 
 
 and chemical areas, they present conditions which are most satisfactory. Fig. XVII. 
 There is little or no loss of cement from the lave of bite stress, for the reason that it is 
 sheltered under the cover of the properly finished "lap," hence we may follow the 
 laws of Black and extend occlusally. Fig. XVI, and into the embrasures; again, when 
 the lap is properly finished — at no time an easy thing — the loss of cement by solution 
 
 Fig. XVII 
 
 Fig. XVII. .A — Lingual view of a mesio-disto-occlusal gold inlay, right superior first molar in 
 use six years; "c" gold inlay surface, "b" caval cement in good condition because of perfect protection 
 of the lingual wall by good lap joints at "a." 
 
 B — Caval view of same filling. The caval cement is intact on the lingual filling surface at "n" to 
 the line x-y dividing the inlay mesio-distally. The buccal wall was protected only by a butt-joini- and 
 it will be noted that all of the caval cement buccal to the line x-v is either washed out or stained at " m. 
 
48 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 in the dangerous chemical areas is slight, while, of course, in these areas, under 
 certain mouth conditions, all operations fail, they stand up just as much better to the 
 attack as the butt-joint stands better than the contact operation, Figs. XVII and 
 XVIII. The metal in the lap-joint must meet all requirements for perfect contact 
 finish; there is only one such, in the opinion of the writer, and that is pure gold, 
 alloying of which seriously interferes with marginal adaptation, just as it does in foil 
 operations, Fig. XIV; in fact, one of the principal arguments for the lap-joint is to 
 be found in its perfect protection of the enamel rods of the cavo surface angle. The 
 failure of the lap-joint is largely one of technique, and occurs, strange to say, just 
 where the butt-joint is at its best, under the normal gingivus; a greater number of 
 failures are here to be reported than at any other point, for the evident reason 
 that the correct setting and finishing of the lap under the gingivus without damage 
 thereto or "over- flange," causing retention, is one of the most difficult procedures 
 in operative dentistry. Fig. XIV, and needs much betterment. i-' 
 
 It might be appropriate in this connection to mention the method applied by 
 Levi C. Taylor, for small operations, as of building the filling of gold, usually of the 
 
 Fig. XVIII 
 
 Fig. XVIII. A — Looking into an occlusal cavity in a molar filled four years with lap-joint gold 
 inlay, of which a section has been cut at the disto-buccal cusp, showing perfect condition of cement at 
 "a," in fact, through the whole cavity. 
 
 B — View of the linguo wall of the inlay which filled cavity shown in A. Note the lap joint which 
 has stood heavy morsal stress with the loss of but little cement at "a," the rest of the cement "b" is 
 in good shape. 
 
 crystal types, in the midst of setting cement to a moderate lap-joint, Fig. XIX; a 
 number of such have been examined, and they seem to combine the advantage of 
 both the inlay and contact operations, also amalgam fillings after this method built 
 of quick-setting alloy in slow-setting cement, Fig. XX, with the help of an oiled 
 matrix, finishing to the least bit of a lap of the cavo-surface angle; under particularly 
 unfavorable mouth conditions these fillings do well, and the writer believes that every 
 amalgam filling should be thus cemented in. 
 
 Reference has been made to the vulnerable chemical areas, and we find mouths 
 where all areas are vulnerable, in others chemical solution is localized; when we realize 
 that the cement-line is continually bathed in saliva, a fluid constantly changing to 
 reflect systemic conditions, some classification of mouth types, broad and necessarily 
 defective, though it may be, is here necessary, to a further study of the subject. 
 While comparatively little is known of mouth conditions — for instance, caries of the 
 enamel is yet unsolved — certain data is at hand, thanks to the efforts of many 
 
 13' Lane, J. G,— 'A Compg^rison of Differences of Opinion, — Denial Brief, Feb., 19U, 
 
THE CEMENT LINE IN I NLA YS 
 
 49 
 
 authorities, particularly Miller, Williams and Black, Michael, Kirk and Low, and 
 the writer presents this diagrammatic scheme with apologies to these investigators. 
 We may divide mouth types systemically into the Normal, the Hypo-acid and 
 Hyper-acid, as follows: 
 
 Scheme of Mouth Types as 
 
 NORMAL 
 
 MOUTHS — Can be kept clean. 
 
 SYSTEMIC CONDITION — Biochemical 
 changes equally balanced. 
 
 SALIVA — Neutral or alkaline. 
 
 MUCUS — Alkaline; medium in amount exist- 
 ing independently in ropes depositiuR on 
 all surfaces. 
 
 SULPHOCYANATES— Normal, glycogen and 
 ammonia little or none. 
 
 CARIES — Medium in amount, dark and slow. 
 
 EROSION— None. 
 
 SALIVARY CALCULUS— Medium at the 
 usual point. 
 
 SERUMAL CALCULUS— None, frequent sul- 
 phid and other stains. 
 
 FILMS ON TEETH — On all surfaces e.xcept 
 occlusal; alkaline or acid according to per- 
 centage of glycogen, protective e.xcept in 
 retention centers. 
 
 INLAYS do well, and butt-joints stand, but 
 often stain; suffer most in the stress areas, 
 slightly in the retention centers. Figs. 
 V, VI, VII, XI, XII, XIII, XXI. 
 HYPER-ACID 
 
 SYSTEMIC CONDITION— Oxidation low; 
 increase in organic acids; Biochemical 
 changes slow; Arthritism, showing in two 
 phases. Erosion and Pyorrhea. 
 
 "A" EROSION MOUTHS— Which look "too" 
 clean. 
 
 SALIVA — Acid from acid sodium phosphates, 
 clear and limpid. 
 
 MUCUS — None, that secreted is in solution. 
 
 SULPHO CYANATES in excess. 
 
 GLYCOGEN below and AMMONIA above 
 normal. 
 
 CARIES— None. 
 
 EROSION — In excess on cheek or lip contact. 
 
 SALIVARY AND SERUMAL CALCULUS— 
 None, no sulphid nor other stains. 
 
 FILMS ON TEETH — A few growths open to 
 the wash of saliva. 
 
 INLAYS — Look well but fail, particularly butt- 
 joints from all around solution of cement 
 
 Associated with the Systemic State 
 
 due to the acid-sodium salts; other opera- 
 tions do well. Figs. IX. X and XXII. 
 
 "B" PYORRHEA MOUTHS— Teeth dirty 
 cer\'ically from gingival waste and calculi. 
 
 SALIVA — Alkaline from tissue waste. 
 
 MUCUS — Sulpho-cyanates, glycogen and am- 
 monia above the normal. 
 
 CARIES — Little, considering the numerous re- 
 tention centers caused by gingival recession. 
 
 EROSION— None. 
 
 SERUMAL AND SALIVARY CALCULUS— 
 In excess and recurring; staining from all 
 causes. 
 
 FILMS ON TEETH— "Materia alba." greasy, 
 alkaline. 
 
 INLAYS and all fillings do well except in 
 marked retention centers; butt-joints stand 
 almost as well as lap-joints, but stain. 
 
 HYPO-ACID 
 
 DIRTY MOUTHS— Cannot be kept clean. 
 
 SYSTEMIC CONDITION— Oxidation high- 
 decrease in organic acids; increase in ex- 
 cretion of saline chlorids. 
 
 SALIVA — Neutral as secreted but acid, thick 
 and ropy; odor and color from the Mucus 
 — ivhich is abnormal, containing a high 
 percentage of carbohydrates as excreted, 
 highly acid, forming sordes. 
 
 SULPHO-CYANATES— .-Xud ammonia below 
 normal. 
 
 GLYCOGEN — Greatly in excess. 
 
 CARIES — Excessive, rapid, white, and always 
 recurs, no matter what the operation. 
 
 EROSION— None. 
 
 SALIVARY CALCULUS— In excess. 
 
 SERUMAL CALCULUS— Occasionally, sul- 
 phid and other stains in excess. 
 
 FILMS ON TEETH— A "thick acid felt" 
 everjvvhere; the ideal media for B. acidii 
 lactici. 
 
 INLAYS WITH LAP-JOINTS do better than 
 contact operations; butt-joints fail quickly, 
 caries recurs at all points on all operations 
 
 While it is most desirable that the individual operator should ha\e an intimate 
 knowledge of salivary analysis, so intricate is the subject at present it is hardly to 
 be expected that he can apply it to his daily work; the foregoing scheme shows the 
 principal mouth types, and a close obser\^er may, by carefully noting conditions, 
 read the record written on the teeth and gingivus as a geologist reads the rock.= 
 ^nd reach a fairly accurate conclusion of existing mouth conditions, 
 
50 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Thus, it will be noted from the foregoing, that caries does not recur in the mouths 
 of erosion at alt and rarely in those of pyorrhea in the division classed systemically as 
 Hyper-acid, that for instance, in the erosion types there is a coincident lack of the 
 carbohydrate element and an excess of sulpho cyanates coupled with an absence or 
 rapid solution of mucus, the saliva is acid because of the acid sodium and calcium 
 salts secreted as a content of the mucus, a systemic acidity. 
 
 On the contrary, in the mouths classed systemically as Hypo-acid, dental 
 caries is rampant; here the carbohydrate element is far in excess, as is the mucus, 
 which is abnormal in quantity and quality, being thick and ropy, with the sulpho- 
 cyanates coincidentally below normal, the saliva is again acid from the decomposi- 
 tion of the carbohydrate element excreted with the mucus; a general bacterial acidity. 
 Lying between these extremes, and gradually merging into each, according to the 
 variation in diatheses, is the normal, where the body processes, and consequently 
 the excreta, through the saliva, are equally balanced, the saliva is alkaline or neutral 
 in reaction, caries occurs, but does not recur except when retention centers are pro- 
 duced for the decomposition of carbohydrate foods, producing areas of local acidity. 
 
 Fig. XIX 
 
 Fig XX 
 
 Fig. XIX. A — Section cut through an occlusal filling of crystal gold condensed into setting 
 cement, extracted and stained; "a" gold filling, "b" cement which is perfect. Note the conditions 
 at the cavo-surface angles. 
 
 Fig. XX. Similar section through an amalgam filling made after the same method, same time in 
 the mouth, similarly stained; "a" amalgam, "b" cement, owing to contraction of amalgam stains at 
 "c", but no caries. 
 
 As all junctures between filling and tooth, and butt and lap-joints are no ex- 
 ception to the rule, bear much the same relation to incipient caries, as do enamel 
 faults and fissures, often creating immediately retention centers of the worst type, a 
 better understanding is needed of the enamel surfaces, and more particularly as to 
 what actually covers them to the dissipation or conservation of the cement line; 
 the writer is fortunate in being able to recall to your minds these conditions in words 
 other than his own. 
 
 Miller'' tells of a film of micro-organism which covers the surfaces of all teeth, 
 from 100 taken at random out of 1,000 teeth in two different experiments, and 
 stained by eosin and the Gramm method, he says: " I was surprised ac the universal 
 presence and extent of the films; of the molars and bicuspids, only the cusps, and 
 usually a small portion of the buccal, and less of the lingual surfaces, were found 
 free from films; of the incisors and canines, the labial surfaces showed a film without 
 a single exception; at the neck of the tooth, where the enamel was completely pro- 
 tected by the gum, there was no film. * * * Fissures, grooves, pits and depres- 
 
 7. Miller, W. D. — The Presence of Bacterial Plaques on the Surfaces of the Teeth and their Sig- 
 nificance. — Denial Cosmos, 1902. 
 
THE CEMENT LINE IN INLAYS 
 
 51 
 
 sions of all kinds are indicated by deeper staining and denser films. I was curious 
 to see how the teeth of my colleague, Dr. York, who is immune to caries, reacted. * 
 * * * on the whole, Dr. York's teeth, being carefully kept and highly polished, 
 show the film restricted chiefly to the cervical portions and proximal surfaces." 
 
 Fig. XXI 
 
 Fig. XXI Caval and lingual views of a large porcelain contour in a normal mouth about two 
 years. 
 
 A — The gingival seat. Note that the only loss of cement is at "b," where the porcelain is exposed 
 from solution just at the gingivus; "a" cement intact. 
 
 B — The entire pulpal wall from x gingival to y incisal; the cement "a" is perfectly preserved 
 except at "b," where it is stained from exposure due to pump from bite stress in the incisal triangle. 
 Note the little solution on the labial wall at "c" as compared to the deep washout at "b." 
 
 C — The lingual view showing contour, and loss of cement shown in A gingivally. 
 
 Again he says, in answering the question. Are the bacteria films or plaques re- 
 stricted CO carious teeth? "The question is very easily answered in the negative. 
 They are not characteristic of carious teeth, but of dirty teeth or rather of teeth whose 
 
 Fig. XXII 
 (Compare with Fig. XXI.) 
 
 Fig. XXII. Caval and lingual views of a large porcelain contour in a mouth of the erosion type, 
 about two years. 
 
 A — The gingival seat. Note the great loss of cement at "b" in the two gingival angles where 
 exposed to acid saliva and its protection by the gingivus at a'; the character of the caval cement at a(2) 
 is not as good as in A, Fig. XXI. 
 
 B — The entire pulpal wall from "x" gingival to "y" incisal; the cement "a" is in poor shape, 
 having lost its retentive value; at "b" it is stained for the same reasons as in B. Fig. XXI; it is com- 
 pletely lost along the entire labial and lingual at "c" and "d," allowing entrance of light rays, producing 
 perfect color but proving the solvent power of a saliva loaded with acid sodium salts. 
 
 C — The lingual view showing contour and complete loss of cement from "n" to " m " on the 
 linguo-gingival anple. 
 
52 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 surfaces are not kept perfectly cleansed by either natural or artificial friction. Teeth 
 which are not kept clean by the process of mastication; teeth without antagonists; 
 loose teeth which oscillate in the mouth, are covered with greasy deposits ("materia 
 alba" of Leeuewenhoek) show most abundant growths; in fact, it would be very 
 difficult to find teeth which did not show bacteria adhering to the surfaces at some 
 point or other." 
 
 Later he saj's, ' ' We may put it down as an axiom that films will be found wherever 
 the surfaces of the teeth are not kept free from deposits of mucus, epithelium, food, 
 etc.," Fig. XXIII. 
 
 Lastly, in discussing the existence of the gelatinoid plaque, he remarks: "If the 
 food accumulated on the surfaces or in the cavity undergoing fermentation, it is 
 readily conceivable that a special growth of bacteria in immediate contact with 
 the surface of the teeth would intensify the action at that point, though fermentation 
 itself would certainly not be solely dependent on such growth; if there is an accumula- 
 tion of nitrogenous food, or if the surface of the tooth is coated with a greasy layer of 
 
 A 
 
 1 
 
 ^0- 
 
 
 
 1 
 
 
 ^_ 
 
 
 1 
 
 
 X 
 
 / 
 
 " 
 
 - -. ::■ - ^ 
 
 m 
 
 
 ^m 
 
 
 L 
 
 
 
 
 ..,„.^„,„„ 
 
 Fig. XXIII 
 
 Fig. XXIII. From Miller's "The Presence of Bacterial Plaques on the Surfaces of the Teeth and 
 Their Significance," Cosmos, 1902, showing that films may occur without caries. 
 
 mucus, epithelium, etc., there will be putrid decomposition with alkaline reaction, 
 which again may be most intense directly on the surface. In such cases it is con- 
 ceivable that the film might serve as a protection to the tooth." (The italics are mine.) 
 
 You will note that Miller describes these films as covering all teeth, normal as 
 well as carious, the film consisting of mucus (to which Kirk, Lohman, etc., give 25% 
 carbo-hydrate and 75% nitrogenous-moiety), epithelial scales, organism, etc., so 
 the decomposition of this film in the normal would be a nitrogenous material, putrid 
 and alkaline, protective in all but the retention centers for carbo-hydrate foods, 
 which would then raise the acidity to the point of decalcification, but if the 
 percentage of carbo-hydrate in the mucus is raised, as in the Hypo-acid diathesis, 
 lactic acid fermentation takes place in the film and caries becomes general, unless 
 the acid is diluted by the entrance of saliva, due to the porosity of the film. 
 
 It is interesting in this connection to quote J. Leon Williams on these films under 
 carious condition. He says: "I have ground more than four hundred sections of 
 enamel in every stage of decay of the teeth — in one respect every specimen has shown 
 precisely the same appearance; lining cavities or covering surfaces where decay has 
 
 8. Williams, J. Leon. — A Contribution to the Study of Pathology of Enamel. — Denial Cosmos, 1897 
 
THE CEMENT LINE IN INLA YS 
 
 5^ 
 
 c(jnimenceil, there is always to be seen a tliirk felt-like mass oi aciil, lonning micro- 
 organisms. This mass of fungi is so dense and adhesive as to make it highly im- 
 probable that enamel is affected except in rare or special instances by any acid other 
 than that which is being excreted by bacteria at the very point where the enamel is 
 attacked." Fig. XX IV'. 
 
 It will be seen from the above that Williams studied the film in the abnormal. 
 He will not admit that this film may be permeated by a general mouth acidity except 
 "in special instances," one of which we take to be erosion types mentioned before, 
 where the films do not exist at all, or are very slight, the saliva being acid from the 
 acid-sodium salts, the mucus which goes to make films being held in solution; it is 
 interesting to note that these are the very types where the cement line fails most 
 rapidly, so that it would appear that the film is protective of the cement line unless, 
 as he says, acid be formed in and under it or "at the very point where enamel is 
 
 Fig. XXIV 
 
 Fig. XXIV. From J. Leon Williams' "A Contribution to the Study of Pathology of Fnamel," 
 Cosmos, 1897, showing film present on all teeth. 
 
 attacked" under the cover of the film, and this again is most con\incing, for it is the 
 other and opposite type of mouth acidity, the Hypo-acid, where the carbohydrate 
 percentage in the mucus is so high as to produce acid fermentation in the film. 
 
 Black disagrees sharply with Williams in associating all films with caries, saying: 
 "It seemed that he included all manner of material that contained micro-organisms 
 (practically any material clinging to the teeth contains them), going wide of the line 
 of those forms known to produce caries. He seems also to have included deposits 
 through which water would run so easily that they would be no bar to the washings 
 by saliva; such coatings are found plentifully over the surfaces of teeth of immune 
 persons, and also in others where there is no decay of enamel. Careful study shows 
 that many kinds of deposits upon the teeth present similar appearances when seen 
 in microscopic section to those produced by gelatinous plaques and 3'et seem to have 
 no influence whatever on the localization of caries''," Fig. XX III. 
 
 Blacki" agrees with Williams that general mouth acidity cannot produce caries, 
 
 10. Black, G. V. — Discussion of Miller's Paper: "A Study of Certain Questions Relating to the 
 Pathology of the Teeth." Proceedings, Fourth International Dental Congress, Vol. I. 
 
54 PRACTICAL MANUAL OF DENTAL CASTING 
 
 and insists that caries is due to a special gelatinoid plaque, saying: "I want it 
 understood that I mean a gelatinous substance. I do not mean accumulations of 
 micro-organisms loosely held together on the surface of the tooth * * * in- 
 spissated mucus * * * greasy accumulations or any of these things; I mean 
 a substance that is gelatinoid or gelatin-like * * * not soluble or meltable as 
 gelatin". I have grown the plaque artificially, have seen it in large numbers, and I 
 am sure that under certain dietetic conditions it is produced." 
 
 Miller and Black thus boch agree that films cover all teeth and do not necessarily 
 mean caries. 
 
 Finally, Kirk" condenses the whole matter thus: 
 
 "The catchy formula that 'clean teeth will not decay' is misleading, even if true 
 in the ideal sense * * * first, because it is equally true that unclean teeth do 
 not necessarily decay; and, second, it is practically impossible to always have clean 
 teeth in the ideal sense. * * * For the reason just stated, dental caries cannot 
 logically or scientifically, any more than from the standpoint of observed facts, be 
 classed as a filth disease. * * * More particularly has attention been called to 
 the fact that fermenting particles of carbohydrate food debris adhering to tooth 
 surfaces is not in itself sufficient to account for the phenomena of caries of the teeth; 
 that the mixed saliva itself contains fermentable substances as it is excreted from the 
 glands, and that this carbohydrate product of nutrition dialyzed from the blood 
 plasma is the element found in the saliva of caries susceptibles which is the normal 
 pabulum of the lactic acid bacteria concerned in the first stages of tooth caries * * 
 salivary composition is a resultant of nutrition, and that in its turn is dependent in 
 a large degree upon food habit." 
 
 It is thus shown that the chemical composition of the saliva and the growth 
 and chemical composition of the films forming upon enamel surfaces is dependent 
 upon the nutritional state, and this is most impressive when we find that the cement 
 line is damaged most rapidly and without caries in the erosion mouths of the Hyper- 
 acid diathesis, where there is coincident acidity of saliva and solution of mucus with 
 few films; that it suffers almost as much, attended this time by rapid caries, in the 
 mouths of the Hypo-acid diathesis, where there is coincident acidity of saliva and 
 excessive mucus, acid from its fermenting, carbo-hydrate content forming a thick 
 "felt" of acid films. Fig. XXIV, and finally, it is damaged least of all in the normal 
 mouths, where the saliva and mucus are alkaline and films grow freely, but are 
 alkaline from putrefaction of the normal nitrogenous content. Fig. XXIII. 
 
 It would thus appear that there is also something mechanically protective 
 against mouth fluids in normal mucus and its films when the film is not acid-produc- 
 ing in itself, Williams saying, "This mass of fungi is so dense and adhesive as to make 
 it highly improbable that enamel is affected by any acid other than that which is 
 being excreted by bacteria at the very point where enamel is attacked," and Black 
 insists on the tough adhesive agglutination to enamel surfaces of the gelatinoid 
 plaque, maintaining that no dilutions can occur from the fluid of the saliva under' 
 these growths. Fig. XXIV. 
 
 So we take it as proven that the only danger to the cement joint would be the 
 excessive acidity of the contained film ; the total absence or the continued displacement 
 of the film, or so slight a growth as to allow entrance of a generally acid saliva, and 
 
 9. Black, G. V. — Discussion, Report of the Committee on Scientific Research, Dental Society, State 
 of New York — Denial Cosmos, 1906. 
 11. Kirk, E. C. — Editorial: Prophyla.xis. — Denial Cosmos, Feb., 1911. 
 
THE CEMENT LINE IN INLA YS 55 
 
 while Black says, "The acidity of the general saliva does not become sufficient to 
 cause caries. Those immune to caries have saliva fully as acid as those intensely 
 susceptible,"^ it must be recalled from the work of Hinkins and Head that cement is 
 much more vulnerable to mouth acids than is enamel. 
 
 Relative to the dangers of oral mucus, you are referred to the workof Lohman, 
 who claims that mucus is the direct acting cause of all carious processes, and to 
 Kirk' ''and Miller's' ''discussion of this theory, with which they do not at all agree 
 only in so far as has been previously quoted; the writer*" believes that " If mucus were 
 destructive rather than preservative of enamel continuity, teeth in our race would 
 cease to exist, so thoroughly are they encased by it." Of course, this is the normal 
 mouth mucus, the same no doubt to which Head' refers when he says of the cement 
 line, "The mucus gets into the fine line and acts as a capillary plug, preventing the 
 constant interchange of solvent fluids." 
 
 The presence of a protective film in inlay joints under certain conditions now under- 
 stood cannot be Questioned; as to just hotv the film protects the contained cement, that 
 needs further investigation. 
 
 It is the writer's idea that films fill the crevice left by the earliest washout of the 
 superficial cement almost as soon as the inlay is set, and, as soon as they are retained, 
 alkaline putrefaction begins and the contained film becomes alkaline and discolors; 
 if the film is of sufficient density and agglutination, the cement line is protected until 
 the film is displaced, Fig. XIII. If the mouth be of the Hypo-acid diathesis, with 
 its high percentage of carbohydrate in the film, acid fermentation occurs in the 
 contained film, the lactic acid attacks the cement, which is alkaline, to solution 
 until the acid is neutralized and the film becomes alkaline and protective; if this is 
 displaced, as is often the case, the process repeats itself until the "wash-out" becomes 
 so deep and the renewed film so acid, that it cannot be neutralized by the dissolving 
 cement under it, when decalcification of the cavo-surface enamel occurs and caries 
 begins. 
 
 It might be argued that the ordinary decalcification of enamel would also neutral- 
 ize the acidity of the attacking film, and that caries should then cease, and it does, but 
 only to begin again, as all know who have attempted carious cultures; for when the 
 percentage of acidity of the culture media gets too high it must be neutralized b\- a 
 slight addition of alkalines; it is just this intermittent alkalinity which makes caries 
 of enamel possible, but the amount of alkalinity produced by slow caries of enamel 
 is small when compared with the acid neutralization possible in rapid cement solution. 
 
 There are as many stages to this process of maintaining the alkalinity of the con- 
 tained film as there are gradations from the normal, from the simple neutralization 
 of a slightly acid film, and its agglutination and retention to the dangerous combina- 
 tion in the -vulnerable mechanical areas named, where the cement and contained 
 films are pumped out by bite stress, only to be replaced by other deeper acid films, 
 and so on to complete joint destruction. 
 
 This is the usual history of the destruction of the ordinary cement filling: in the 
 occlusal areas it is washed and the film rapidly removed; in the gingival areas the film 
 is retained, but in such mass and constantly changing that it is neutralized by the 
 
 15. Lohman. A. — A Ngw Fact About Dental Caries. — Archiv.. June. 1904. 
 
 16. Kirk, E. C. — Editorial: "Mucin as a Factor in Dental Caries." — Denial Cosmos, 1904. 
 18. Miller, W. D. — New Theories Concerning Decay of Teeth. — Denial Cosmos. 1905. 
 
 6. Grieves. C. J. — Report of Work on Base vs. Noble Metals in Orthodontia. — Items of hilerest, 
 Feb.. 1910. 
 
PRACTICAL MANUAL OF DENTAL CASTING 
 
 alkalinity of the dissolving cement only to be replaced by a larger film of higher 
 acidity, and there is no retention of film. From a protective standpoint, agglutina- 
 tion of the film and its retention are the most necessary things in inlay work, as shown 
 by all these investigations, and, clinically, the rule holds good, viz., the finer the 
 joint, the less the film; if it be acid, the less to neutralize, and the better the retention 
 of it. 
 
 It is now easy to understand how the finest contact operations may fail Avhile 
 the ordinary cement-joint may stand in the same embrasure, for if the contact opera- 
 tion falls short at any point of absolute contact, capillarity acts, fluids enter, and the 
 crevice fills with acid film. Fig. XXV, which so slowly attacks the cavo-surface enamel 
 that the contained film, instead of being neutralized, receives just the percentage 
 of alkalinity sufficient to maintain caries; in the cemented joint, as has been shown, 
 the acidity of the film acts quickly on the more susceptible substance present, the 
 cement, and the film is made alkaline, Fig. X, XI, XII, XIII. 
 
 With all these facts in mind the operator may approach a mouth for inlay work 
 with some assurance of his knowledge, first of the diathesis, and by that judge how 
 
 Fig. XXV 
 
 Fig. XXV. A — Linguo-incisal view of one of the best malleted gold contours the writer has ever 
 examined, lioned to the dentine; "a" dentine, "b" gold filhng. Note the stain from leakage at "c" 
 in the vulnerable incisal angle; time in the mouth, eight years. 
 
 B — A cross section cut through a bicuspid from bucco-gingival to linguo-occlusal of the best amal- 
 gam filling yet seen by the writer; "a" dentine, "b" amalgam filling, "d" edges failing from bite 
 stress, "c" recurrent caries; time in the mouth, nine years. 
 
 Q — View of the mesio-buccal angle bicuspid of a well-appearing silicate, six months in the mouth; 
 "a" enamel, "b" silicate filling. Note the open joint at "c." 
 
 his work may stand, of the vulnerable areas in cavity preparation, and as to which 
 type of joint he may use, porcelain and butt-joints for appearance when sheltered, 
 or a shelter can be made by inssetting in lap-joint gold inlays, which are always 
 preferable for accuracy and durability. 
 
 Finally, the future of the method of inlaying fillings in teeth will be dark indeed, 
 and this, the greatest boon of our times to both patient and operator, will be cast 
 aside as "weighed and found wanting," if we, as a profession, are satisfied with 
 present results. As seen in the light of these investigations the field is only just 
 invaded. It will not do to accept the present cavo-surface union of porcelain inlays 
 with the smug statement, "That joints will wash out any way, so what's the use?" 
 any more than it will serve to be comfortably pleased with our lap-joints in gold 
 inlays. We are convinced that both butt and lap-joints by suitable technique must 
 be made the equal of those found in the finest foil operations. It is going to demand 
 some of the finest science, art and skill that our profession has ever displayed to do 
 
THE CEMENT LINE IN I NLA YS 57 
 
 this thing, and we feel assured that in time the skill will be displayed, the science 
 
 applied, the art demanded put to practice, for never 3^et have we, as a profession, 
 
 failed, when convinced of the need, in the accomplishment ofttimes of the seemingly 
 
 impossible. 
 
 DISCUSSION 
 
 W. T. Reeves, Chicago, 111.: I am thoroughly in accord with all of the subject matter as Dr. 
 Grieves has presented it. I believe that you will find that when the paper appears in print and you have 
 had a chance to study it and to go over it not only once but several times, you will get great benefit 
 from it. 
 
 Now, I think that Dr. Grieves has summed up his conclusions that the filling that depends upon a 
 cemented joint has proven far superior to the contact filling, or the gold or amalgam filling as it usually 
 has been put in. As he said in that paper, the amalgam filling that has a cement lining is far superior 
 to the filling that has no cement under it. His conclusion came to the point that the minimum joint, 
 and the minimum amount of cement under the filling, gives the highest degree of result. He also 
 spoke about inlay operators differing, as to those who have a fit of the cavity throughout and those 
 who have only a fit of the cavity at the margin and depend upon a bulk of cement in the interior of the 
 cavity. He divides the subject as between butt joints and lap joints, and shows how it is possible to 
 obtain lap joints with a gold inlay. It is true it is only possible to obtain lap joints with a gold inlay 
 in the way that he has outlined, through cavity preparation. It is also true that in all butt joint 
 operations, you are limited as to your ability to set that inlay to its place. 
 
 We will take the cavity preparation that you have been making for gold inlays — and I take it 
 there are a greater percentage of the audience who use gold inlays than who use porcelain inlays. I 
 believe that in all that I have seen and heard on the subject, that you are following in your cavity 
 preparation a cavity form very similar to that advocated for gold foil fillings, that credited to Dr. Con- 
 zant, in which Dr. Grieves says is his ideal cavity preparation. I differ very decidedly from that cavity 
 preparation. You have followed that cavity preparation through your teachings and training in the 
 association of gold foil fillings in which you have had to have a retentive form of cavity and interlocking 
 form of filling, and you are following out that belief that it is mechanics that also governs to a large 
 e.xtent the retention of inlays in your cavity. I am still preaching that it is not mechanics in any sense 
 whatever. You may have a mechanical form of cavity that will hold that filling in, before any medium 
 is used to hold it in the cavity. It will not dislodge, but after the filling has been set mechanics does 
 not enter into play until the cement joint is broken — the cement joint breaks all over the cavity in one 
 instant. Consequently your mechanical fit will not enter into play. The greater area of surface you 
 have, the greater degree of adaptation to that surface, and consequently the greater amount of retention, 
 the greater pounds' pressure resistance there will be to its dislodgment. I do not wish to carry the 
 discussion away from the paper whatever, and I think the deductions of the paper bring us to the 
 point that the minimum amount of crevice, or joint, gives us the greatest amount of security. That 
 is, there can be less washout through mechanical force, if the cement does not wash out, and I believe 
 it is a well established clinical fact that the cement in a well fitted inlay will not wash out but half the 
 diameter of the crevice. Now, our object should be to obtain a fit of cavity throughout, as well as at the 
 margins, as great as you have obtained in your cast gold inlays. 
 
 The next point is, have no butt joints at any portion of the cavity. You well know that we cannot 
 take a flat surface of cavity and force the cement out to allow you to close that to the greatest degree 
 possible. If your cavity preparation will take more of what might be termed a wedge shape you then 
 may be able to set it with a minimum amount of cement. If I had a diagram (I wish I had known just 
 what the illustrations had been, I would have made a diagram to illustrate what I want to give you as 
 my form of a lap joint in a porcelain inlay, because I use that almost exclusively). I ha\e a small 
 model here that I use in teaching. It has been in use for a dozen of years, but I am afraid it is too 
 small for you to see. If the filling enters on the wedge principle, in doing so >ou are able to force your 
 inlay into the cavity and secure the minimum of joint. You will see that there is at no place anything 
 of the nature of a butt joint. 
 
 I have seen a number of times in print and heard a number of times, and Dr Grieves has spoken 
 to you tonight in regard to porcelain inlay men speaking of the washout of the cement in their joint as 
 advantageous to their filling, and that it helps in the making of the porcelain to match the tooth. I do 
 not know as I can in any way illustrate just what I would like to show you. If there is a portion that 
 would be a butt joint, and if filled with cement, the shadow would be cast directly into the inlay, but 
 if you prepared that so there is no butt joint, you will see that your shadow is cast downwards and 
 backwards, so that the shadow of the cement passes out through the inlay below the median line and it 
 does not cast a shadow into your porcelain. 
 
 Another point is the conditions of the mouth that Dr. Grieves speaks of in connection with erosion 
 
58 PRACTICAL MANUAL OF DENTAL CASTING 
 
 those conditions where porcelains look well but are soon dislodged because of the loosening of the 
 cement. That is very true, but in the same mouths gold foil fillings fail as quickly. I have found that 
 in that class of cases, it I extend the cavity considerably beyond the area that has been affected by the 
 erosion, then the acid that is precipitated will be dissipated by the saliva before it reaches the margin, 
 and those cases that formerly were soon dislodged I have had no difficulty about their remaining in 
 the cavity. 
 
 ■ As I said at the start, I think the great value of Dr. Grieves' paper will come to you when you are 
 able to read it. I hope it will convince you that the inlay principle of filling teeth really is the correct 
 principle. In a great majority of cases it will preserve more teeth than any other method that we 
 have used. The time is late, and I thank you very much for your attention. 
 
 S. F. GiLMORE, Indianapolis: The wisest man that ever lived said: "As iron sharpeneth iron, so 
 doth the countenance of man his friend." And I want to leave it to you if your minds have not been 
 sharpened by the countenance of Dr. Grieves, and by his paper, what he has said and what he has 
 illustrated. As I listened to his paper the quoted proverb came into my mind — "As iron sharpeneth 
 iron, so doth the countenance of man his friend." 
 
 1 have longed for some light on this very subject that has been so wel' presented, and now 1 can say 
 that I have the light that I sought. There is one question that forces itself upon the mind of every 
 operator as he is giving the final and finishing touches to a filling of whatever character it may be, 
 perhaps a beautiful gold inlay. It is a question that he asks himself, and the query is, "How long will 
 this filling preserve this tooth; how long will it last?" and echo answers, "How long?" He says he 
 thinks it will last for years, but as a matter of fact he doesn't know. The wish may be father to the 
 thought. 
 
 I feel especially honored at being appointed as one to open the discussion of this paper. To discuss 
 a paper from the pen of Dr. Grieves of Baltimore is a thing that I am utterly incapable of doing, but 
 then, there is nothing to discuss; it is all to commend. The man who discusses usually feels called upon 
 to differ with the essayist in some particular. In this case, to controvert is out of the question. It 
 would be like essaying to differ with a man who said that two and two are four; there is no ground for 
 argument. You know there are so many men who make deductions, that have their origin in fancy; 
 they fancy they will exploit that fancy and fancy that you will believe it. And while I concede the fact 
 that Dr. Grieves' deductions do not have their origin in fancy, but rather are the result of careful, 
 intelligent, painstaking, scientific research and observation, yet I must have a word with Dr. Grieves 
 on one particular point: on the matter of giving preference to a cemented joint in what is termed the 
 vulnerable chemical area, over one of perfect contact of metal to tooth. 
 
 Now, this perfect contact of metal to tooth may be had by a properly manipulated high-grade 
 amalgam, thoroughly burnished and perfectly adapted to the cervical wall of a cavity that is so situated 
 as to be practically inaccessible to direct vision, or after a filling is inserted, inaccessible to even reflected 
 vision. The class of cavities that I refer to are those deep ones on the disto-proximal surfaces of molars, 
 superior or inferior; those dark corners where you cannot see what you are doing, or what you have done 
 after you have done it. The insertion of an inlay in such a locality is always accompanied by a feeling 
 of doubt on the part of the operator as to whether or not he has secured good contact at the cervical 
 wall, as to whether or not there is proper alignment between metal and tooth surface. If his exploring 
 point conveys the information that the gold overhangs, he finds it impossible to burnish to any ad- 
 vantage through the embrasures. His patient will not submit to it; all efforts to do so result in ir- 
 reparable damage to the soft and sensitive tissue. If he has accidentally produced an inlay entirely 
 free from overhang, if he has a perfect alignment between metal and tooth, what assurance has he that 
 the shrinkage of his casting has not resulted in too fat a joint to be dependable, especially in a butt 
 joint? 
 
 As our essayist says, "A greater number of failures may be noted at this point, the vulnerable 
 chemical area, than at any other, for the evident reason that the correct setting and finishing of the lap 
 under the gingivus, without damage thereto, or overflange, causing retention, is one of the most difficult 
 procedures in operative dentistry, and needs much bellermenl." 
 
 In my experience with inlays of the malnx type, I have discovered that the weak point is the 
 cervical wall, principally in all cavities of the class referred to; that perfect adaptation and surface 
 alignment is out of the question; and that without these important factors, recurrent caries at the gin- 
 gival margin is the result in most cases. As the result of my experience along this line, I have adopted 
 and practice what I have proven in my own experience, at least, to be a satisfactory solution of this 
 problem: All cavities having a gingival wall or border that are not accessible to reflected vision, or 
 satisfactory instrumentation, after the filling is seated, should, as a part of their preparation for an 
 inlay, have at least a layer of amalgam, one or more millimeters in thickness, vigorously and thoroughly 
 burnished to contact with said wal). A careful adaptation of the matrix will make this method an easy 
 matter, because the modern matrix properly adapted automatically produces contact and alignment. 
 All that is necessary is for you to apply the force. 
 
THE CEMENT LINE IN I NLA YS 59 
 
 This method carries with it the sustaining argument that the element of guess work is largely 
 eliminated, so far as adaptation is concerned. The field of operation is brought up to a point where 
 the operator can see what he is doing. What a comfort it would be if we could see exactly what we are 
 doing in a large number of the operations we perform in the human mouth. What a comfort it would 
 be if the element of guess work could be eliminated, when we are preparing for filling a canal that is 
 filled with deleterious matter. If we could only see when we have the last bit of septic matter out of 
 that canal, and when we have properly sterilized it for its filling; if we could see our gutta percha point 
 carried just to the right spot. Speaking about comfort, I am tempted to tell a story: 
 
 An Irishman and a Dutchman were working side by side on a public highway, and as they worked 
 they talked. Among the various things they talked about was the subject of what was the most 
 delicious article of diet. The Irishman thought nothing could excel the Irish potato. The German said 
 there was nothing that could equal Limburger cheese. The Irishman had never heard of Limburger 
 cheese and it was new to him. The German said to him, "I will convince you; I will have my grocer 
 send you up ten pounds of Limburger cheese and I want you to feel that you are putting your feet under 
 a table that is groaning with the best thing it is the privilege of man to consume." When the Irishman 
 went home that evening he saw Martha standing as he approached the house, with a cloud on her face, 
 and she said to him, "Mike, you better not come in; well — maybe you better come in." Mike said, 
 "Did a man bring something here?" and Martha answered, "Yes; the grocer brought something up 
 and it is spoiled, whatever it is, and the odor of it in the house is awful. I wish you would come in." 
 Mike agreed with his wife that whatever was sent was a mistake and was badly spoiled. His Irish 
 neighbor came in for an evening call, and he sat there and talked about one thing and another. Finally 
 his curiosity got the better of him and he said, " Mike, have you had a death in the family?" Mike was 
 loath to acknowledge the cause of the trouble, so he thought the best way out of it was to say yes. His 
 friend said, "Mike, was it one of the family?" and Mike said "Yes." "I hope it wasn't one of the 
 children," and Mike said, "No, it was my mother-in-law." His friend said, "Well. Mike, it is an awful 
 thing to lose a mother-in-law, but you have one thing to comfort you. When you come to bur>- her you 
 will not be afraid she is in a trance — she is sure enough dead." 
 
 When a man puts in a gold inlay he satisfies himself in every way that it is a beautiful inlay, and 
 his patient compliments him. In the course of time his patient comes back and takes his seat in the 
 operating chair, and says: "You know that beautiful inlay you put in," and you pass your instrument 
 in there and it goes into a hole, and you find debris and one thing and another. You are satisfied at 
 once that whatever was in there is not in a trance, anyway. 
 
 I submit that the experience of every operator present and the history of every amalgam filling 
 that has been carefully and conscientiously planted against the cervical wall of a cavity, would, if such 
 history were available, bear me out in the statement that a smaller percentage of recurring caries may 
 be found in what our esteemed essayist has designated as "the vulnerable chemical area," where 
 amalgam has been employed, than that of any other filling material. If you use this method you 
 need not give yourself much concern as to whether or not the oral secretions remain normal or change 
 to Hyperacid or Hypoacid conditions. One of the old dependable wheel horses of the dental profession 
 can still, as in the past, be depended upon. 
 
 Now, will you tell me of any good and valid reason why you should not employ a thin film of 
 quick-setting amalgam under an inlay in the territorj' referred to, and then comfort yourself with the 
 thought that your beautiful inlay, with its perfect lap joints, lingually, buccally and occlusally, will 
 stand as a monument to your skill and not eventually topple over because it was undermined? 
 
 Alexander Jameson. Indianapolis, Ind.: When I received a copy of this paper by Dr. Grieves I 
 had the feeling that the gentleman who selected me to discuss the same did not show as fine perception 
 or as good judgment as he should have shown. I think that it requires to discuss this paper somewhat 
 of a mechanic, a good deal of an artist, a great deal of a bacteriologist, and a man who is more or less 
 a past master in several of the arts that the average dentist has not time to look into. In other words, 
 it presupposes more ability than I have. 
 
 However, there are some points that I particularly want information on. It is no discussion of a 
 paper to get up and say that it is well read and well presented. We all know that, and this paper shows 
 a wonderful amount of investigation and research. I want to cut my remarks short and get down to 
 the gist of the matter and find out, for instance, where this fits. 
 
 There is a lesson to be learned in everything of this kind, from every effort that is an honest effort, 
 and this one undoubtedly is, and we want to draw our conclusions where this fits into our everj'day 
 practice and life. 
 
 We are assured that the lap joint inlay is fll-en better than we thought it was. However, I want to 
 get back of a few things. I have never had much doubt of one thing, and I hope you won't hit me with 
 a brick when I say it. I believe the average man doing the average work can do a better piece of work 
 with an inlay than he can with a gold filling. That does not prove anything, however. 
 
60 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Dr. Grieves has shown by a great many figures and beautiful illustrations the cement line under 
 these fillings. He has drawn a conclusion himself that the cemented filling is better than the contact 
 filling. On the other hand, to go back and be scientific about it, he has not given us the history of those 
 pictures. I doubt whether there are any of those cemented fillings that are as old as some of the con- 
 tact fillings that Dr. Grieves has not had a chance to see. As a clinical proposition I have got to be 
 shown that the right kind of a contact filling isn't about right. If it is not the right kind it may fall 
 into the hands of Dr. Grieves and be dissected and thrown upon the screen. He hasn't told us how old 
 they were, etc. I think they both ought to be put in under the same conditions, live the same life and 
 then be subjected to the same analysis in order to give us something that is scientific. I do not believe 
 the doctor said where these fillings were from, how long they had been in, who put them in, nor anything 
 about the conditions. You can take a contact filling that has been doing nice work in one mouth for 
 four or five years, and it will fail in another mouth. The doctor himself has given us a classification 
 that shows that any filling fails in certain mouths and others do well. Now, those classifications, ac- 
 cording to his own statement, might obtain in a case of this kind. A contact filling may have been in 
 one of these mouths that was not the best place for it, or a filling of any kind. The cemented filling 
 may have been in one where there was all the advantage. Until we can get data upon these things that 
 are absolutely conclusive, I would not feel that his conclusions were absolutely to be relied upon. I 
 think he is along the right track. His work has shown us some wonderful results. 
 
 I differ with the doctor in one or two little things, but I do not know that it makes any difference. 
 The doctor says that for gold inlays there is nothing but pure gold. I think that is a debatable proposi- 
 tion. The average gold filling is harder than the twenty- or twenty-two-karat cast inlay. We have 
 seen many contact fillings that have the characteristic floor, and you have a cemented filling that is 
 softer than that is. The only possible advantage that I know of for gold filling would be that it would 
 be just a little harder than the twenty- or twenty-two-karat gold. Time will tell and tell what is the 
 best material. 
 
 Now, Dr Grieves' ideas and theories presuppose another thing. These classifications were made. 
 At the same time my idea is that those classifications more or less come up a good deal like the old 
 question of temperament. We have to be an observer to tell anything about temperament, unless we 
 make quite a study of it. We say that so and so had black hair, etc., and a cenain temperament 
 predominates. 
 
 Now, to make these classifications effective there should be in every community of dentists some 
 man or men with a laboratory where we could send our patients and have_ certain tests made. We know 
 in a general way that so and so is so. We ought to be able to send our patients to the laboratory 
 and have certain tests made to classify them. After all, it comes down to the proposition, if he belongs 
 to this particular class where the lap joint fillings will preserve his teeth, why not make them all lap 
 joint? Why not be hunting for the worst kind of a case and in doing that make every filling the very 
 best we can? 
 
 In the discussion last night there were some amusing points brought out. Dr. Gilmore makes a 
 statement that amalgam as a base was the only thing for a gold inlay. Dr. Grieves stated that he al- 
 ways puts an amalgam filling in with cement. Why not get all these things together and have them all 
 right, have them all there? I think it would be a great idea to work all these things in and have a 
 proposition that would be worth while. 
 
 The fact remains that I have seen as a clinical proposition contact fillings that are in the mouth, 
 that have been there as many years as some of us are old, that are doing the work. Now, they may be 
 in those mouths that are more or less immune, but some of them are not. After all, it comes down to 
 that proposition. The well made contact filling — well, you have to show me that it isn't all right. 
 Still I am delighted to know that the cemented inlay is going to have such a good send-off. 
 
 Now, the answer to all this is just one thing, and the doctor suggested the answer in his paper last 
 night, and it leads up to another trend of circumstances. Let us have cement do the work. If we go 
 to work to get it we will get it. Let us get a cement that is acid and alkaU proof and that will do the 
 work. That brings up the story of the man who said he wished he had three hundred dollars. Some- 
 one said to him, "If you had three hundred dollars what would you do with it?" He said, "Well, if I 
 had three hundred dollars I would buy a sawmill." His interrogator remarked that if he had three 
 hundred dollars he wouldn't need a sawmill. If we had a cement that would do the work why would 
 we want a gold inlay? We have to do the best we can with what we have. This cement problem, 
 after all, is the answer to the whole proposition, in my mind. 
 
 Alexander White, Indianapolis, Ind.: I would like to bring out one point that Dr. Grieves 
 mentioned last night, about the use of pure gold for all inlays. I believe he made the statement that 
 he used pure gold for all gold inlays, and I would like to ask if there are not some indications for using 
 twenty-two karat gold. I am asking for information, as some of our best practitioners use twentj'-two 
 (carat gold almost exclusively, while others claim they use nothing but pure gold. Which is righ^? 
 
THE CEMENT LINE IN I NLA YS 61 
 
 I use pure gold almost exclusively, but use twenty-two karat gold in some cases, as for example, the use 
 of inlays for bridge abutments. 
 
 Another point made by Dr. Grieves' discussion was the model a great many of you saw. I would 
 like to ask about the gingival of that cavity preparation It is against the principles taught by Dr. 
 Black and a great many others to make an upward slope of the gingival wall. They teach us to make a 
 flat gingival base bevel the outer margin down, while he has the entire margin to slope upward. Know- 
 ing the anatomy of the tooth structure, I believe a cavity prepared in this way will leave short enamel 
 rods to soon drop out. and we will have recurrence of decay at the gingival as shown by Dr. Grieves 
 with the lantern slides. 
 
 Closing by C. J. Grieves, Baltimore. Md.: First I want to take up the point just made in Dr. 
 Reeves' discussion of my paper. I would like very much to have that cast, and I want particularly 
 to express my appreciation of what has been said in regard to that cavity preparation. 
 
 Dr. Reeves said that he made lap joints in porcelain. I think the general opinion is that the lap 
 joint is where the cavo-surface enamel is lapped by the filling edge. That is not the result only of theory, 
 that is the result of actual practice, as shown by Dr. Black and his confreres, and every operator knows 
 that there must be no short rods left. The preparation made by Dr. Reeves was just the reverse of this 
 rule. He cut under his enamel wall and left a lot of short rods which overlapped his butt joint. I 
 noticed in the cast he presented that when it came to the incisal angle, his line was just the same as done 
 by any other operator, his cavo-surface angle at 90 degrees, inasmuch as there was no cover then to 
 the cavo-surface cement and it would be pumped out very quickly. Labially and lingually these short 
 enamel rods would soon chip oflf; I doubt very much if they would stand. 
 
 I admire Dr. Reeves as an operator, but I have to say that much about that form of cavity prepa- 
 ration, inasmuch as it is just the reverse of what is practiced by every operator in all types of filling. 
 That does not make it wrong; it may be right but I doubt it. 
 
 As to the other point, the mechanical retention, here again I will differ sharply with Dr. Reeves. 
 He said that mechanical retention amounted to little or nothing, that the cement held the filling in the 
 tooth. The cement is a retainer, of course, or we would not use it, but I have always thought that 
 cement came into the joint to close that joint, simply as some adhesive media, to exclude mouth juices 
 as between the filling and the cavo-surface enamel. If you are depending upon cement to hold your 
 filling, why make any retention at all? The fact of the matter is that the mechanical retention I believe 
 time will prove, after all, is the thing; the filling is retained by mechanical retention and that in turn 
 retains the cement, and the filling must have some seat in the cavity that it may find its place. 
 
 There is a long line which we have not the time to go into. I think it has been shown by every- 
 body who has studied cement that all cements leak. I showed some cement on the screen last night, 
 stained one-third the depth of the walls. If they don't leak along the joints their body substance acts 
 as a filter, filtering the saliva of the germs in the mouth and by this filtering process preventing decay 
 of enamel. If you will experiment you will find the waterosin will go down under the cavo wall in 
 cement fillings. So I am not willing to depend entirely upon cement as a retainer. I want mechanical 
 retention. I only wish we could figure out some way to make a safe lap joint in porcelain. If you lap 
 your enamel the enamel chips off and so does the porcelain when it laps. 
 
 The ne.xt point, one brought out by Dr. Gilmore, is one upon which I would like to spend some time, 
 that about amalgam. I shall feel repaid for my trip here if I have impressed you with one thing of 
 value: I would like to leave with you the fact that the cemented-in filling of either crystal gold or 
 amalgam is the greatest thing in dental practice today. I have been practicing this method for eight 
 or ten years, the method of working quick-setting amalgam in slow-setting cement in large cavities in 
 the back of the mouth, and with the oiled matrix working in and completing your contour in amalgam 
 you have a filling which is indeed "cemented in" with a line of cement much finer than could be made 
 by the most expert inlay operator. If you watch those teeth for a year or two you will find there has 
 been no discoloration of the surrounding tooth structure. All that I have said of the cemented-in 
 amalgam I can more than accent for small fillings made of crystal golds in cement. 
 
 Personally I believe there is not an amalgam on the market today which does not materially move 
 some time, or flow under stress, so that I would not trust Dr. Gilmore's proposition of laying amalgam 
 bare at the gingival seat, neither do I like the association with gold in the mouth fluids. I firmly be- 
 lieve that the reason amalgam fillings save teeth is from the fact that they leak saliva. One of the 
 biggest gynecologists that I know of is placing a strip of silver foil after large operations directly in 
 contact with the exudating tissue, the silver salts take care of the wound, which becomes black and 
 finally disappears. So I figure that the old silver amalgam filling leaks saliva, and the salts of the 
 saliva go down into the dentine and make the tooth black, and unless the crevice be a large one 'you 
 do not have recurring decay. Nine-tenths of the average amalgam fillings I believe save teeth after 
 that fashion. 
 
62 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Now, in regard to Dr. Jameson's remarks, I did not want him to say what he did about the mouth 
 classification. I do not believe that it is at all as useless as the classification of temperament. I want 
 to see every man get to be an expert in mouth diagnosis. I believe it can be done. That little effort 
 of mine was the result of the work of other men simply being compiled, and I believe we will get to the 
 state where we can look into the mouth and say what has happened to that mouth. You are doing it 
 subconsciously every day. You are governed by what you are observing of the enamel surfaces and 
 how the work of other men has stood. You glance around that mouth and make up your mind what 
 you are going to do in this particular instance by what has occurred in the past. Every man cannot be 
 an analyst, as the doctor says, of saliva, and I question how much it would help him if he could, but we 
 can have some more definite idea, which I believe can be made practically this classification. 
 
 Just as an instance — I have been applying this method for about two years in my practice. T 
 would not put a butt joint in an erosion mouth if I could help it, because I know that the acid salts 
 would play "hob" with my cement. That is a very broad statement. That means your patients have 
 to have lap joint or gold fillings in their teeth. We know that porcelain butt joints are going to fail 
 in a little while, and I would trust a lap joint of all things under these conditions, because I think the 
 gold can beworked down to such a shape as will stand. Again, you instinctively follow the rule of the hypo- 
 acid classification, where we have everything fail in examining children. The hypoacid period is the 
 period largely of childhood. These little children use starches, have to have them. They use sugar; 
 it is the carbo-hydrate food period. The saliva itself reflects their body condition, being loaded with 
 glycogen. Under these conditions — I think you all know a hypoacid mouth — (and I believe some 
 change can be made in the diet without doing damage to the patient). You would not put porcelain 
 fillings in the mouth of such a child of the hypoacid mouth variety. I believe that these classifications 
 have a practical value every day. 
 
 If 5'ou keep those three figures in your mind and look through the mouth you will find that you are 
 applying that more or less and get more skilful in it as time goes along. 
 
 In regard to the contact operation, I approach this subject with considerable temerity. Before 
 I studied the cement line I spent a good deal of time looking at every filling I could. My method was 
 to slip a rubber dam over every filling and put formaldehyde on the surface to harden the films, then 
 stain these teeth after extracting and split them open that I might get caval conditions as they actually 
 were. 
 
 I made a statement in a former paper, of which some of you have copies, that personally I believe 
 that there has never been a contact operation made but what leaked saliva at some point. In other 
 words, that saliva flows through the joints and under all fillings. That your contact operation suc- 
 ceeds, regardless of the fact that it leaks saliva, we all know, because we have all taken out hundreds 
 of gold fillings that have been leaking, and you have seen them in scores the best of contact operations. 
 That these fillings did not fail is due undoubtedly, I believe, first to the mouth conditions. They may 
 have been immune mouths. But principally I believe that the protective film I described has blocked 
 those joints, as we know it does block the cement joint, preventing the ingress of bacteria, or isolating 
 the culture from its habitat. This is what you find in a leaking contact operation which has leaked 
 and yet is not carious. 
 
 I also maintain that the well made inlay joint does not leak except possibly a little, the cement 
 acting as a filter, which was clearly shown by the stainfng in the caval cement in my slides. 
 
 I tack my faith to pure gold, while I recognize the truth of what Dr. Gilmore has said. For the 
 same reason that the contact operator uses his pure gold, I claim that I can make a better joint. What 
 you are after is the cavo-surface contact between your gold lap and enamel, the lap can always be 
 better burnished down. I think the proof of this is in the burnished inlay that we used to make of pure 
 gold matrix and solders. I made very few joints which were as good by the old burnishing method as 
 by the new gold; casting the gold solders or twenty-two karat plate always made a ragged edge which 
 I could not handle, and in the effort to polish it up I often opened up a very much larger lap joint 
 than I had planned to have. 
 
 I want to thank all the gentlemen for their courtesy and to assure them that the field is just merely 
 opened. I have only touched one little corner of it. I think it is a field primarily of mouth classi- 
 fication which we dentists simply must know. We must know our environment, we must know it 
 just as much as the physician knows his environment. We can not get on by putting in three or four 
 types of filling just because it is the thing to do, but we must study our mouth environment, and per- 
 sonally I know my results will be better. I hope this paper will be torn to pieces if it is wrong, because 
 I want it to be right. 
 
SOME PRACTICAL POINTS ON INLAYS 
 
 By L. E. Custer, A.M., D.D.S., Dayton, Ohio. 
 
 CONDITIONS NECESSARY FOR UNIFORM CASTING 
 
 First thing necessary is an investment — a material which will neither shrink 
 nor expand and which will withstand a high heat. For this purpose I have used a 
 material composed of plaster of paris, one part, and highly calcined fire-clay, four 
 parts. This possesses two advantages over plaster and silex. The fire-clay having 
 been burned at a much higher heat than that used in casting, does not shrink during 
 the latter act. It, moreover, possesses a valuable feature over silex. If silex is 
 examined under a microscope it will be found to present a smooth glass-like fracture, 
 whereas the fire-clay particles present a rough and somewhat porous surface. The 
 advantage is obvious. The plaster ingredient in the mixture should always be as 
 little as possible and a mix of fire-clay and plaster will contain less plaster for a given 
 strength than a like mix of plaster and silex. A cubic inch of the above when brought 
 to a red heat will shrink scarcely a thousandth of an inch, therefore the shrinkage of 
 the average inlay mold would only be about one-fifth cf that — too little to worry 
 about. 
 
 The second factor is the condition of the mold at the time of casting. It should 
 be thoroughly dried and raised to practically the same heat each time before casting. 
 If the investment has not been thoroughly dried out steam will form at the moment 
 of casting and prevent perfect filling of the mold. It is important to heat the in- 
 vestment quite hot so that any decomposition cf the plaster will have taken place. 
 If the gold is cast into an investment which may have been dried out, but which has 
 not been heated up quite well, a slight decomposition of the plaster is produced at 
 the moment of casting and an imperfectly filled mold is the result. An incidental 
 advantage is also found in casting in a hot mold — the gold need not be heated so hot 
 as where it is cast in a cold mold. 
 
 It is important to always heat the gold to as near the same degree as possible. 
 Theoretically, it should be fiuid till every recess of the mold is filled, and >et not so 
 hot that it remains longer in a fluid state. Unless the gold quicklj^ solidifies after 
 being cast, although the case may have been dried and well heated, the plaster will 
 liberate gas under melted gold and an imperfect filling will result. 
 
 The gold should be cast under the same pressure each time. There are prac- 
 tically only two methods of casting — compressed air and centrifugal force. When 
 compressed air is used (steam and gas come under this head) it is important to always 
 have a good surplus of gold so that the edges may be sealed by the weight of the 
 fluid gold, otherwise air will leak under the gold and ruin the casting. The surplus 
 gold in this case, especially where the basin is quite saucer-shaped, does not affect 
 the force with which gold casts as much as where centrifugal force is used. There is 
 no reason, therefore, unless one is hampered by a poor heat, why a good surplus of 
 gold should not be used when casting under compressed air. Where centrifugal 
 force is employed as the casting agent, the conditions are different and here it is 
 especially important to use about the same amount cf gold each time, allowing only 
 for the difference in the size of the fillings. Having once ascertained what amount of 
 
64 PRACTICAL MANUAL OF DENTAL CASTING 
 
 surjilus gold insures a perfect casting under a given centrifugal force those conditi(jns 
 should be repeated as nearly as possible. The mold is easily distorted by too great 
 a head of metal or by too high centrifugal speed. 
 
 APPROXIMAL CONTACT 
 
 No feature is so important in approximal fillings as the contact. Heretofore, 
 this has been difificult to secure in malleted fillings, but with the cast inlay it is quite 
 easy, and if the cast filling had no other points of advantage this would be one to 
 recommend it. The wax filling, unless there has been ample room for its finishing, 
 will show a small facet where it touched the neighboring tooth. This should be 
 rounded out with wax, or as I prefer, after casting, to flow a small bit of 22 karat gold 
 upon the facet, thus contouring it out with hard gold at the point of contact. 
 
 DO NOT DEPEND TOO MUCH UPON THE ADHESIVE PROPERTY OF THE CEMENT TO RETAIN 
 
 THE FILLING 
 
 There has always been too much faith placed upon the retaining property of 
 the cement. In order that the operation may be facilitated the walls in many 
 cavities that might be prepared almost parallel are quite funnel-shaped in principle. 
 This should not be. Where thin walls surround the cavity it should be kept in mind 
 that these do not serve well to retain the filling and unless these walls are protected 
 upon the masticating edge they will soon spring enough to break up the cemental 
 attachment. We are prone to gauge the retentive property of a cavity by its mside 
 form. We seldom take into consideration the thickness of the cavity wall. The 
 loss of many fillings is due to placing too much dependence upon frail walls. 
 
 CEMENTING 
 
 If you examine a metal inlay that has come out, as a rule it will be found that 
 the cement has broken its attachment with the tooth substance and is still adhering 
 to the gold. This was probably due to imperfect drying of the cavity at the time of 
 setting. The cavity walls should be thoroughly dried to insure adhesion of the cement 
 thereto. This adhesion can be very much increased by wiping the cavity out with 
 a little of the cement liquid and drying just before setting. This seems to pre- 
 pare the surface for a stronger adhesion of the cement. We have seen the cement 
 cling to the instrument rather than to the cavity walls at times. This is due to faulty 
 drying out of the cavity. If it is difficult to secure the most perfect dryness it is all 
 the more important to use the liquid method before setting. 
 
 RESTORATION OF FRACTURED ROOT BY THE CASTING METHOD 
 
 By J. Maurice Crosby, D.D.S., Bradford, Pa. 
 
 Remove the fractured portion of the root, attach a handle to the outside with 
 wax, or better, drill and tap labial surface of fractured portion and attach a piece of 
 German silver anchor-screw wire. This forms a very secure and convenient handle. 
 Oil the inner surface of the fracture. Make a stiff mix of plaster into which press 
 the fractured part of root, inner side downward, to get an impression. When set 
 hard remove carefully. Immerse the impression in water and fill with wax, restore 
 contour of labial surface. Remove and cast. Adapt to the root in the mouth with 
 the crown post in proper position. Wax the inlay to post while in the mouth. Re- 
 move, invest and solder post to inlay. Replace in mouth and finish with band and 
 cap as for Richmond crown, or a half band fitting the lingual surface may be made of 
 wax in the mouth; remove with inlay, post, and cast to same. 
 
EXPERIENCE AND EXPERIMENTS IN DENTAL CASTING 
 
 By J. R. Osborne, D.D.S., Shelby, N. C. 
 
 I ha\e chosen a subject that calls for considerable employment of the first 
 personal pronoun, and my apology for so doing is, I believe I can present some ideas 
 I have on this subject more intelligibly and more profitably by a recital of my own 
 failures and my own successes. 
 
 I found this work one oi difticulties. There are a great many things about it 
 tiiat are fairh- understood now tliat were ncjt known when 1 began it, eighteen 
 months ago. 
 
 Forcing molten gold into a previous!}- prepared mold is about all it takes to 
 define this process, but it implies the working of some materials not so tractable, 
 and the employment of a technic not so "easy as falling off n log." 
 
 I agree with Dr. Taggart that "it is not a lazy man's work," but not in his 
 statement that it will "make a poor dentist a better one," any further than to say, 
 it might and it might not. The dentist who cannot make a good cement or a good 
 amalgam filling, for instance, would not be the one to succeed in the casting business. 
 
 It is a work, too, that will not admit of a neglect of detail. Several conditions 
 must be met, many kinds of work performed, the neglect~of any one of which leads 
 to failure. And there are no partial failures in this work. All failures of any kind 
 and to any extent, are failures. Nor has it reached the stage of perfection. When 
 some clever fellow tells us how to overcome the inHuence melted metal has on the 
 walls of our mold cavities, then it will be about time for us to make proclamation 
 that we are at or very near the goal. 
 
 Those of us who have worked incessantly and earnestly ha\e o\'ercome the 
 other difficulties that gave us all so much trouble when we first embarked in this 
 work. Let us compare notes and tell of troubles and see how nearly we are together 
 at this time. When I began, which was just as soon as I could get a machine from 
 the Taggart people after the announcement of the cast inlay was made in February. 
 1907, I found among other troubles waiting for me, something like this: 
 
 An imperfect machine. 
 
 An investing material that brought me trouble. 
 
 A model material that is not an ideal one for the work. 
 
 A large solid cuji that caused me to endure hardness. 
 
 First, as to the machine, I do not wish to say that the Taggart machine is im- 
 perfect for the dentist who has city gas to mix with nitrous oxide gas that accom- 
 panies the. outfit, but it was certainly imperfect for me, not ha\'ing this gas, and of 
 course I could not use the blow-pipe side at all. 
 
 I calculate a poor wretch in Hades with his claws cut off, and a poor dentist in 
 a town without illuminating gas, and a Taggart machine are alike, at least in one 
 respect — poorl}' equipped for what is before them. But I had to cast with it anyway 
 ffor I had purchased it). In having to cast with it, I found out a principle that has 
 settled the casting machine question with me. In tr\ ing to break the joint between 
 the machine and the cup, using a wet in\estment, I made a good cast with not a 
 pound of pressure, so far as pressure from the gas is concerned. My mind rex'erted 
 
66 PRACTICAL MANUAL OF DENTAL CASTING 
 
 to the time many years ago when I poured molten lead into a green cane. The 
 promptness with which the lead returned was something fierce, and left me with at 
 least two impressions, one on the inside and one on the outside of my head. But 
 laying all jokes aside, I am here to tell you that in my opinion that same force that 
 gave me the sore head is the one to drive hot gold into the mold prepared to receive 
 it. I say this after I have had experience with not only the Taggart machine, 
 but all the other ones of any prominence and a lot cf the toys thrown in. I had a 
 machinist here make me a machine after m}' own ideas. I wanted something positive 
 and quick and now I am on Easy street. 
 
 I have used all the investment materials on the market and have found them 
 unsatisfactory. A perfect one, so far as I know, remains to be worked out, unless Dr. 
 Price has it in his artificial stone. I hope he has it, as this one thing will be a stumb- 
 ling block until it is removed. The trouble is, it must be impervious to meet some 
 decided requirements and not impervious to the extent that it will not take care cf 
 
 Figs. 1, 2, 3, 4 and 6 
 
 the air contained in the mold previous to casting. This is but one complexity of 
 this complex part of the work. I thought I had it fixed in the taking of a perfect 
 impression and running a model of the tooth and cavity, and making a model of 
 oxyphosphate cement. This gave me some big advantages that I had to turn down. 
 Looked good to me that I did not have to remove the wax model from the cavity, 
 as troubles more than some folks think creep in just here, in the removal of the wax 
 from the cavity in the tooth in the mouth. 
 
 Then, again, the cement model comes out of the fire in better shape, with less 
 change, than any of the materials in the cup. This gives us a great advantage in 
 finishing the filling out of the mouth, an operation that the patient is not apt to find 
 any fault with. But the cement is too dense to allow the escape of the entrapped 
 air. I fought hard to sprue in a way that I could overcome this one fault, but 
 except for certain pieces, I have failed. For casting a shell, this is the ideal way — 
 using a cement model invested with the wax. 
 
 SEPARABLE CUP 
 
 I conceived early in the game that the large cup was all wrong, in that it is large 
 and that it is solid. Wrong because it takes too long for the investment to dry out. 
 Wrong because there is always a residue of wax enough to blacken the gold and often 
 there is enough to do a lot more damage than that. Wrong because wax is not in all 
 cases, in fact, in few cases, an ideal model material. I devised a cup and for the 
 last twelve months I have used it with great satisfaction. I use a small separable 
 cup and have changed the time necessary to dry out an investment from 40 to 60 
 minutes to 15 minutes. Two halves of an investment will dry out in less than 
 half the time required for a solid mass. 
 
 One of the beauties of this idea is, I can use a model material that has many 
 advantages over wax. 
 
EXPERIENCE AND EXPERIMENTS IN DENTAL CASTING 67 
 
 A knowledge of how to sprue is essential in using this cup if you wish to use as 
 hard a substance as cement for a model. I have often used amalgam but I find no 
 advantage in it over cement or modeling compound, except in certain cases. It 
 gives a clean mold and of course a clean cast, something very much desired. Seven 
 minutes to set, one minute to warm cup, separate and remove model, and seven more 
 minutes to dry out (using a properly constructed dr^'er) and I am ready to bet on 
 the result. 
 
 I neglected to saj^ under the head of investing material, what I use for that. 
 As I said, I have used all the leading materials and have experimented a whole lot, 
 but none has served me so well as the impression and Investment Compound put 
 up by the Consolidated people. I am not referring to the investment they put up 
 for gold casting. It may be better than any, but if it is I do not know it, not having 
 tried it. Returning to the cup matter, I will say that a reference to the cut will 
 help you to get an idea of the advantages this separable cup has over the solid one. 
 
 Fig. 1. The larger half of the cup on the crucible former with sprue and model 
 filling in position and ready for in\cstment. 
 
 Fig. 2. The smaller half of the cup which is not placed in position until No. 1 
 has been filled with the investment. 
 
 Fig. .3. The sprue, threaded at one end to screw into the crucible former in 
 order to sprue at a certain height to break investment at proper place. 
 
 Figs. 4 and 5. The cup after investing, setting, warming, separating and re- 
 moval of model. 
 
 SEPARATE BASE FOR A CAST GOLD INLAY 
 
 By F. R. Henshaw, D.D.S., Indianapolis, Ind. 
 
 This applies to those compound cavities in bicuspids and molars, where it is 
 extremely difiicult to prepare the cervical portion without extensive waste of the 
 labio-buccal and linguo-buccal margins. Prepare the proximal portion of the cavity 
 so that it will draw, regardless of the occlusal portion. Make wax model and cast 
 this portion of the filling. It is easy to see that you have obtained a perfect contact 
 at the cervix, which is the crucial point in any inlay. Set this portion of the inlay and 
 prepare the occlusal portion as for a simple case. Cast, and set the second portion 
 and the result will amply reward you for the additional labor. 
 
 RESTORING TEETH FOR CROWN AND BRIDGE WORK BY CASTING 
 
 By C. Jensen, D.D.S., Mt. Gilead, Ohio. 
 
 No doubt every dentist has a method of his own in restoring teeth for crown and 
 bridge work, but I think the most simple way is that of casting by the following 
 method : First, see that the roots are in a good healthy condition, then prepare canals 
 for pins, place pins in position, warm wax, build up and shape wax model so that you 
 can fit crown over same, cut down wax model so as to form a slight shoulder on 
 which crowns rest: this can be done after casting, if desired; withdraw pins with 
 wax model, invest and cast, using Acolitc; finish up cast as desired; make band 
 as for ordinary' gold crown, soldering piece of gold over end of band. Cement cast 
 in position, then place band over cast, place warm inlay wax on band, have patient 
 bite to obtain perfect occlusion, then carve up cusp, remove crown and cast cusp, 
 finish up crown and cement in place, and you will ha\e a tooth that will be ser\Hceable 
 in every way. 
 
68 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 AIR VENTS IN CAST WORK 
 
 By D. D. Smith, D.D.S., Sandusky, Ohio. 
 
 The first question asked when the cast inlay came into use was, "In mailing 
 the cast, where does the air get out?" 
 
 We know that the air dees not always get out. 
 
 My object is to show a few ways to overcome this trouble. .Some have been 
 using a sprue wire from the base of the investment and not allowing it to come 
 
 -WAX 
 
 ,-^.4-^.---— -ASBESTOS ROPE 
 
 n direct contact with the impression, but withdrawing it a little. In these cases the 
 gold is apt to blow or suck through and thereby make a failure. 
 
 If a little asbestos rope (about the size of an engine drill) be dipped into hot 
 paraffin and allowed to cool, it will be of great service in forming air vents in cast 
 work. Pour up as usual and while the investment is still soft insert the asbestos 
 rope. The wax will make the asbestos easier to handle and burns out when heated, 
 leaving a porous passage for the escapement of air and gases. 
 
 The asbestos may come in direct contact with the inlay wax. 
 
 METHOD OF OBTAINING A SHEET OF INLAY WAX SUITABLE FOR 
 USE AS A BASE PLATE 
 
 By Newton W. Hiatt, D.D.S., Marion, Ind. 
 
 The inlay wax is melted in small cup, so that the depth of wax is about three- 
 fourths {^i) of an inch. A small round vial is then filled with cold water and soaped 
 well on outside. The thickness of wax depends on the number of times the 
 vial is dipped into the wax. It should be dipped quickly each time. After accumu- 
 lating the required thickness, the wax on bottom of bottle should be trimmed ofif, 
 and a warm knife run through the wax the long way of the bottle, when the wax 
 will come off very easily. By warming this in warm water it may be adapted to 
 any shaped model, and removed and cast as any inlay or crown. The object of 
 the cast plate, which is particularly adapted to the lower partial plates, cast in full, 
 or with the use of the lingual bar, is to avoid the making of metal dies, which in 
 some cases is very difficult, and even when the metal dies arc ol)tained it is .sometimes 
 very hard lo swage, on account of the gold buckling. 'Hie cast plalc (ucrconies all 
 this, and can be made to fit any model perfectly. 
 
THE MAKING OF SOLID AND HOLLOW WAX DUMMIES OF THE 
 BICUSPID AND MOLAR TEETH 
 
 By T. C. Hutchinson, D.D.S., Decorah, Iowa. 
 
 The art of casting inlays, bridges, and the like, with the aid of pressure, has de- 
 veloped a great many ideas, and to the dentist whose inventive genius is given sway, 
 who thinks and works out new possibilities to enable him to do his work more easily, 
 more rapidly and more perfectly, the invention is of incalculable value. 
 
 With the advent of the cast inlay comes the cast bridge, which, in my opinion, 
 will eventually supersede the soldered bridge for posterior teeth, as did the inlay 
 displace the gold filling. 
 
 A great many dentists, in fact I may say the majority of them, have given but 
 little of their attention to bridge work. It is a continual surprise to me to learn 
 from time to time, as I have done, how many of my fellow practitioners overlook 
 this very vital branch of our profession, the rebuilding of lost teeth. Nor can I 
 understand it, for it has been my experience that no work I can do for a patient 
 elates him more or gives him greater comfort than to supply lost teeth by bridge 
 work. You will make a friend of any one for whom you can do artistic and service- 
 able work along restoration lines. 
 
 Fig. 1 
 
 For the average dentist this work should be easy to accomplish, since casting 
 is now at hand, and with the aid of a Hutchinson Bridge Die Plate, for making 
 wax models of the buccal and occlusal surface of the bicuspid and molar teeth, he 
 will have no difficulty. The plate contains one hundred fifty-eight molds of said 
 teeth, in singles, and united in twos and fours, giving ample variety to meet all cases. 
 The teeth have true tooth-like appearance of the buccal and occlusal surface, with 
 perfect alignment, and but a few minutes' practice will enable one to make a wax 
 model and adapt it to the plaster model on articulator and get perfect occlusion. 
 
 Make your abutments, take the impression and bite as usual and, placing your 
 models on the articulator, select a suitable mold on the plate for your case. If you 
 want to make a solid gold dummy, take sheet wax, soften with hot water or a flame, 
 roll to the size needed, then, having previously wet the mold, press the wax into it 
 with your thumb, pressing it in as far as you can, then take a blunt pointed stick and 
 continue the pressing until 3'ou have forced the wax to the extreme depth of the mold. 
 (Be sure to see that the wax reaches the bucco-occlusal points of the mold.) Then 
 finish with the thumb pressure. With a hot spatula or flexible knife trim off the 
 surplus wax from the mold. Lift the model out and you will have a pertect 
 tooth-like wax (lumm>-. Sec Fig. 1. ("ool the wax dumnn- in cold water and trim 
 it to fit between abutments on artii uLitor. ()!itain the alignment (the heat of the 
 fingers will soften the wax so that nou can btiul it lo an\ desired sha|)e), then with 
 
70 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 the hot air s^-ringe heat the occlusal surface, close articulator, thereby getting oc- 
 clusion, or with a knife jou can cut here or there as is needed to make occlusion 
 perfect. See Fig. 2. 
 
 Fig. 2 
 
 To make a hollow wax model, select mold from the plate and then take sheet wax, 
 soften as above and press into mold with your thumb as far as you can, then with 
 soft vulcanite rubber press slowly and steadily, heating the wax occasionally, but be 
 careful not to get the wax too soft as it will tear just as easily as though it were too 
 hard. Heat it just enough to make it elastic. See Fig. 3. Trim off the surplus 
 wax and fit to articulator as above. Cool and cast, and solder 22k. plate on back, 
 completing your hollow dummy You can gauge the thickness of the metal by the 
 thickness of the wax used. 
 
 Should you want to use porcelain facings on part of the dummy, cut off the 
 buccal surface of wax tooth or teeth, having previously backed your facing and oiled 
 the pins. Then force the facing to place, solder the backing to the wax with hot 
 
 P 
 
 Fig. .3 
 
 Fig. 4 
 
 spatula and on the occlusal tip solder with sticky wax, bringing wax over occlusal 
 point. Then remove the facing (note how easily it comes off) and place No. 8 or 
 No. 9 carbon points in pin holes and cast. Drill the carbon out of the pin holes, and 
 cement facing to place. (These carbon points are carried by the dental dealers.) 
 
 It is ad^'isable to make your abutments and dummies in separate cast and solder 
 together. 
 
 When you have used the ai:iovp method of making posterior bridge dummies 
 I tliink you will agree \\ith mc that you have made your last soldered bridge. 
 
LATEST DEVELOPMENTS IN THE CAST GOLD PROCESS 
 
 By Albert L. Le Gro, D.D.S., Detroit, Mich. 
 
 The fundamental principles underlying the process of casting gold will, in ni\- 
 mind, ever remain the same and it is not the latest developments in the process that 
 interest the practitioner of dentistry most, but the latest developments in technique 
 and with the permission of your honorable committee I will treat the subject from 
 that standpoint. 
 
 It is not my purpose to write of the advantages that accrue to the average 
 dentist should he adopt the method of casting gold fillings in his practice, for I assume 
 that from its very incipiency even the most skeptical were quick to see how it would 
 revolutionize certain operations for good in the profession. 
 
 At this stage in the development cf appliances by manufacturers it is a matter 
 of little consequence which machine you select, though in my mind there is a dif- 
 ference which I will endeavor to show you later. 
 
 I have always advocated strict adherence to one method until that particular 
 method had been mastered or found b^' personal experience to be inadequate. If 
 3'ou are using one machine and your neighbor is using another, it does not necessarily 
 follow that because your neighbor is getting better results than you, that his machine 
 is necessarily to be credited with his success. 
 
 In a majority of cases, it is a matter of your neighbor mastering his machine 
 earlier and at the same time developing a technique that is more careful and com- 
 plete than yours. 
 
 Analagous cases are presented in ether lines of machinery, such as automobiles, 
 for instance. Two men ma^' have identical cars, one runs his with a minimum amount 
 of upkeep and trouble and the other is always in trouble and finds that his wa^' of 
 taking care of and running his car is causing the expenditure of a large amount of 
 money as well as time. I merely mention this to show that the man who is having 
 trouble with a certain casting machine is b}.- no means in an anomalous or unique 
 position. He certainly has seen or heard of beautiful castings made by the same 
 make of machine that he possesses, so the natural supposition is that he has left 
 some little detail out in the process of casting which brings about his failure and he, 
 not the particular machine, is to be blamed. 
 
 IXL.A.Y w.\.\ 
 
 Before going into the subject of technique I would like to give you the results of 
 my inquiries as to what ingredients should enter the make-up of a perfect inlay wax. 
 I have found that a combination of gum dammar, carnabaucr and parafifin in the 
 proper proportions will made an ideal inlay wax that can be car\-ed like a fine grade 
 of clay without distorting, attendant fracture, or the use of warm instruments, a 
 method to be deplored and forever banished in trimming wax inlays. 
 
 All except the parafifin are waxes of vegetable origin and can be readily volatilized. 
 The use of beeswax should be avoided, as its addition even in much smaller quantities 
 makes a much softer wax which is more difficult to car\e. 
 
 Waxes that contain animal extracts such as stearin, spermaceta, etc., should be 
 avoided as they separate from the compound in heat, especially in a flame, and they 
 
72 PRACTICAL MANUAL OF DENTAL CASTING 
 
 tend to make the wax greas}^ and flakey. Carnabauer is the hardest and highest 
 fusing of the waxes and is added to give the wax edge strength and hardness, and to 
 make the compound higher fusing. The gum dammar is a hard translucent gum 
 which gives hardness and toughness to the compound. Dammar overcomes the 
 tendency to flake and scale which is characteristic of the wax compounds containing 
 paraffin. The addition of paraffin makes a tough plastic compound which is easier 
 to congeal. A small quantity of ceracin is used to prevent the wax from being 
 brittle and a black vegetable coloring matter is added if desired. A vegetable 
 coloring matter is recommended because it leaves no residue when the wax is burned 
 out. Green should be avoided, as most of the greens which are usable are salts of 
 copper and poisonous. There is a great difference in carnabauer wax on the market. 
 Most of this wax is imported and used for making floor waxes, and while you will 
 find some that is hard as stone, most of it is crumbly and cuts more like an inferior 
 grade of clay. The best grade must be used for inlay wax as the quality of the wax 
 depends largely on the quality of the carnabauer used. I know of no other wax on 
 the market that suits me so well as that manufactured by the Ransom & Randolph 
 Co.; this comes very near to being just what we want. The busy dentist has little 
 time to experiment with matters so small even though he should be thoroughly 
 acquainted with the ingredients and quality of same, that enters into the make- 
 up of such a compound. 
 
 That I may more clearly explain some of my theories as to cause and effect in 
 casting gold it is necessary that I treat of the crystallization of the different grades 
 of gold and the metallurgy of that metal to some extent also. If you will take four 
 nuggets of gold of 18, 20, 22 and 24 karats respectively, and bring them to a dancing 
 molten state and then quickly remove the flame, you will notice that the mass of 
 pure gold, in crystallizing, retains practically the same shape in a crystallized form as 
 it did in a fused state. The 22k. will flatten some; the 20k. a little more and the 
 18k. will be perceptibly flattened. The natural deduction is that the molecules of 
 the gold in the 24k. have the greatest tendency to retain a fixed relative position, 
 and as you go down the scale it becomes very necessary to use more definite pres- 
 sure on lower grades ihan on the pure in casting. 
 
 The pure gold, the melting point of which is 2012 degrees Fahrenheit, and much 
 higher than the lower grades, necessarily crystallizes much slower than the others. 
 About 30 seconds is necessary for the complete crystallization of pure gold; and right 
 here I would like to tell you why I think some machines are better than others, even 
 though beautiful work is accomplished with any of them. When molten gold is 
 forced into a cavity, whether it be by air, centrifugal force or steam pressure, each 
 molecule of the gold used is supposed to have a definite relative position. During 
 the first few seconds in the process of crystallization, pressure should be definite to 
 accomplish this, not increased or decreased, and some means should be furnished by 
 the manufacturers of machines that admit of an intelligent understanding by the 
 dentist of what is going on in the way of pressure during the entire process of crystal- 
 lization. If a machine is not constructed on those lines it should at least admit of 
 the slight increase of pressure from time of application until complete crystallization 
 has taken place. In experiments conducted by myself about a year ago I learned that 
 a definite pressure of 4 pounds, if absolutely definite during the entire time of crystal- 
 lizing, was infinitely more accurate than those that ranged from 30 pounds down, 
 with no fixed pressure at any time. My own supposition is that the molecules were 
 not held in their correct relative position during the entire period of crystallization 
 
LA TEST DEVELOPMENTS IN THE CAST GOLD PROCESS 73 
 
 and though the inlays were just as perfect to the naked eye, they did not fit into the 
 cavity with the nicety that the one of 4 pounds' definite pressure diti. H\en greater 
 discrepancy is shown in the use of different grades of g<jld. The common allo\s of 
 gold are silver and copper, either one of which tends to make the gold more sluggish 
 than the pure gold. The lines in the finished casting of an allowed gold are not as 
 sharp and it is therefore not deemed advisable to use anything but pure gold in cavities 
 of extreme shape, for it is a rare case that presents no defects when the lower grades 
 of gold are used. If alloyed gold must be used, I would suggest that gold alloyed 
 with copper or platinum or both be used. Copper does not materially lessen the 
 malleability of gold, while at the same time it hardens it. Silver is objectionable at 
 all times as an alloy for gold that is used in casting. It has been recently recom- 
 mended by some well known dentist on account of the color produced, but it is a 
 mistake to use gold alloyed with this metal, for aside from making the gold very 
 sluggish, it has little edge strength and will not make what I call a perfect inlay in 
 cavities of extreme shape. 
 
 With a little experience you can learn to distinguish the alloy in any gold com- 
 bination on sight. A yellow tint generally indicates equal parts of silver and copper. 
 A red tint, an excess of copper. A green tint, an excess of silver. One of the most 
 desirable alloys for cast inlay work is composed of Gold, 22 Dwts., Plat., 18 Grs., 
 Copper, 3 Grs. It is a rather difificult alloy co produce but makes a sharper casting 
 than any other I have been able to find as there is very little oxidation compared with 
 18, 20 and 22k. golds that are alloyed with silver and copper. I do not recommend 
 this alloy for its ductility or malleability, for, like most of the alloys, it is sadly 
 deficient, but it is much superior to gold alloyed with silver as regards color and will 
 make a sharper casting. 
 
 In regard to the latest developments in technique — there are a multiplicity of 
 methods, all of which it is not my purpose to treat. I will confine my remarks to 
 the little hints that my own personal obser\'ation and experience have taught me. 
 As you all know, the possibilities of this work are only limited by the skill and 
 ingenuity of the man. So many different possibilities suggest themselves to different 
 men in this work that it would be presumptuous on my part to attempt to tell you' 
 of all the new things that everyone has worked ouc. 
 
 In the May and June, 1908, numbers of the Items of Interest are two very 
 interesting papers by Dr. Price, of Cleveland, which are well worth the time of any 
 dentist, and while the deductions of Dr. Price are not verified by my own personal 
 experience, there is much of interest in these articles that show thought and study. 
 These articles come the nearest to working out the problem and are the only papers 
 on casting gold that I have read that exhibit an intelligent knowledge of the condi- 
 tions as they are. 
 
 SECTIONAL IXL.WS 
 
 These are used only in cavities of extreme shape where the caries has attacked 
 the tooth to such an extent that it becomes necessary' to retain all the solid tooth 
 structure that is left. Take a cavity in a large molar approximal involving the oc- 
 clusal angle with the diameter bucco-lingually much larger at the cervical than at 
 the occlusal portion. The cavity is so large bucco-lingually at the cervical portion 
 that: in order to prepare a .solid or one-piece inlay, it would be necessary to cut dawn 
 a consi(k'ral)ie pordon of good solid tootli strurlure. To a\()id tills the sectional 
 inUus or t\\'o-|)ierr inhns arc i'ni|)l()\'e(l. These inla\s should be niadt' hollow l)\- 
 carving the wax inlay or b>- the use of suction and heat. 1 ha\e been using a suction 
 
7 A PRACTICAL MANUAL OF DENTAL CASTING 
 
 apparatus that is now on the market and while it is a great improvement over 
 the carving, it is quite crude. This defect will be overcome, I have no doubt, as the 
 evolution of casting gold progresses in dentistry. The orifice of the hollow cavities 
 should be so carved that where the two sections are in place the cement will form one 
 solid mass running from the hollow in one section to the hollow in another. 
 
 Some one has suggested the use of ethyl chloride on cotton for chilling wax 
 inlays. I have found it very satisfactory also in rubbing a smooth surface on the 
 outside of wax inlays. When the wax inlay is removed from the mouth it should be 
 washed in soda water to remove the mucus which sometimes produces a surface on 
 the gold inlay that you cannot account for otherwise. 
 
 DITTMAR CAST SHELL CKOWN 
 
 I shall describe the Dittmar method for casting a cast gold shell crown, for I 
 think it the most perfect gold crown ever constructed. If you must put on gold 
 crowns and can get a good fee for them, the Dittmar method will enable you to 
 portray nature as no other method will and at the same time enable you to construct 
 a crown that will give the minimum amount of irritation to the gums. After the 
 root and remaining part of crown have been ground down properly, take 34 gauge 
 pure gold, make band to fit. This gold is so thin and soft that an absolute fit can 
 be burnished slightly under the gum. Trim band proper height for top to be soldered, 
 which completes an ordinary box cap. Have the top and band fit accurately so that 
 the minimum amount of 22k. gold, not solder, will be used to solder the two together. 
 I recommend 22k. gold for soldering for without it, the gold used in casting will melt 
 a lower grade of solder and percolate or racher be forced in fine films up inside of the 
 band. When cap is completed place on root and with modeling compound in a 
 double articulating impression tray, take the bite and impression at the same time. 
 Articulate plaster for articulating side and inlay investment compound for crown 
 side and paint the adjoining teeth with oil. Now heat up a quantity of inlay wax 
 and use camel's hair brush to build up wax on the cap to proper contour and 
 articulation, smooth surface with chloroform, saw off adjoining teeth and then the 
 waxed crown. Invest and cast. The possibilities here are great and most beautiful 
 work can be accomplished. 
 
 GOLD AND TIN INLAYS 
 
 To use an inlay made of a layer of tin and over it a layer of gold at first thought 
 seems a good procedure, but the only argument that I can see logical in its favor is 
 the economy of gold. A combination tin and gold inlay can have no other par- 
 ticular advantage over a gold inlay for the layer of cement must come between the 
 inlay and tooth substance and all the arguments used in favor of tin at the cervical 
 third or half of the cavity are lost. The ideal procedure is to insert the tin with 
 pluggers, burnish the top and then make a cast inlay of gold to finish the operation. 
 To make a combination tin and gold cast inlay is somewhat difficult, at least it has 
 been so in my own experience. After preparing the cavity a wax inlay is made of 
 the cervical third or half of cavity. The top of this wax is made smooth and then 
 oiled. On top of this another wax inlay is made to come flush with borders of re- 
 maining portion of cavity and to restore occlusal and approximal contour. This 
 part of wax is then removed and cast, leaving the cervical portion of wax still in cavity. 
 When the occlusal portion is cast the gold is heated slightly, placed in position in 
 the cavity and then withdrawn, when the cervical portion or remaining wax will be 
 seen to be attached to the gold already cast. Now comes the most difficult part of 
 
LA TEST DE VELOPMENTS IN THE CAST GOLD PROCESS 7o 
 
 the operation. Gold has a great affinity for tin and the ilask holcHng the in\est- 
 ment must be at about an exact temperature to cast the tin. Tin melts at 442 
 degrees Fahrenheit and is not sensibly volatile, so if the investment is heated until 
 the wax is entirely burned out of the investment and there is no formation of gases 
 continuing and then allowed to cool until about 400 degrees Fahrenheit, melting the 
 tin now with blow-pipe, using no more than the required heat of about 450 degrees, 
 a successful casting on the gold inlay can be made. 
 
 If these instructions are not followed out, the gold under a greater degree of heat 
 will entirely absorb the tin and a brittle lead color mass will be the result. Hydro- 
 chloric acid must not be used under any circumstances to pickle the filling as tin 
 dissolves in the acid with the evolution of hj'drogen and formation of Stannous 
 Chloride. 
 
 COMBINATION GOLD AND PORCELAIN INLAYS 
 
 One of the most satisfactory operations in large restorations is the gold inlay 
 with porcelain face baked in. The inlay is made in the usual way, preferably with 
 platinum alloyed gold. The wax inlay is carved out or sucked out with heat and 
 air on the wax corresponding with the portion to be restored in porcelain, with 
 undercuts. After the inlay is made, Jenkins porcelain is baked in and an esthetic 
 result is accomplished. Before baking in the enamel, place gold inlay in cavity, 
 burnish borders and reduce line of gold on exposed border between margin and 
 cavity for porcelain to a minimum so that the line of gold will be almost imperceptible 
 when work is finished. 
 
 PORCELAIN CROWN WITH CAST CAP AND DOWEL FOR BADLY BROKEN 
 DOWN ROOTS 
 
 This is a branch of the work of Drs. F. Ward Hewlett and C. J. L^'ons, of 
 Jackson, Mich. They have worked together practically in producing a technique 
 that gives very fine results in these extreme cases of badly broken down roots. I 
 first saw the work of both these gentlemen, introduced at Indianapolis, early last 
 year, and after mastering it to some extent have gotten very satisfactory results in 
 my own practice. An article on the subject, with detail drawings by Dr. Howlett, 
 appeared in the January issue of The Dental Summary. Every dentist should 
 read it. I will give briefly the technique: 
 
 HOWLETT'S CROWN 
 
 A bite is taken over the abutment to be crowned with Stent's modeling com- 
 pound, which is very hard when cold. The compoimd is then carved to fill the space 
 and imitate the crown to be restored. A thin platinum matrix is then swaged to the 
 occlusal surface of the tooth which has been built up and carved from the compound. 
 This matrix is then removed from the carved tooth and filled with porcelain by a 
 series of bakings which results in a cap of porcelain such as might be stamped from 
 gold in the die plate for a gold crown or bridge dummy. A second matrix of plat- 
 inum is made on the root stump or abutment and porcelain built onto it, restoring 
 a considerable part of the tooth. This is then placed on the stump in the mouth 
 and the occlusal part of the crown first made is wa.Ked on top of it and the patient 
 forces it to proper occlusion while the intervening wax holds the two sections of 
 porcelain together and in place. The crown is then removed from the mouth and a 
 portion of the wax removed and replaced with porcelain. Then the rest of the wax 
 is removed and the space filled with porcelain and the whole crown is fused together 
 into one piece. 
 
7G PRACTICAL MANUAL OF DENTAL CASTING 
 
 lyon's crown 
 Dr. C. J. Lyon's crown, which differs somewhat from that of Dr. Hewlett's, 
 though the fundamentals are practically the same, is a porcelain crown with cast 
 cap and dowel for badly broken down roots. Use iridio-platinum post gauge 20 as 
 a matrix for carrying wax inro the root, letting the wax extend over the gingival 
 margins of the root. This should then be carved to form a plate for the crown; a 
 square post should be formed in wax about 5 millimeters long and set in the middle 
 of the plate for the reception of the crown. The wax model of the cap and dowel is 
 then cast in pure gold with the iridio-platinum wire in the center, after which it is 
 polished and set in the root. A platinum matrix is next made of the plate and post 
 by forming a tube for the post and soldering to a square piece of platinum; after- 
 wards it is burnished to a perfect adaptation to the plate and post. A Davis crown 
 is used for the body of the porcelain crown by grinding out a section from mesial 
 to distal large enough to accommodate the post. This is waxed in position over the 
 matrix and all withdrawn and Consolidated body packed around the matrix and 
 fused. After the crown is completed the matrix is removed from the crown and the 
 crown is cemented to the cap and dowel. 
 
 BRIDGE WORK 
 
 Those who have had experience in casting bridges in one piece will agree with 
 me that it is entirely the wrong procedure and especially where inlay abutments 
 are employed. There is no known investment compound that when set, even under 
 perfect conditions, will expand enough to compensate for the contraction of gold 
 when crystallizing. It is therefore necessary to cast bridges in sections and solder 
 together in order to get exact results. 
 
 The fallacy of casting directly onto porcelain, I think, is quite well recognized. 
 Such methods have no other claim to general adoption than that they are an "eas}' 
 and rapid method or means of obtaining a result which cannot be wholly successful." 
 In conclusion I will say that it has not been the object of the writer to assume 
 that there is any "only way" in the processes of casting gold, and while the subject 
 given me by your committee is not one that I could possibly stick to the text on, 
 my initial object will be accomplished if this paper but serves as a stimulus to bring 
 out many instructive facts that you all must possess on this subject. 
 
 DISCUSSION 
 
 Dr. M. R. Muir, Detroit: Cast gold inlay work is not yet two years old, and everybody has his 
 own little ideas, and we should have an expression from everyone here tonight who has had any ex- 
 perience in this work. 1 hoped to have some specimens to show you tonight, but I have only one which 
 is a practical case that I made this afternoon — a bicuspid crown with a porcelain face in it. The facing 
 was removed and gold cast with lead pencil points in the pin holes to keep them open, and the facing 
 is then attached by cement. 
 
 The subject of Dr. LeGro's paper must necessarily bring out the results of his own experience, 
 and as it is largely original it is of much more interest than if he had obtained his ideas from books 
 and magazines to which we all have access. 
 
 The latest processes in cast gold work are being developed by dentists every day in their own 
 ofifices as the possibilities of the work done, by casting gold is, as the essayist says, limited only by the 
 ability of the operator. There has been comparatively little on this work in the dental journals in 
 the last eight or ten months; nothing important during that time in the Items of Interest or the Cosmos, 
 with the exceptions of the results of the work done by Dr. Price, as given in his splendid articles ap- 
 pearing in the May, June and December, 1908, Items. 
 
 The seed was sown by Dr. Taggart when he addressed the Odontological Society of New York, 
 just two years ago tomorrow, giving to the profession the results of his labors and since that time it has 
 taken root and flourished in nearly every dentist's office in the country. Numerous kinds of machines 
 have been designed with a view to economy and the use of the cast gold inlay has been unmercifully 
 
LA TEST DEVELOPMENTS IN THE CAST GOLD J'ROCESS 77 
 
 abused by some. Dr. Ilasley, in the January, 1909. hems, says that some of the machines are so 
 far removed in form and action from the usual workroom apphances that until seen in operation they 
 might pass for caricatures. One's thumb guarded by a wet rag, has been found sufficient to force 
 molten gold into a mold so as to produce an acceptable inlay. Compressed air, steam, gun powder, 
 inertia, centrifugal force and atmospheric pressure brought into action by an exhaust pump, a pill 
 box, a child's toy tin pail swung around one's head, a pair of tongs, a Yankee clock, an old fashioned 
 coffee mill, and a hundred and one such like devices have been suggested in the dental journal for inlay 
 castings. Just here let me quote an expression of Dr. Price: "You are disappointed just in pro- 
 portion to the height of your ideals." Therefore, I would say, govern yourselves accordingly in select- 
 ing a machine. 
 
 I agree with the essayist in advocating a strict adherence to one method or machine that you 
 know others to be getting good results with, stick to it yourself until you get results. Exactly the same 
 can be said about inlay wax. I can get the same results with the wax I use that you can get with the 
 wax you use, and you can get the same results with the wax you use that I can get with the wax I use, 
 which goes to prove that the wax for you to use is the wax that you know how to use. 
 
 There are several substitutes for pure gold which might be used in casting for anything but inlay 
 work. My experience has been that nothing takes the place of pure gold for a perfect inlay. The 
 only argument to be put up in favor of the alloy or any other material that might be used is economj', 
 but I would not consider that, as the time consumed is the same and results are not as good, when alloys 
 are used. 
 
 Sectional inlays are often employed to good advantage and are sometimes necessary to avoid 
 unnecessary cutting. If there is an undercut and the overhanging walls are good and strong, fill it 
 with cement before taking the impression. After the sidewalis and margins are prepared, if there 
 still remains decay in the bottom that if removed would make an undercut, take the impression and 
 remove the decay after. A great many are of the opinion that grooves placed so and so in the cavity 
 and in the inlay for the cement to lodge in help materially to hold the inlay in its place, but I believe 
 that the less cement you have between the inlay and the tooth the stronger and more permanent 
 it will be. I had that ground into me by Dr Reeves and it is still there. 
 
 On account of the perfect fit obtained with the cast gold inlay by burnishing, in certain cases with 
 plenty of mechanical retention one can afford to sacrifice sofne of the strength given by the cement 
 and I frequently hollow out large inlays v/ith the Roach suction wax carver to save using so much gold , 
 or to make a layer of cement over the pulp to protect it from thermal changes. Your inlay will lit 
 better and give better satisfaction if you will clean it with hydrofluoric acid after casting. A porcelain 
 face may be baked into a gold inlay, or the cavity can be prepared in the inlay before setting and after 
 it is set proceed in the usual way to make the porcelain inlaj'. 
 
 I do not know of a better way for chilling and removing wax inlays from the cavity than the 
 following: In the left hand hold a small abscess syringe with platinum point filled with cold water 
 and with the right hand heat the end of a piece of copper wire about two inches long over a flame and 
 insert it into the wax inlay — immediately then put a stream of cold water on the wire and the inlay — 
 this holds the wire in its place. The water all going directly to the place where needed and the point 
 of the syringe being small, the amount of water used is small. While cooling the inlay with the left 
 hand pick up the pliers with the right, grasp the wire close to the inlay and remove. At this point 
 clean it off with a cold air blast from your air syringe, using from 10 to 20 pounds' pressure. To remove 
 the inlay from the wire, heat the wire in the center over a small flame and the inlay will fall off. A 
 good wax inlay can easily be spoiled by hooking an exploring point into it and pulling and partly 
 shoving it out as is necessary, especially if it fits tightly as it should. I do not think there is a machine 
 made that will cast a plate or bridge without getting some shrinkage, enough so that it will not fit; 
 I have never seen any, and have tried it — unless it can be done with Dr. Price's artificial stone. He 
 claims great things for that, and I hope that he will be at our February clinic, and I will let him speak 
 for himself at that time. That artificial stone, if it is not perfected now, I think will be some day. 
 and will be the only method of casting large inlays, plates or bridges. A bridge can be cast separately, 
 the dummies, and then the parts soldered together, but I do not think that there is a machine made 
 that will cast a large bridge or plate that will fit. 
 
 Dr. M. L. W.\rd, Ann Arbor: There are two points that the essayist brought out that I would 
 like to emphasize. The first and most important one was in regard to the kind of gold. I was of the 
 impression some time ago that only pure gold could be cast successfully. I am of the same opinion still 
 so far as most fillings are concerned, because the pure gold admits being finished better to the margins. 
 I am not certain, however, that it is the only one that we can depend upon for some other kinds of 
 work. Day before yesterday I cast a practical case out of 18K gold plate, by cooling the mold down 
 before casting. It appears to me that the great trouble is not entirely with the shrinkage of the gold 
 
78 PRACTICAL MANUAL OF DENTAL CASTING 
 
 but in the manner of handling it. Everybody has an idea that they should cast inlays into a hot 
 mold while in foundry work it is just the reverse, and so far as I can see, it should be so here. Gold 
 will shrink on cooling, but it will shrink much less if cast into a mold cool enough to be handled in the 
 hands, than it will if it-is cast into a mold that is glowing hot. I believe 18, 20 and 22K. plates can be 
 cast reasonably accurately into abutments, saddles, etc , and there will be little more shrinkage if any 
 at all than if they were made of pure gold. Such golds, however, will not make nice margins for fillings. 
 If the gold is heated with the ordinary blow-pipe the whole investment is usually heated much too hot. 
 The heating of the gold should be done with the oxyhydrogen blow-pipe, using a small flame so that 
 the investment remains cool. Even though the small flame is used with the oxyhydrogen blow-pipe 
 it takes only a few seconds to melt the gold to the proper state of fluidity I cannot speak with too 
 much emphasis about the necessity for not overheating the investment and the necessity for casting 
 into a cool mold if we get the minimum amount of shrinkage of the gold. 
 
 Another thing of importance in this work is the pressure under which the gold is cast. I have 
 found that all of the present investments are too weak to stand sudden high pressures and those that 
 have been overheated are especially weak. Almost all of them, one or two of them fundamentally 
 strong ones, will stand open flame of the Bunsen burner from eight to fifteen minutes without a great 
 deterioration in strength, though every minute or two beyond fifteen minutes seems to convert it into 
 a drj' powder. Another thing of importance in the casting process is the keeping of the gold at the 
 proper condition as regards fluidity. All of the golds almost lose their identity after being cast the third 
 time. They take up contamination from the investment in the form of iron, and iron is found in all 
 of the investments Gold will become contaminated from the blow-pipes sufficiently to prevent its 
 casting perfectly. A good thing to correct this is to melt the gold and place upon it gradually, keeping 
 it melted all the time, equal parts of potassium nitrate and borax. The flame should be directed onto 
 the gold from one side until it is melted, and little by little add the potassium nitrate and borax. Usually 
 three or four minutes is sufficient, but if it is desired to raise the karat considerably, it will take some- 
 what longer than this. The oxygen supplied by the potassium nitrate oxidizes the base metals and they 
 are carried away 'n the slag. This is a standard dry process for refining gold and one which every den- 
 tist can use to advantage in connection with the casting process. It is both clean and handy and is 
 particularly effective in removing iron as well as many of the other contaminations found in gold 
 that has been used for casting. 
 
 Dr. S. Becker: I would like to hear from some one, his experience with Acolite, which I have 
 used considerably for attaching porcelain crowns to badly decayed roots. I expected to find something 
 in the paper on this material. I have used it considerably. In fact, I have not put on a Davis crown 
 since June without either a gold or Acolite fitting. I have used the gold for large crowns once or twice, 
 but it takes so much gold as to be prohibitive. Acolite has a good sharp edge but has no strength. 
 I do not like to cast gold on the porcelain, for the reason that we are liable to check the porcelain, 
 because of the difference in expansion of porcelain platinum pins in the tooth and the gold used in 
 casting. I do not think Acolite has been generally used for so long but what we want to know some 
 more about it. Many people cannot afford to pay for the gold, especially in attaching I-ogan crowns, 
 where you will often find there is a big space on the lingual side. I have filled these spaces by casting 
 direct to the porcelain, and with the Logan crown I can do it very nicely with the Acolite. but whether 
 that is going to stand I am not prepared to answer. 
 
 Dr. Muir: I think you can cast just as well on porcelain as any other way, but I do not think 
 it is advisable. I do not think it is necessary. In' the first place, it changes the color so much. I 
 have cast some on porcelain and have never cracked a tooth, but they have all been experiments, as I 
 have never done a practical case in that way. I think they are just as strong, and I think the tooth 
 has more and better protection if the gold is cast on it than any other way. I do not see any necessity 
 for checking a tooth while casting on it. but don't think it is desirable, because it is liable to change 
 the color too much. I think it can be done just as well by cementing the facing after the casting is 
 all complete. 
 
 I think I did have to grind the crown I am showing a little; I took just a little bit off the gold 
 and ground the porcelain a little. There is some change due to a certain extent to the contraction of the 
 gold. I do not think there is any machine made but that there is some contraction. In an inlay for 
 a filling that can be taken care of by lapped margins and you can burnish it down so that you cannot 
 detect the margin, but on a curved tooth as this is, you have to grind a little olT to allow the facing 
 to go into that gold. It may have baen due to the shrinkage of the gold, and it may have been due to 
 the distortion. I did it hurriedly because I wanted to get it ready to bring over tonight. J do not 
 think that is any argument against the use of the method, because that tiny bit of grinding can be done 
 with the articulating paper. 
 
LA TEST DE VELOPMENTS IN THE CAST GOLD PROCESS 79 
 
 Dr. a. W. Dumas: I wish to speak in regard to the advisabiUty of casting gold onto porcelain. 
 I do not think any casting machine should take the credit of a successful casting of that kind, the credit 
 should be given to the operator, who first heats his case and porcelain to the same degree of heat as 
 the molten gold, because otherwise you have about the most powerful elements in nature, heat 
 and cold, in contact, and unless you have your porcelain heated to the degree of your gold, you are 
 sure to have trouble. I have been successful in many cases in casting upon bare porcelain, but I think 
 it is folly to take such a chance. I think it is wiser to take a piece of pure gold and anneal it and burnish 
 it over the tooth; in that way you save time and will not crack your porcelain. The cracking of the 
 porcelain I think is due to the platinum pin in the tooth. I believe that as soon as the molten gold 
 strikes these pins there is an expansion of the pins which causes a fracture in the tooth. You may 
 take a Davis crown, and you can cast your metal, gold or Acolite upon it without removing, cast the 
 whole at once, and the metal will find its place into the inside of that crown so that it will be impossible 
 for you to take it out. From that I should infer that the cracking of the porcelain was due mostly to 
 the expansion of the platinum pin baked into the tooth. I think it is economy of time and everything, 
 to burnish a small amount of gold against your porcelain. 
 
 Dr. Muir: The credit should not be given to any machine for casting on the porcelain; it can Le 
 done with any machine. I do not advise anybody to do it. I say it can be done, but it is not desirable. 
 If you will heat the case hot enough to get the porcelain so hot that the gold will not check it, it can be 
 done in any machine. The facing has got to be hot for the same reason that when you cast on plati- 
 num or cast on gold plate, they have got to be hot so that the new gold will fuse onto them, and it will 
 fuse onto them. This cast that I passed around has a platinum band. You cannot expect the hot 
 metal to unite with a cold metal; the inside of the mold has got to be hot. 
 
 Dr. C. H. L.^nu: I want to help you out a little on the casting. It is utterly impossible to fuse 
 any kind of metal to a piece of porcelain. It was never known to happen. You can flow it over a 
 piece of porcelain. Whenever a piece of porcelain and platinum come together, the difference bctA-ecn 
 the shrinkage and the expansion of the porcelain causes the porcelain to crack from the stress on the 
 pin. If you look at a piece of window glass upon which you see various designs, these are made by 
 putting glue over the surface of a smooth piece of glass and allowing that glue to dry, and in doing so 
 it rips out the design. You can never fuse onto a vitreous glass or porcelain a metal that it does not 
 change the same; it simply rips off the design. It is far stronger to cement a crown onto a metal base 
 than to fire it on. Every Logan crown is weak in that respect. Every bit of porcelain is fused in the 
 mass; and from the piece of metal inclosed we will always have stress upon it, so that the tendency is 
 to burst when it is re-heated. Cement your crowns instead of fusing them. If there is no strain upon 
 a piece of porcelain it will stand indefinitely if you do not fire-crack it. If you fire a piece of porcelain 
 on a metal base as in continuous gum work, it will change, carrying the metal plate with it; and the 
 fractures are not enough to talk about; or it will peel off and leave a nice shining surface, and the 
 thicker the metal the more it will fracture. To prevent fracture by the heat when soldering facings, 
 before the gold is cold take a piece of asbestos fiber and cover the piece so that it cools slowly and 
 it will not fracture. I have worked this hundreds of times and never had a fracture when I took thai 
 precaution. 
 
 Dr. LeGro: I do not think that the dentists have any intelligent understanding of what is going 
 on when they are casting gold. They know that they are getting results but do not know what the 
 cause of it is. They have not gone into the metallurgy of gold, or effect of pressure, and that is some- 
 thing that we have got to get an intelligent understanding of before we reduce this to an exact science 
 or practice. As I stated, we have a great many articles published in the different dental journals, 
 there is but one man who has written a scientific paper on this subject, and that is Er. Price, of Cleve- 
 land. Of course, he is in a position to go into this scientific research more than the rest of us. I am 
 rather disappointed, therefore, that it was not more discussed from the scientific aspect. However, 
 I expected an "experience meeting," and such meetings always give us much to think about. 
 
80 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 CAST GOLD CROWN 
 
 By C. E. Meerhoff, D.D.S., Chicago, 111. 
 
 Especially adapted for bridge abutments. Trim root, fit band of 35 or 36 
 gauge platinum (or gold), stove pipe shape. Xip end of bands and bend over 
 root. (Fig. 1.) 
 
 ^^ ^9 
 
 D 
 
 i 
 
 Have patient bite into wax, giving exact articulation. (Fig. II.) 
 
 Carve to correct shape and with bur or suction remove wax from inside as 
 desired. 
 
 Pass quickly through alcohol or Bunsen flame, or rub down wax with chloroform 
 to finish or smooth wax. (F"ig. III.) 
 
 The crown on model has not been touched by buffer or wheel. 
 
 ADVANTAGES 
 Strength — Thickness of metal external to band makes crown unbreakable. 
 Definite seat — Ease of adaptation of thin metal obviating irritation at gingival. 
 
 CAST JOINTED LOGAN CROWN 
 
 By C. J. Burris, D.D.S., Washington, Ind. 
 
 The jointed Logan crown is by no means new, but is perhaps being used more 
 since the advent of casting. It is especially advantageous in cases where from decay 
 or otherwise the tooth structure has been lost to an extensive degree beneath the gum 
 line. 
 
 After the tooth root has been prepared as in cases for the Logan, select a removable 
 pin crown with due regard to size and shape and grind to a joint beneath the gum 
 line on the labial surface only. Then by use of an iridio-platinum pin join the two 
 parts with inlay wax and press to place against the tooth root. Remove and trim 
 away the surplus wax, replace and burnish wax around the tooth root. The crown 
 can now be separated from the pin and wax and the latter invested and cast pref- 
 erably by the use of pure gold. 
 
 This method gives increased strength to the pin as well as the adaptation to 
 the root surface; the parts can now be united with cement and when finished are ready 
 for setting. 
 
THE CAST GOLD INLAY 
 
 By James W. Lyons, D.D.S., Jackson, Mich. 
 
 It is a very great pleasure for me to appear before you at this meeting, one of 
 the very auspicious occasions in the history of this society. 
 
 I am pleased to give you the best my feeble ability may permit on this subject 
 which has interested the profession of the world and centered all c^cs and thought 
 upon an American dentist and an American city. 
 
 I may be unable to ad\'ance any new ideas, but I might present some thought 
 in a light that some one may be benefited in the use of this method. 
 
 It is but just to give credit to those few constructive geniuses that are found in 
 our profession. There is not a great number among those who ha\e taken up 
 dentistry as a life work to which we may point in either scientific or mechanical 
 research who stand out pre-eminently above all their fellows, but our ranks are full 
 of men, clean-cut, shrewd and wide awake to every progressive step forward made 
 by the other fellow and are capable of applying the ideas and either simplifj'ing or 
 enlarging upon them, cutting and trimming away the corners, or rounding them out, 
 thus making them all the more practical and useful. 
 
 It is true that many men's lives are so filled with work that they do not have the 
 time to grasp and assimilate or even to try out the many valuable methods that 
 are created for their benefit. We find a great many dentists who have long been 
 accustomed to following out one specific plan in their work. They ha%e, of course, 
 learned b}' pursuing this plan, to do their work well and comfortably and rather dread 
 to get out of the rut and accept anything in the way of an innovation. 
 
 A departure from the use of foil and the mallet and the adoption of the inlay 
 requires much effort on the part of many dentists. 
 
 Two years ago I had the pleasure of presenting a paper on the gold inlat' before 
 this society. It is, indeed, remarkable, the progress made in these two years, 
 and I greatly appreciate, when I read over the paper I prepared at that time, the 
 importance the gold inlay has established among our many valuable fillin.g materials. 
 
 ADVANCE BEING M.ADE 
 
 Do you comprehend the advance being made along mechanical and artistic 
 lines by our careful and observing operators today? 
 
 To keep apace with the times, is there one thing that makes it more obligatory 
 upon us than to get out and come in contact with the men who arc doing things? 
 When I meet and talk with a man who locks himself within his own surroundings 
 his conversation upon dental topics has a like bearing to the knowledge possessed of 
 current affairs b}' the man who never sees a daily paper. 
 
 The gold inlay came to us because within our minds there was a demand for 
 just such an institution. We receive from mother nature many inventions at just 
 such a time as when our surrounding conditions demand them. Our minds become 
 imbued with the desire to accomplish some especial purpose and by concentrating 
 thought along that line we develop that for which we are stri\ing. At first our ac- 
 complishment may be crude, but by still further thought and l)y the application of 
 scientific principles it Is impro\ed and made better. 
 
82 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Esthetic appearance brought to us the porcelain, which, be it beneficial or be it 
 detrimental, our enthusiasts placed in all cavities regardless of location, but the more 
 conservative man felt the need for a material which would better withstand the 
 battering of mastication. 
 
 Manipulatory skill gained with the burnishers in burnishing the platinum 
 matrices to the cavities developed the idea of thus shaping a matrix and flowing it 
 full of the gold and employing it in large molar and bicuspid restoi-ations, by such 
 a material enhancing the value of our operation as to durability and overcoming 
 the friable edge of porcelain. With this inlay of gold we had accomplished much, we 
 had rendered inlay work more practical, and we had achieved much to better our 
 services to our patient, but as we went along in the practice of these methods the 
 only thing we seemed to be gaining was manipulation; we were learning to make 
 closer adaptations, we were studying methods of producing the least amount of 
 shrinkage, methods of procuring the hollow inlay and various peculiarities to obtain 
 an ideal form to get the most perfect restoration of lost tooth structure. 
 
 When the time became ripe it was left to Dr. Wm. H. Taggart to bring before 
 the profession probably the greatest achievement of the present century, "The cast 
 gold inlay," and you wonder why you did not conceive of this system of producing 
 the inlay, but as I have said before in this paper, we find the results of concentrated 
 thought along this particular line. Dr. Taggart spent many weeks and months 
 experimenting before he developed the proper idea of producing that which he sought. 
 He had the completed product in his mind and was working to achieve that particular 
 result with which he was crowned with success. 
 
 THE CAST INLAY 
 
 The cast inlay is certainly the highest ideal in the gold inlay. At one great 
 stride Dr. Taggart placed all our matrix inlays so far in the background and out of 
 date that they will never be resurrected. What an ideal method, when we can take 
 a piece of wax and shape a wax filling in the mouth, restore occlusion and contour 
 in its most minute form and then duplicate that in gold so that it fits the cavity, to 
 absolute accuracy; it is most emphatically a great triumph in dentistry. 
 
 The method is but just in its infancy and yet its field seems unlimited. Almost 
 every day presents some phase in practice in which we can apply the principle with 
 the most remarkable and gratifying results. 
 
 Besides the inlay filling, it is admirably adapted to the restoring and building 
 up of badly decayed roots for the purpose of crowning. 
 
 Ideal for anchorage of small bridges, repairing broken Logans, casting cusps, 
 dummies and for a multitude of uses. Even if Uncle Sam would just guarantee us 
 to keep out of the game we might even be able to retire from the practice of dentistry 
 by casting gold dollars. 
 
 But, ladies and gentlemen, talk is cheap — just wait a bit. A few years ago we 
 had men who couldn't find a cavity but what it came under the indications for a 
 porcelain inlay. They even seemed to look upon, with scorn and contempt, the 
 operator who, a little conservative, had evidence about his operating room that he 
 had use for, sometimes, gold, tin and amalgam. 
 
 Today the conservative man has been wise, the other fellow is wiser; if he isn't, 
 some one else has his patients. 
 
 We are even again hearing the same class of operators who always grasp a new 
 method and ride it to death as a hobby, making the assertion that the day for mal- 
 
THE CAST GOLD I NLA V 83 
 
 leting in gold and for the old amalgam arc gone, that they do not expect to make use 
 of the malleted gold filling again. 
 
 It has always been a question with me, upon which I have not as vet passed 
 decision, whether these men, faddists, if you please, are really a benefit or a detri- 
 ment to our profession; my judgment is that they are at least enemies to themselves. 
 
 The cast inlay method is a great achievement in art and mechanics and I appeal 
 to you all not to abuse it. By carrying out this method carefully it does for us what 
 no other method ever accomplished to the same extent. Owing to the absolute 
 accuracy which you must obtain, it develops in you, unconsciously, a high degree 
 of skill. 
 
 Gentlemen, do not assume the idea that all that is rccjuired to make successful 
 inlays is a particlular kind of machine. Vou have much to learn to l)ecome an inlay 
 worker. 
 
 A gold filling thrown into the tooth most any way, pro\i(ling you happen to 
 have two opposing angles or pits, may stay long enough for the patient to move out 
 of your locality, but an inlay inserted regardless of conditions stays a mighty short 
 time. 
 
 The very highest art and skill arc demanded in cavity preparation for inlays. 
 
 I believe a man will be able to do a very much better gold filling after he has 
 done inlay work for a time, for the reason that his training in the thoroughness of his 
 cavity preparation will instill into him the idea of very superior formation to what 
 he has been accustomed to. 
 
 It has been suggested that the casting of fillings might have a tendency to 
 cheapen our operations. Some men argue that as it is easier on them and dees not 
 take so long as to mallet in a filling, our fee should be less. For those men let me say, 
 they should belong to the union labor crowd, where they could operate under a scale 
 of wages. 
 
 It is too burdensome to my minfl to work out a classification for such men among 
 scientific and skillful dentists. 
 
 How unfortunate it is that our colleges cannot wake up to the fact that our pro- 
 fession needs fewer men, and iJiose with high ideals, and not great numbers, who as 
 failures in the highest arts in dentistry, might make the very best of machinists or 
 blacksmiths. 
 
 This class of work should demand the closest application, plenty of time, and the 
 best of your skill, all of which call for the best of fees. 
 
 It is a great mistake with the young men entering the profession in taking up 
 chc inlay as an easy method to a result, thinking, by so doing, of his abandoning the 
 long, tiresome gold filling, when their experience has been so limited as to be unable 
 to discriminate between the indication for filling or inla^-. Their manipulation of 
 filling materials is needed, their judgment and observation more mature. 
 
 You will find your patients very appreciative of a method which restores their 
 broken down molars and bicuspids so excellently to usefulness, with so little incon- 
 venience to themselves. 
 
 How much higher the ideal as compared with the gold crown which, at its best, 
 is so ill-fitting around the gingivae which nature so admirably formed. 
 
 How perfectly the inlay replaces so many defective, unsighth- and ofttimes 
 poorly adapted amalgam fillings. While amalgam may have been both the patient's 
 and dentist's friend in sa\ing some pretty bad wrecks, >ct like the untrue friend, it 
 
84 PRACTICAL MANUAL OF DENTAL CASTING 
 
 has been the cause of many wrecks. I hope we may be able to eliminate some of 
 these failures with the cast inlay. 
 
 I do not approve of the use of the gold inlay in the anterior teeth, excepting 
 where great stress is brought to bear, as in end to end occlusion, or in opening the 
 bite where abrasion has cut out the lingual surfaces of these teeth. 
 
 The work is very exacting and tedious, but because it can be done in stages it is 
 not so laborious either to patient or operator as some of the older methods, and as 
 far as my observations go, the end to be obtained is nearer reached than by the older 
 method. 
 
 We are all amateurs yet in the handling of the cast gold inlay, and finding out 
 every day that there are things yet to be learned which our conceit had attempted 
 to make us believe we knew all about. 
 
 CAVITY FORMATION 
 
 The first step as with all inlay work is cavity formation, which, as I have said, 
 calls forth all the skill and ingenuity that the best operators possess, if it is properly 
 done. The plan of the cavity should first be mentally mapped out and then executed, 
 if it takes the entire time for one sitting, because upon the proper and perfect forming 
 of the cavity depends the success of the inlay. With the gold inlay it does not re- 
 quire the sacrificing of as much sound tooth structure as it may for the porcelain. 
 
 Force and direction of occlusion must be taken into consideration and the inlay 
 set so that these forces have a tendency of forcing it into the cavity instead of out 
 and away from it. 
 
 We must obliterate all undercuts that the wax may be drawn from the cavity 
 without the slightest change of form. By slightly diverging walls, angles and 
 beveled grooves, get all the frictional retention j'ou can. 
 
 If possible to get, form your cavities wedge shape with flat base or bases bevel, 
 converging towards the pulp. 
 
 The pulpal wall should be as parallel as possible to the surface of the tooth upon 
 which the cavity is located. Saucer shaped cavities, with the dependence almost 
 entirely upon the cement, will fail to hold an inlay for any great length of time, no 
 matter how much time or work you may have put upon the inlay itself. Many 
 discouraging failures in inlay work, I believe, are due to a lack of knowledge or dis- 
 regard for these principles. 
 
 THE WAX INLAY 
 
 The next step is the wax inlay. I believe in taking a good generous piece of 
 the prepared wax, for the reason that small portions are difficult to unite after they 
 have been once moistened in the mouth. Soften the wax in warm water, not above 
 138 F. Do not apply dry heat as it seems to make the wax crumbly. Now press wax 
 to place in the cavity, see that it presses closely to the bottom and over all the 
 borders, then have the patient close the teeth and go through all the movements of 
 mastication, as just the mere fact of shutting the teeth together does not give us 
 correct occlusion. 
 
 The cavity needs no other lubricant than the existing moisture of the mouth. 
 
 After getting the correct occlusion of the teeth, I begin carving away surplus 
 wax and also with flat burnisher work the wax down perfectly to and over all borders. 
 Asking the patient to open the mouth, I hold the wax in place and carve and shape 
 contours; then by means of cotton pledgets and tape moistened with liquid vaseline, 
 I finish and polish this wax inlay until it is just as near my idea of what I desire in 
 
THE CAST GOLD INLAY 85 
 
 the gold as I can get it. Very often I lift it from the cavity, chill in cold water, trim 
 away feather edges and reset in cavity two or three times before I have it completely 
 finished down. When I consider my wax inlay complete I remove and attach my 
 little sprue wire. I prefer doing it this way to attaching sprue to wax in the cavity. 
 Next, adjust sprue to the little crucible former and proceed to invest. This is another 
 portion of the technique which is very critical and wherein your success hangs in 
 the balance. 
 
 INVESTMENT 
 
 Your investment must be of such material in which the shrinkage and expansion 
 shall be the minimum and not change form whatsoever under heat. It needs to 
 be carefully and uniformly mixed and I have the habit of turning my plaster bowl on 
 its sides and revolving while mixing until my investment is coated all over the 
 inside of the bowl in a thin layer — thus allowing escape of any small air bubbles. 
 Now, I prefer a small spatula to place the investment about the wax inlay, forcing a 
 little investment ahead of the spatula and thus driving the air ahead and out of the 
 corners and depressions in the wax. I build up investment about the wax until it 
 is a thickness of probably a quarter of an inch all around. Now I place investment 
 over all the inside wall of the flask and set by a twisting or rotating movement onto 
 the crucible former and carefully proceed to fill it full with remainder of investment, 
 not jarring it, as I wish not to liberate any of the amount of air still contained in the 
 investment and by so jarring it would gather together this air and is very liable to 
 collect on the wax model in little air bubbles, which, when your cast comes forth, 
 you discover as little fine nodules of gold, which you wish were not there as it inter- 
 feres with its being a perfect reproduction of your wax. 
 
 Now give the investment from fifteen to thirty minutes to set before applying 
 slow heat to dry it out. When all moisture is gone and the wax has been absorbed 
 and vaporized, place in machine, melt pellet of gold and cast. I aim to have the 
 pellet of gold about three times the bulk of the inlay. The heat for melting the gold 
 should be very intense and concentrated as with the nitrous oxide flame or the electric 
 arc, as the gold should be in as fluid a state as mercury. 
 
 CASTING 
 
 The casting may be done by any of the machines now on the market, pnn-iding 
 \ou can get absolute accurac}'. 
 
 In experimenting with the different grades of gold to obser\'c the contraction, 
 1 can but recommend that when you desire absolutel>- the best results, you must use 
 pure gold. Dr. Price, of Cleveland, has done some very fine research work along 
 this line, demonstrating both expansion and contraction of gold and its alloys, also 
 expansion and contraction of our present investment materials, which you will find 
 in the May, 1908, number of the Items of Interest. You may cast your inlay with the 
 lower K. golds and get a result which to the operator who is not scrupulously observ- 
 ing might seem to be good, but when you examine for an absolutely perfect adaptation 
 you find it deficient somewhere, owing to the contraction of the metal. 
 
 The casting of the hollow inlay has appealed to me because I always looked 
 upon the hollow matrix inlay with favor, and employed it wherever the case per- 
 mitted me to do so, consequently when taking up the casting I began trying different 
 ideas to obtain the hollow cast inlay. The best method I have found, up to date, is 
 a little copper bulb with a handle attached to one side of it and a small point a little 
 larger than a needle attached to the other side, which is wrapped with absorbent 
 
86 PRACTICAL MANUAL OF DENTAL CASTING 
 
 cotton or fibre asbestos; then by heating the bulb hot, enough heat passes into the 
 point so that by touching the wax inlay where I desire the hollow part, the point 
 will melt the wax and the absorbent draw the melted wax away, leaving just as much 
 of a hollow portion as you desire. 
 
 The hollow inlay gives us a larger layer of cement just over the pulp and insulates 
 it from the metal body and eliminates the thermal shock, as where we desire this 
 inlay we usually have cavities which are in just such a location as to be particularly 
 sensitive. They also give us more attachment for the cement which serves to in- 
 crease the value of retention. 
 
 CEMENTING AND FINISHING 
 
 When our inlay has been formed and tried to the cavity and found to be per- 
 fectly satisfactory, set it with a very fine grained inlay cement and burnish all 
 borders and polish, and if you are like me, you will at this time think of our grand 
 old Professor Watling, when he said, in polishing the gold filling, give it the polish 
 of the inside of your watch case. 
 
 SUMMARY 
 
 In summing up, let me say, first, make a study of the conditions, with your 
 patient's benefits uppermost in your mind; use the cast inlay if in your judgment 
 the restoration will be the very best that can be done by any known method; if not, 
 then use that which will give such a result. 
 
 Do not insert the inlay until you are master of the cavity formation and know, 
 absolutely know, that the cavity formed will hold it. Know that your wax inlay 
 is as near perfect as you can mold it and get an absolute duplicate in the gold. Do 
 not insert an imperfect inlay because you dislike to do it over again. Be a man and 
 take the bitter with the sweet. Your patient will appreciate your interest in having 
 your work right, but will despise you when she discovers you have deceived her by 
 accepting your fee for a defective operation. 
 
 The measure of success we are to meet with lies in direct proportion to the care 
 which we use in the preparation of our work. It is true to the same extent as with 
 any other class of work; a man's individuality, his honesty of purpose, his character, 
 his appreciative sense of his position in his chosen profession towards his services to 
 humanity, are all distinctly shown. 
 
 If the operator is not willing to give time and study and research work in ex- 
 perimenting to bring this method under his control that he may better his services 
 to his patients, I would advise him to let it alone. If the same operator is still 
 unwilling to better his services to his patients along even the older methods at hand 
 and still persists in staying in the same old rut at this day, it would be just as well for 
 his patients if Divine Providence should conclude that his services were better needed 
 in other fields. 
 
 That which I have desired most to impress upon you is thoroughness. 
 
 The dentist who is of the greatest value in his community is the one who is 
 ever alert to every progressive step that will in any way benefit his patient. Such 
 a man is elevating his profession, is making the best of the talents which have been 
 given him, and lastly, doing the greatest amount of good for himself. 
 
 DISCUSSION 
 
 Dr. L. E. Custkr, Dayton, O.: I cannot to any extent disagree with any of the points that have 
 been brought out in this most kindly and exxellent paper by Dr. Lyons, but rather wish to confirm 
 some of the statements wliich he has made. I wish at the outset to pay a few words of tribute to 
 
THE CAST GOLD I NLA Y 87 
 
 Dr. Taggart. We are prone to think of the cast inlay, or the invention of Dr. Taggart, as one not 
 meriting what has already been said of it, because of its extreme simplicity. When a novice looks at 
 a complicated machine, with all the levers, springs and wheels, he stands back in amazement and says 
 to himself, "What a genius that man must have been who invented that." However, when a genius 
 takes hold of such an appliance as that and has reduced the large number of springs, levers and wheels 
 to a small number, to perform the same function, and has simplified an extremely complicated 
 machine, to the thoughtful person that is the machine in which genius is displayed. The simpler 
 machines are those in which the greater exercise of judgment and of patience has been used. And so 
 I would say of the invention of Dr. Taggart, that we are prone, I think, not to give it the full measure 
 of credit which is due this invention, because of its extreme simplicity — a simplicity which in the year 
 and a half since its introduction has been the means of placing upon the market possibly fifty different 
 methods of doing essentially the same thing; I say, it is such a simple thing at this date that we are 
 liable not to give the full measure of credit to the man who worked out and who simplified this process. 
 
 Coming now to the paper, in speaking of cavity preparation, I think that we have had enough 
 experience with inlays, both porcelain and gold, to know that the adhesive property of the cement is 
 not the most effective thing in holding the filling in the cavity; that in just the proportion as we are able 
 to so form the cavity that the filling will be held mechanically, keeping in mind the direction of stress 
 of mastication, will the filling be retained, and it is a mistake on the part of any one beginning this 
 work, who has not made inlays of either gold or porcelain, to trust much to the retentive property 
 of the cement. We must, in some manner or other, form a dove-tail, and that can be done at the same 
 time and the filling can be so shaped that it can be introduced as one plug of metal or porcelain. 
 
 The essayist spoke of inlays for the anterior teeth, and did not place much importance upon the 
 value of cast inlays in this part of the mouth. I think that here is just as important a place as any 
 other, and especially on the corner of an incisor where porcelain, by reason of its brittle characteristics, 
 of which you are all familiar, cannot withstand the stress; here I believe that the Taggart inlay is the 
 thing, but I would call to your attention the value of platinum combinations with gold, when the 
 filling is used in this position. Platinum melts at about .3600 Fahrenheit, and you know that there 
 are only two means by which that can be melted at present, the oxy-hydrogen blow-pipe and the 
 electric arc. With the oxy-hydrogen we have enough heat to melt it in small quantities, but with the 
 arc light we have 6,000 degrees of heat at our command and with this device it is possible to fuse pure 
 platinum with proper investment material. We may make a pure platinum filling in this manner; 
 however, it would call more especially for proper investment than for anything else, for withstanding 
 so high a heat at the time of casting it would be better if we were to^dd some gold to the platinum — 
 about three-fourths of gold and one-fourth platinum. It does not materially affect the color. I 
 think the color is better than with pure platinum, so I would suggest the use of platinum and gold cast 
 fillings for the incisors and any conspicuous fillings for the incisor corners and the anterior proximal 
 bicuspid. 
 
 The doctor suggests the warming of the inlay and the wax impression material in water. I have 
 felt from the first that the forming of it on a stick with a little sharpened point, and that heated over 
 a flame to bring it to the right degree of softness, will give you a better impression of the cavity, because 
 of the fact that the surface is quite soft and it is forced in every detail and line of the cavity on the in- 
 side by the harder material back of that. I rather lean towards that method of obtaining the impres- 
 sion of the cavity. 
 
 The doctor pays much attention to the wax filling. I think that this is just the thing to do. be- 
 cause at this stage, a few moments spent in the proper shaping and dressing of the wax fillings is time 
 well spent and will save you much more time when it comes to the setting of the filling. I prefer to 
 do this also for another reason, and that is that it is easier at the time of setting to burnish and thin 
 the edge in closer apposition to the margin than it is in the unfinished or heavy margin of your filling. 
 You have thus two advantages of dressing the wa.x beforehand, or if you fail to do that, trace your 
 filling and get a close fit with the margin before setting. 
 
 In removing the wax filling I have always liked to warm the end of the sprue wire and imbedding 
 that in the inlay it serves as a handle by which the filling can be easily removed. At the time of taking 
 the wax out of the cavity you can feel whether or not you have prepared your cavity so that it can be 
 properly drawn out, and if you have in any place a slight undercut, of course the enlarged part can 
 be readily rubbed down so that it can be lifted from the cavity to be .set again, then going over the mar- 
 gins for the last time. I have always been better satisfied with the melting in of the sprue wire than 
 drawing or lifting the filling out of the cavitj' by the other method. 
 
 I think in our gold fillings we should use pure gold, because of the fact that it can be easily and 
 readily burnished to fit the cavity margins. Never use a lower karat. 
 
 In addition to the notes which I have taken on the paper I would like to make a few suggestions 
 which have come about through my own experience. Once in a great while an inlay will be made 
 
88 PRACTICAL MANUAL OF DENTAL CASTING 
 
 that has not been sharply cast; it fits the cavity to the very corners but its margins are rounded instead 
 of sharp. This being the case, it is an easy matter, if the margins are excessive, to set that filling and 
 immediately afterwards go over the margins, turning an old carborundum wheel which has been filled 
 with the grindings of gold, revolving that towards the margin, and you can push up the pure gold or 
 flow it ahead of the wheel until you have a perfect adaptation. This can be done where the corners 
 have not been filled out entirely. There are many faulty margins that can be made absolutely good 
 in that way. If the filling is dry and the carborundum wheel is dry it is wonderful to what extent you 
 can push the gold towards the margin by reason of the wonderful cohesiveness characteristic of pure 
 gold. 
 
 Another point is this. In the proximal fillings there will always be noticed a point of contact 
 with the neighboring teeth which is a little flat place right at that point. You can take a bit of 22 
 karat gold, about the size of a pin head, melt it on there, round it out, and it gives a rounded contact 
 surface, to one which is usually either flat or concave. Sometimes these fillings are so well and closely 
 adapted to the cavity that in a quite frail tooth you may chip off a little margin of the enamel. You 
 need not make a new fiUing in this case. Heat the filling to redness under the blow-pipe and let 
 cool without water, and place in the cavity a little bit of platinum and gold foil, or inlay platinum 
 matrix material should be placed over the break. When the foil has been annealed it will cohere to 
 the gold filling, and it can be formed in a moment to the enamel margin, and the filling may be removed 
 and this little cup-shaped cavity can then be filled full of 22 gauge gold, and your filling will be as 
 good as ever. 
 
 Dr. IVIuiR, Detroit, Mich.: I want to congratulate Dr. Lyons upon his paper this evening. 
 When I first started making gold inlays, I had lots of failures, and was just about totally disgusted 
 with gold inlays, but now I have very good success. The dentists who use gold foil, and have always 
 used it, cannot be blamed for not wanting to take to the gold inlay, but there are comparatively very 
 few good gold fillings inserted. There is so much in favor of the gold inlay that I think every man should 
 have an adequate inlay machine for making them. They must be used with discretion, of course. 
 Those enthusiasts who have used porcelain indiscriminately, have some regrets, but it does not follow 
 that everybody is going to take up the gold inlay and use it where it should not be used. 
 
 Dr. Taggart's paper, I think it was in the December issue of the Denial Register, gives a very 
 concise and accurate method of each step of making the wax model. I got more from that than from 
 anything that I ever read on the, subject. The cavity must be prepared properly, and I like to heat 
 the wax in water. Dry heat is all right if you do it properly, if you get it just exactly right, it will 
 be all right, but it is easier to get it exactly right in water, and the water, of course, must be of the right 
 temperature. After pressing wax into the cavity have the patient bite and cool it with a stream of 
 cold water. Trim it off, and then smooth it with Three-in-One oil. There is something in that oil 
 that dissolves the surface of the wax and gives you a perfectly smooth surface. In approximal cavities, 
 use tape; put some Three-in-One oil on it, and run it in between the teeth, and it will give you a per- 
 fectly smooth surface there. Remove the inlay by the use of a fine copper sprue wire; heat it over the 
 alcohol lamp, or gas; insert it into the filling with the right hand, holding in the left hand the water 
 syringe filled with cold water, and when the sprue wire goes into the inlay, put stream of cold water 
 on it. Remove the inlay by grasping wire with pliers. If it comes out hard, put it back again. If 
 there is a slight undercut, it will burnish down. Before you take it out the last time, see that the 
 margins are all right. After it is out, add a small drop of wax from spatula for contact point. Now 
 take care in mixing your investment compound. Do not attempt to make gold inlays with a poor 
 machine and with a poor investing compound. You must have good material to get good results. Care- 
 fully mix your investment compound. I mix it in a saucer. Don't get it too thick; spread it thoroughly 
 over the saucer making a thin layer, and shake it well and blow onit, making the bubbles disappear that 
 rise to the surface. They can be avoided by carefully mixing investment compound and applying same 
 to the inlay with a camel's hair brush. After you have your inlay invested, take care of that. I learned 
 this afternoon that men have had a lot of failures due to careless drying out You cannot hurry your 
 investment in drying. I set it aside for an hour after mixing, and let it thoroughly harden. Then 
 put it on a slow Bunsen burner or in an oven, something of uniform, steady heat, and gradually increase 
 that heat, and I like to leave it there an hour until the moisture is well out of the investment compound, 
 and there is no steam coming from it. Then you can give it as much heat as you like. If you attempt 
 to melt your wax before the moisture is out of the plaster, the wax will bubble out of the cavity, and 
 then you have a rough sediment on the inside of your cavity, and this spoils the inlay. In heating 
 your investment, don't get your investment too hot. It is not necessary to get it hot enough to melt 
 your cup; just get it hot enough to melt the wax. It will smoke a little while and your investment 
 will be black. Apply blow-pipe until the bluish colored flame has entirely disappeared, and possibly 
 
THE CAST GOLD I NLA Y 89 
 
 a little longer. It is only necessary to burn out all the wax, and further heating does not do the invest- 
 ment any good. You cannot get satisfactory results for an inlay with any other gold but pure gold. 
 22 karat will not do. I like to try the inlay in, as soon as I have it cast, and cut the sprue otf. If it 
 goes to its place nicely, take it out and polish it with sand paper disc, and with the grinding surface of 
 a molar, you will have to cut down in there probably with a fine bur — a very small plug finishing bur 
 or a No. !^ or a No. 1 bur for the fissures. A dull one does the work very nicely; and then burnish. 
 Put the inlay in the cavity, and before setting, thoroughly burnish it around the margin. I do not like 
 to burnish after setting. You must burnish before the cement thoroughly sets. Unless it fits into a 
 wedge-shaped cavity very tightly, you are liable to move it, and if you burnish it before cementing, 
 you do not have very much, if any, burnishing to do after. Polish it with sand paper discs, or fine 
 stones rotated on the margins from the inlay towards the tooth. Finish with pumice. 
 
 Dr. W. L. Williams, Sault Ste. Marie: I have had very little experience in cast gold inlays, and 
 I am here to learn, and I think we ought all to honor the pioneers of this work. It is those men whose 
 names will go down in history, and as I am not a pioneer. I honor the gentleman who read the paper, 
 and my friend, Dr. Custer, and will beg to be excused from saying anything more. 
 
 Dr. Travis, Plymouth: The paper has been so ably written and so well discussed up to the 
 present time that while there may be a great deal that could be said upon this subject, yet, it seems 
 to me, that there is very little that we could say tonight that would add very much to what has already 
 been said. However, we all know that the gold inlay of the cast variety has been a blessing to the 
 profession and to our patients, and that it will be received by both alike as a blessing. We know, too, 
 that it possesses qualities that no other filling possesses. We obtain by this method a strengthening 
 of the walls, and a more perfect sealing of the cavity, and at the same time we obtain a non-conductor. 
 There are a great many cavities that we have to deal with where it would not be wise for us to use the 
 gold inlay; however, up to the present time there seems to be nothing equal to it in other cavities, and 
 it seems that a great many of us are led at this time to use the gold inlay in cases where it is not in- 
 dicated. C. N. Johnson, who has been one of the greatest advocates of the gold foil filling, is now one 
 of the strongest advocates of the gold inlay, and yet he has said that if the inlay had been used for 
 forty years or more as the foil filling has been, and we were now to introduce the foil filling, that we 
 would be just as likely to go into ecstasy over the use of the foil filling as we are now over the inlay. 
 The methods of producing this inlay by various instruments is something that 1 am not very familiar 
 with, but in the clinics that I have witnessed it appears to me that a great many, in demonstrating this, 
 have been satisfied by submitting to us samples that are a long ways from perfect, and they always do 
 that with the apology that this is merely a clinic and that it has been done hastily; that it approxi- 
 mately fills the cavity, and that you see the principle, and now if you will only give it time that you 
 can produce perfect results and get perfect borders; but only in very few cases we find that they can 
 with uniformity get these perfect borders. I believe, as a member of the profession — and most of us 
 believe the same way — that it is not the price of the instrument with which we are to attain these 
 results that determines our choice, but rather that we may be positive that with this instrument we 
 shall be able, uniformly, to secure perfect borders. What I mean by perfect borders would be a border 
 sufficiently perfect that we could burnish over and get a perfectly tight border, and protect the cement 
 so that none could tell it from the gold foil filling. 
 
 Dr. J. W. Lyons: The discussion of the paper has not been agreeable to me in a way I would 
 like to have it. In preparing this paper I hoped to get a great many pointers myself in the discussion 
 of it, from other men, because I feel that there are many things yet to be learned about the cast inlay; 
 it is not nearly perfect, by any means, and there are a great many things to be developed yet. 
 
 Dr. Custer thought I did not lay stress enough upon the use of the cast inlay in the anterior teeth. 
 I do not like to use the gold if we can get away from it wherever it is possible to use porcelain, and 
 I think it is possible by proper methods. I like to see the porcelain inlay used in the anterior teeth, 
 but where great stress is brought to bear upon it, and where it is impossible to hold it, then I would 
 resort to the gold inlay, because, without regard to my own feelings as to ideal methods, in my own 
 mind I feel that the patient's benefits are the first thing to be considered. Durability has much to 
 do with the building up of a practice and the building up of your reputation. If you insert fillings 
 or inlays and they have to be restored in a very short time, you lose the respect of your patient; you 
 cannot hope to hold the respect of your patients in having work fail; although you may desire to have 
 a porcelain stay in place, thinking that it is much more esthetic than the unsightly gold, yet your 
 patient will think more of you if your work stands. 
 
 I thank Dr. Custer very much for the added suggestions that he has given us, and the gentleman 
 here on my right, because I know from his talk that he has been up against a great many of the same 
 things that I have been. 
 
90 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 A SOLDERING DEVICE 
 
 By Dr. T. B. MaGill, Kansas City, Mo. 
 
 Screw the flexible arm on to the crown foot, then screw on the clamp-pliers; 
 open pliers and insert the iron spoon (one or more). The pin in the pliers to go 
 through the holes in the spoons. 
 
 Now any soldering which has to be invested can be invested in the bowl of the 
 spoon. (Crown or Bridge.) Coarse investment is better as it is not so apt to blow 
 up by heating too rapidly. 
 
 A soldering device, bv T. B. MaGill 
 
 After case is invested the flexible arm can be adjusted high above a Bunsen 
 flame and as it heats up bend down into flame. Use a very small amount of invest- 
 ment, a film 1-16 in. thick is plenty, the spoon holds it in shape, also distributes heat 
 evenly. 
 
 To solder, place an empty spoon in pliers with one holding invested case. Place 
 the solder in empty spoon. Another spoon may be adjusted for another karat 
 solder or flux. Apply heat from beneath until case is cherry red, then apply solder 
 and flame. By using flexible arm you can get to any part of investment with 
 blow-pipe. 
 
CASTING: A RETROSPECT 
 
 By Dr. J. G. Lane, Philadelphia 
 
 When it first became known that certain areas in Alaska wcie rich in gold, 
 ravenous prospectors and claim-stakers jostled with and fought each other in their 
 mad rush over the coveted territory. This proceeding was carried on amid such a 
 degree of excitement, — each person fearing that each and every other person might 
 find something better than he himself — that the entire field was sort of wallowed 
 over, and worked coo superficially to find out what conditions really did exist. After 
 the place was thus imperfectly worked out in the first spasm of excitement, the same 
 ground was again covered in a manner that was sane and sensible enough to unearth 
 the real value of the environment. These same conditions obtain in our profession 
 as often as new or novel procedures and methods are sprung upon us. And the more 
 unique and novel the innovation, the more this condition obtains. In this particular, 
 casting has been an exception only in that it has been the most extreme case of this 
 kind that has ever come within our observation. And now that the first grand rush 
 for supremacy and record is on the wane, it is high time that we begin to look back 
 over the field, take a retrospect view of what has been done, the theories and methods 
 advanced, and to sift the real wheat from the chaff. This sifting and winnowing is 
 likely to send many pet theories and ideas to the wind — never to return; and indeed 
 wisely so. The dental journals, — aye, and even textbooks on the subject in question, 
 — tell us all manner of theory and methods in the art; many of these are so un- 
 reasonable, fallacious and unscientific in their very aspect, that we cannot but assume 
 that the exponent of such has in all probability arrived at his conclusion theoretically, 
 rather than scientifically or clinically. While we know that the profession as a whole 
 has been wondrously benefited by the result of all this effort, yet we cannot believe 
 other than that many things which have been written and said on this subject from 
 time to time, have proved to be an injury to the cause rather than a help. 
 
 Quoting Dr. C. S. Van Horn, Dental Cosmos, Vol. LI, p. 549: — "At present our 
 work in this field is largely empirical; we have not practised casting sufficiently long 
 to have established it on a scientific basis; consequently we are too many times 
 between the devil and the azure brine to know the how and the why. Some day 
 the clouds will roll away." And in accordance with this thought, we think it high 
 time that some of the overhanging clouds should roll. 
 
 The purpose of this paper, therefore, will be to point out some of the 
 extremely opposite views that have been taken by various experimenters, who, 
 by experiments conducted technically, theoretically, scientifically, and clinically, 
 have endeavored to reduce the art of casting to a true and proper basis. 
 
 Let us consider the impression method for inlay work as advocated by Dr. 
 Weston A. Price, Items of Interest, Vol. XXX, p, 3G3 and 938, and by various other inlay 
 workers. This method has adherents both in the clinic and in literature; the usual 
 arguments advanced in its favor being the lessened possibility of distortion of an 
 impression as compared to a possibility of the same in a finished pattern 
 while being removed from the teeth or cavit\'; time saved at the chair and 
 less annoyance to the patient. Let us quote your essayist from the Dental 
 
92 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Dzge^/, Vol. XV, p.436 — "The pattern for a gold inlay should be made in the cavity 
 that is to receive the finished casting. This insures a better adaptation than 
 can be had by any method thus far devised for making the pattern in a model. 
 In the former method we have three transfers — cavity to pattern, pattern to in- 
 vestment, and investment to gold. In the latter we have five transfers — cavity 
 to impression, impression to model, model to pattern, pattern to investment, and 
 investment to gold; or, if the casting is done directly in the model we still have 
 four transfers by the latter method. In any transfer we can scarcely' avoid losing 
 detail and definition; therefore, the fewer the transfers the better the inlay is 
 going to fit, — all other things being equal. Furthermore, there is vastly more pos- 
 sibility of distortion in an impression than in a pattern. This can easilj' be under- 
 stood when we consider that the pattern is adapted to the interior of the cavity only; 
 while an impression for a model is adapted not only to the interior of the cavity but 
 also to the exterior of the tooth — as well as to adjoining teeth. Removal of such an 
 impression from the tooth or teeth is almost sure to distort it; nor is there by this 
 method any possibility of determining whether distortion is present or not until the 
 inlay is made, i^y the direct method there is very little possibility of distortion; 
 or if there is a suspicion that distortion is present, it can easily be proven and corrected 
 before proceeding further." Instead of the impression method amounting to a saving 
 of time in the chair, we believe it to take more time than the pattern method, because 
 of the fact that two operations — one for impression and another for bite — are 
 necessary. And if, therefore, as much time is consumed, the patient has not re- 
 ceived the benefit of any spared annoyance. If, as is advocated by some, the 
 model for such a case is to be made of amalgam, and the wax pattern for the inlay 
 then made in the amalgam model, we at once find that the time consumed after the 
 impression and bite have been taken, is very prohibitory — in addition to the almost 
 certain result of inaccuracy on account of too many transfers, and the possibility of 
 distortion. It is, therefore, patent to all that the method which will insure the 
 greatest accuracy of adaptation is the one which is most desirable to follow. 
 
 We believe that the more general use of inlays has done much toward educating 
 the profession in general to appreciate a higher standard of cavity preparation. 
 As to fundamental conditions which should obtain in this part of the work, all seem 
 to be pretty nearly a unit. In detail, however, there are wide differences. Let us 
 quote Dr. P. B. McCoullough, Dental Cosmos, Vol. LI, p. 1175: — "No filling material 
 has at its square edge the strength of the square edge of enamel. The beveling of 
 enamel margins for protection is illogical when the weaker body is to provide the 
 protection." Let us also quote Dr. Theodore C. Trigger, "Notes and Methods of 
 Filling Teeth with Gold Inlays," p. 46 — "The marginal edges of the cavity should be 
 cut straight and beveling avoided." The authority quoted repeats this statement 
 on p. 59 of the same publication. Let us also quote your essayist, Dental Cosmos, 
 Vol. LI, p. 434 — "The margin of a gold inlay being thoroughly homogeneous is 
 reliable even at an angle of 65 degrees. This secures for the enamel margin the 
 remarkably strong angle of 115 degrees." This seems to be just about the extreme 
 opposite. However, we feel positive that we have seen our contention in this upheld 
 clinically at all times; and we believe that proper clinical results are most important. 
 For inlay work we disapprove of the extremely angular form of cavity preparation 
 generally known as the "Black Method," and by some inlay workers followed out in 
 cavity preparation for inlays. We believe that the inverted cone and square end 
 fissure burs have no place in the equipment for inlay cavity preparation. Quoting 
 
CASTING: A RETROSPECT 93 
 
 again from your essayist, Dental Cosmos, Vol. LI, p. 433: — "Sharp angles at the 
 cervico-buccal and lingual aspects of an approximo-occlusal cavity have no point of 
 merit whatever, and serve only to weaken the tooth as a whole." Also quoting Dr. 
 Trigger from the publication mentioned above, p. 59: — "The enamel walls should 
 not terminate too abruptly in short curvatures." P. 60: — "No definite angles are 
 used in the preparation of cavities for inlays." And further down the page, "At the 
 junction of the gingivo-labial and buccal surfaces the cavity should be cut in a rounded 
 form." Dr. Trigger then goes on to state the advisability, and almost necessity, 
 of sharp angular forms in these parts of cavity preparation for gold foil fillings. 
 
 Sharp angles at the points mentioned in the quotation of your essayist, have 
 the effect of confining the area of possible fracture to one point, while if these parts 
 of the cavity have a very slightly rounding effect the area of possible fracture is 
 distributed over the area thus filled in, and no one point will have to endure the 
 encire violence, e. g., a steel bar 3 inches in diameter, having a point at its 
 center cut down by a narrow sharp edged groove to 1 inch diameter will 
 fracture more readily under load than if the entire bar (or even a longer 
 distance in its center) were only 1 inch diameter. If there are sharp angles pointing 
 outward from the interior of a cavity there will be similar angles in a casting mould; 
 these are likely to receive slight abrasion and injury when the gold is cast past and 
 against them, thus causing a misfit. The more angular the cavity the more diffi- 
 culty is experienced in getting the inlay properly seated; the surplus cement must fol- 
 low a more tortuous line to escape. We cannot see that sharp internal angles add 
 in any way whatever to the degree of stability or fixation of an inlaj- after it is cement- 
 ed in position; nor can we see how such could in any possible manner strengthen the 
 operation and tooth as a whole. Furthermore, there is a possible element of inac- 
 curacy of adaptation to sharp angles in making the wax pattern. 
 
 Much diversity of opinion exists in regard to the temperature the mould should 
 have at the moment of casting. Quoting Dr. Marcus L. Ward, Dental Cosmos, Vol. 
 LI, p. 1055: — "We are to cast our gold into moulds w^hich have been heated suffi- 
 ciently to eliminate all mechanical moisture and allowed to cool down tilltheycanjust 
 be handled with the hands without discomfort if we are to place the casting of gold 
 on a practical as well as scientific basis*." Quoting also Dr. C. R. Baker, Dental 
 Review, Vol. XXIV, p. 133 — "My first conclusion is, — that the only way to cast 
 inlays is in a cold mould. . . . With a cold mould we get a better specific gravity." 
 Quoting also your essayist. Dental Digest, Vol. XV, p. 499 — "If the flask contains a 
 mould of an inlay for a double compound cavity, or one that encircles or sits astride 
 some portion of the tooth, it should be exceedingly hot at the moment of casting. 
 This will give the minimum of shrinkage with a given investment." And on the 
 following page — "For inlays representing simple interiors, the flask need not be 
 so hot as for the classes just described; but it must always be borne in mind that the 
 lower the temperature of the flask the greater the shrinkage, and that the approxi- 
 mate amount of shrinkage desired shall determine the reduction of temperature in 
 the flask at the time of casting." 
 
 Dr. Ward, in the publication quoted, does not seem to give any very definite 
 reason for his belief regarding the temperature of the mould. Dr. Baker states his 
 reason as being that a better specific gravity is obtained. We cannot see that Dr. 
 Baker's figures for shrinkage (or expansion) in the publication quoted (pp. 130 and 
 
 *We are not informed as to just what this scientific basis is. 
 
94 PRACTICAL MANUAL OF DENTAL CASTING 
 
 131), mean very much unless the size of the pattern for each was given. On the 
 following page we may read: — "The average size of the wax cubes is .1995 in." 
 Unless the patterns had an absolutely uniform and stated size the table would not 
 show much, except hy computation if the size of the pattern for each experiment 
 was given. The sizes are not given except as above. Experiment No. 3, Table III, 
 reads: — "5 dwt. hot .2000, 18.308 Pecks," and conveys to us the information that 
 5 dwt. of pure gold was cast into a hot mould of Peck's investment, and that the 
 resultant casting measured .2000 in. and had a specific gravity of 18.308. No figures 
 are given for the size of the pattern for this particular casting. But if the flasked 
 pattern was .1995 in. we believe that the result as stated is a physical impossibility 
 so far as it pertains to the size of the casting. Experiments that we conducted along 
 this same line to determine figures on shrinkage showed Peck's investment to have a 
 very decided degree of contraction on being heated to a high temperature. Our 
 figures for the particular experiment that might be placed in comparison with the 
 above are these: — size of pattern .5000 in. (half an inch); temperature of mould, — 
 red heat; size of casting, — .4957 in.; investment. Peck's. This shows a loss of .0043 
 in. in a casting made in a mould as hoc as the fusing point of the brass flask that con- 
 tained the mould would safely allow. In eleven of the twenty-eight experiments 
 of Dr. Baker we are given figures which show castings larger than the pattern (.1995 
 in.) anywhere up to .2030 in. — or in one instance an increase of .0035 in., and this 
 in a vacuum machine. Two of the tables given are the data for vacuum machines. 
 The make of vacuum machine is not given, but we assume that it has iron flasks. 
 Iron has an expansion equal to about one-half the expansion of gold; and in order 
 to expand enough to give a casting the size of a given flasked pattern would have to 
 be heated to double the fusing temperature of gold. Of course, the investment would 
 not stand this; and granting that it did, the casting would show a register only after 
 the whole had cooled down to 201 B degrees — which register would be only half enough 
 to neutralize the contraction of the gold. In our experiments the best result ob- 
 tained in an iron flask, cast at red heat, gave a casting .4943 in. from a pattern of 
 .5000 in. Two other machines mentioned in the tables are Taggarts and Jamesons. 
 These both have brass flasks. Brass expands a trifle more than gold at a given tem- 
 perature. With these it is possible to get a casting almost the size of the flasked 
 pattern, but absolutely no larger. The highest reading we obtained on castings 
 made in a brass flask, and at a temperature almost sufficient to fuse the flask, was 
 .4992 in. from a pattern of .5000 in. We are strongly of the opinion that Dr. Baker's 
 patterns were not the size he supposed them to be. 
 
 Increased specific gravity is, indeed, a most excellent feature in an inlay. And 
 we do not take issue with anyone's statement that casting in a cold mold increases 
 the specific gravity of the casting thus produced. We have not experimented along 
 this line but we know that this condition obtains in grey iron. Grey iron cast against, 
 or in, "chills," is so finely crystalized and hard that it cannot be cut except by 
 grinding; and cannot be annealed except by remelting. If, however, the increased 
 specific gravity of a gold inlay be obtained at the expense of accuracy, of adaptation 
 — which feature would undoubtedly obtain from shrinkage if cast in a cold mold — 
 we cannot but sec that as a whole an already strong point has been strengthened, 
 and a weak point made weaker. Namely, the density of any gold inlay is more 
 durable than the cement line which surrounds the inlay. Increased specific gravity 
 can be obtained to a sufficient depth on the masticating surface by means of round 
 or corrugated engine burnishers, 
 
CASTING: A RETRCSTECT 95 
 
 Quoting again from Dr. Baker, in the article prex'iously referred to, "If we have 
 a step cavity with a good dovetail in the occlusal we find that that dovetail is going 
 to draw the inlay into position towards the occlusal in such a way that when pressed 
 down or hammered into place in the best possible way there will be at the cervical 
 a heavy line of cement showing. Why is that? It is simply because the cavity is 
 prepared with almost parallel sides, and if this inlay is the same size as the cavity, 
 the cement will take up too much space, so that it raises it." Our observations in 
 such instances have shown that the condition as described is not due to its close 
 fit in the cavity and the interference of cement, but because of excessive contraction 
 of the inlay. When the morsal part of such an inlay is seated on its foundation, 
 the approximal part is not long enough to reach its destination at the cervical aspect 
 of the cavity. Also that the part fitting into the dovetail (if this dovetail be a very 
 pronounced one) is so contracted that it will not allow the approximal part to fit 
 closely against the pulpal wall of the cavity except at the angle of the step. This 
 observation may easily be made, and the facts cited determined, by placing such an 
 inlay in the cavity without cement, and see exactly the condition referred to. 
 
 We believe that the shrinkage problem in cast gold inlays is net generally con- 
 sidered as important as its clinical results will warrant. Quoting from Dr. Ward, 
 Dental Cosmos, Vol. LI, p. 1056: "If, then, a filling 1-4 in. in diameter shrinks 
 .0008 in. and is seated in the center of the cavity, there will be .0004 in. to be filled 
 with cement on each side. If the casting be a compound approximal one for a molar 
 measuring 1-2 in., we can only calculate a total shortening mesio-distally of .0016 in. 
 Imagine, if you will, such a cavity being prepared with its walls inclining sufficiently 
 to enable one to draw a wax impression, and a filling that had shortened from the 
 extreme ends only .0016 in. Do you doubt its going to place? It will do it so clcselj' 
 that the naked eye cannot detect it, if the cavity has been properly prepared. These 
 figures will not hold good for casts made in a red-hot mold, or if the gold is super- 
 heated. They hold good for casts made of gold heated above its melting point, and 
 a little below its boiling point, and cast in a cool mold." Also quoting Dr. Price, 
 Items of Interest, Vol. XXX, p. 933: "In bridge work, because of the length of the 
 piece, the cooling contraction not only makes the piece too short to reach the abut- 
 ments, thereby throwing one of them out of register, but, if the attachment encloses 
 a foundation as a ferrule for a root, its decreased diameter will not allow it to go over." 
 In Dental Cosmos, Vol. L, p. 940, (Hinman) shows a cut of a bridge with two inlay 
 anchorages. Items of Interest, Vol. XXXI, p. 815 (Reynolds), shows a cut of a 
 similar bridge. Dr. Baker in the article referred to a number of times, says: " 1-10000 
 in. in the size of an inlay larger than the cavity is almost fatal." In the bridges 
 referred to, a shrinkage of 18-100 of one per cent, would put the inlay anchorages so 
 much out of register that they would not seat properly, and possibly not even in- 
 differently. The double compound inlay that registers a shrinkage of .0016 in. — as 
 cited by Dr. Ward in the above quotation — would certainly not go into place unless 
 it was forced into the cavitj' under a pressure sufficient to actually stretch it. This 
 particular kind of inlay is the most difficult we have to make; and one wherein the 
 shrinkage problem looms up most forcibly. For if the inlay is large enough to nicely 
 sit astride the shallower central part of such a cavity without stretching, it would 
 have to be at least as large as the cavity. If such an inlay is absolutely as large 
 as the cavity it will not go in and seat properly for the other dimensions; and par- 
 ticularly so when we reckon the space necessary for the cement line. One dimension 
 of such an inlay ought to be a trifle larger than the pattern; and the other dimension 
 
96 PRACTICAL MANUAL OF DENTAL CASTING 
 
 shorter. This condition wc know would be impossible to obtain; and the only chance 
 for us is to force enough stretch into it to allow it to reach over the interior of such 
 a cavity. 
 
 We are firmly of the opinion that the investment has a very great deal to do 
 with shrinkage, or lack of the same. An investment material should expand suf- 
 ficiently on heating to follow up the expansion of the brass flask which contains it. 
 With such an investment the shrinlcage can easily be taken care of, except in large 
 bridge castings. During the autumn of '07 your essayist conducted a more or less 
 exhaustive series of experiments in an effort to formulate a suitable investment 
 compound. The result of the experiments was given at a regular meeting of the 
 Pennsylvania Association of Dental Surgeons, during the same autumn, and also 
 in a paper read at San Francisco in June, '08: — a record of which is in the Pacific 
 Gazette, Vol. XVI, p. 586. The best results we obtained were gotten in a compound 
 made up of cast plaster 1 part, and very finely powdered silex 3 parts (by weight). 
 In April and May, '09, we conducted a series of experiments to obtain data on 
 shrinkage of gold castings. Castings made in Peck's investment compound si;owed 
 83-100 of one per cent, shrinkage; S. S. White's showed 18-100 of 
 one per cent., and in silex and plaster as above given, we had only 16-100 of one 
 per cent, shrinkage. These figures are for casts made in hot molds. With the same 
 investments and technique, except that the flasks were allowed to cool to a tem- 
 perature which allowed handling with the fingers, we had a loss of 1.64 per cent, by 
 shrinkage in the plaster and silex investment, and proportionately more with the 
 other investments mentioned. 
 
 Quoting from your essayist. Pacific Gazette, Vol. XVI, p. 589: "A smoother 
 casting is obtained if the investment has been allowed to remain some hours, or even 
 days, before heat is applied." While this idea is all right for the purpose stated we 
 find that if a flask is allowed to stand a long time before casting we have a marked 
 increase in the shrinkage of the casting made in such a mold. We, therefore, find it 
 advisable to choose the least evil, and cast within a few hours, at most, after investing. 
 
 We, with others, believe that the time will come when the perfection of casting 
 devices will make it possible for us to pre-determine the amount of shrinkage. 
 Quoting Dr. Baker, Dental Reviezv, Vol. XXIV, p. 130: " I believe that the time will 
 come when we can control the size of the cast we want by the temperature of our in- 
 vestment. When we get this work down to a certain pcint we will need a thermostat 
 to tell the temperature of our investment when we cast in order to get the size we 
 want." Quoting your essayist, Dental Digest, Vol. XV, p. 499: "It yet remains 
 for some genius to devise a form of casting apparatus with a pyrometer attachment 
 to indicate the temperature of the flask while casting; this, in conjunction with an 
 investment material of known physical properties could be a means of accurately 
 determining the relative size of the casting." 
 
 We believe that a misconception is more or less generally extant in regard to 
 why any pressure should be needed to place and hold the molten gold in the mold 
 in casting, the commonly accepted idea being that the pressure used is needed 
 because of air and gases within the mold. Quoting Dr. Trigger, Dental Brief, July, 
 '09, p. 469: "In order to force the molten gold into such a mold already described 
 it requires a pressure exerted on the metal in the molten state to overcome the 
 atmospheric pressure of air within the mold, that is, the force on the gold muse more 
 than equalize the air within to allow it to flow readily to all parts." According to 
 experiments which we conducted we believe that air or gas resistance has so little 
 
CASTING: A RETROSPECT 97 
 
 to do with the need of pressure that it need not be taken into consideration. Quoting 
 your essayist from the Dental Digest, Vol. XV, p. 498: "The only reason why any 
 pressure is needed is that the molecular attraction that holds a mass of molten gold 
 in globular or spheroidal form is greater than the force of gravity; the gold, therefore, 
 will not by force of gravity change its spheroidal form and flow down into a mold 
 without assistance." The experiment which proved this consisted in preparing a 
 flask with investment material in such a manner that the sprue opening extended 
 entirely through the bottom of the investment and flask. The flask was heated to 
 redness — ^as if for casting — placed on a support so arranged that anything that 
 wanted to go through the sprue opening would have no interference from within or 
 underneath, and gold fused in the crucible. There was, indeed, under such conditions 
 no air resistance from within or underneath; but gold fused in the crucible immediately 
 over the sprue did not drop through the opening. Varying amounts of gold were 
 tried: 2, 33^ and 514. dwt. The first sprue opening tried was of standard size for 
 practical work — .055, or a trifle smaller than 15 gauge. The gold was heated 
 by the oxy-hydrogen blow-pipe until volatilization began. If the flask was raised 
 a couple of inches and set down with a jolt the gold would then run through. The 
 size of the sprue opening was increased by known stages until it was .120 in. (almost 
 1-8 of an inch) before the gold would run down of its own accord when melted — 
 and even then only when heated to a temperature quite beyond its fusing point. 
 
 We believe that the margins of an inlay should be thoroughly burnished to the 
 cavity margins as soon as cemented in, and before the cement has become friable. 
 And in order that the burnishing may be effective as a means to an end, the wax 
 pattern must have been prepared without any overlap whatever. If an overlap is 
 present, it is the overlapping part that receives the burnishing, and which is after- 
 ward cut away in the finishing. What is then the edge of the inlay has not been 
 affected by burnishing at all. 
 
 The cementing and finishing of an inlay should be completed at the same sitting, 
 and before the cement has attained its utmost density. We believe that it is possible 
 for the heat caused by the friction of grinding stones to be in some cases sufficient 
 to cause expansion of the parts involved; the inlay having a very different coefficient 
 of expansion from that of the cement and tooth under it may cause some areas to 
 actually break the heterogeneous union. Before the cement has become fully 
 hardened its physical properties would allow for this unequal expansion without risk 
 of fracture. This, purely theoretical, having no data on the subject; but we believe 
 that it is possible for this condition to obtain. As stated earlier in this paper, the 
 desired specific gravity on the surface may be obtained by the generous use of engine 
 burnishers of steel or agate, or still better, of corrugated steel. 
 
 After noting the vast differences of opinion that we have quoted and referred 
 to, we may in our perplexity well wonder, as did Pape in his "Moral Essays" — "Who 
 shall decide when doctors disagree?" 
 
 DISCUSSION 
 
 Dr. E. B. Lodge, Cleveland, O.: I will take this opportunity first to thank tlie program com- 
 mittee for allowing my name to appear in connection with that of our essayist, Dr. Lane. 
 
 The subject is a most timely one and one which must elicit the attention of all dentists desirous 
 of attaining the best results for their patients. In much that the essayist has said I most heartily agree, 
 but there are some things which I cannot indorse. 
 
 Quoting from the essayist's paper, he says, "In any transfer we can scarcely avoid losing detail 
 and definition, therefore the fewer the transfers the better tlie inlay is going to fit, all other things being 
 equal," 
 
98 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Now. there are none who will not agree to this statement, as in it the essayist is perfectly right, 
 but he tells us "the pattern for a gold inlay should be made in the cavity that is to receive the finished 
 casting, that it involves but three transfers, cavity to pattern, pattern to investment, and investment 
 to gold." The model method where, for example, we have an amalgam model, he tells us that we have 
 live transfers, "cavity to impression, impression to model, model to pattern, pattern to investment, 
 and investment to gold," and again to quote, "or if the casting is done directly in the model, we still 
 have four transfers by the latter method." 
 
 Just here I must object; since the model made in the impression becomes a part of the investment, 
 how can it entail another transfer of cavity surfaces than when a wax pattern is invested? Dr. Lane 
 is in error, for each process entails only three transfers of cavity surface. Then, too, in securing the 
 occlusal dimensions the patient can close his teeth upon a piece of softened wax as readily as he can 
 close upon a wax pattern within the cavity. 
 
 Few operators can carve a wax pattern for a compound cavity within the mouth in even ten times 
 the time required to carve a very accurate one upon a stone model of the case, by which method is 
 avoided the almost impossible task of carving exact contours and margins under the gingival tissue in 
 a difficult environment. 
 
 This method obviates also the possibility of the wax pattern lifting up at one side when pressed 
 down upon the opposite side as is so liable to happen in the direct method. I should like to ask further 
 how the essayist would get the needed pressure on his contact point without extra work 
 
 How by the direct method can an operator reproduce several contact points at once or even two 
 adjoining and get them accurate? (Here I show set of models, one showing inlays with five contact 
 points and two double compound cavities.) Just figure the difference in time carving them all up in 
 the cavities and taking one impression of them all in a few seconds. Can any man produce as perfect 
 contours by carvmg in the wet mouth as the finished model shows? All those restorations were inserted 
 together. 
 
 How does the essayist hold the inlay in pohshing? How, in polishing, does he prevent spinning 
 of the margins? How, too, does he prevent the gold from shortening mesio-distally in a double com- 
 pound cavity, and how does he correct for distortion of the cavity surface due to pressure upon the 
 investment? 
 
 And how is he able to differentiate between expansion, distortion of the investment and expansion 
 of the cooling gold or decrease of normal contraction due to pressure e.xerted? 
 
 That a distortion does result from the pressure exerted upon the investment from within at the 
 time of casting is a demonstrable fact. This is overcome by the use of the artificial stone model. Its 
 rigidity enables it to withstand any amount of pressure that may be desired without distortion and con- 
 sequent change of shape of the resulting inlay. 
 
 One point further in the advocacy of the model method, greater accuracy of adaptation is assured, 
 particularly in compound and double compound cavities, by the taking of an impression in a suitable 
 wax and specially adapted tray to hold same, and I believe there is less likelihood of distortion in the 
 removal from the teeth of such a tray with its wax impression than there would be in removing a wax 
 pattern directly from such a cavitj'. 
 
 Dr. Price has shown and I will quote his exact words, "the total contraction of a definite part of 
 cooling mass of any metal or alloy can be materially lessened by the application of pressure to another 
 part of the same coohng mass. This causes most of the contraction to occur in one place where not 
 objectionable. As the contraction takes place the mass is moved by the pressure at a certain point to 
 replace the shrinkage taking place elsewhere, but this can only occur so long as the pressure is greater 
 than the resisting strength of the mass, which for available pressure for our use is only a few hundred 
 degrees." 
 
 "By this means we can with only one-fiftieth of an ounce actual pressure reduce the total con- 
 traction in part of a mass of pure gold from 22.5 thousandths to 20.5 thousandths and with one-tenth 
 ounces reduce it to 18 thousandths. With three pounds we may reduce it to 1-i thousandths and with 
 five and one-half pounds to 13 thousandths. Remember that the actual pressure is not represented by 
 the surface pressure per square inch of a gas pressing upon it." 
 
 To quote still further, "The other methods of correcting this contraction are by modifying the 
 alloy to have a minimum contraction (in which as yet but little has been done but no doubt will be) and 
 by either enlarging the mold so that the cast will be the correct size when contracted, or by holding the 
 metal, compelling it to stretch when cooHng, or both. This can be accomplished by expanding the mold 
 into which the cast will be made, and the latter only where the metal can be confined over a very strong 
 form, as a ring around a very hard core. 
 
 "The expansion of the mold has been accomplished to a certain but not sufficient extent by heating 
 an investment material forming a mold and casting into it when hot. The best of these only allow an 
 expansion by this method of six or eight thousandths, and most investment materials very much less 
 
CASTING: A RETROSPECT 09 
 
 if not an actual contraction on heating and this class of material on heating being chiefly silica and 
 plaster, has so little resistance or strength that it is easily distorted by high pressure, absolutely limiting 
 the use of the first named method for preventing the contraction, viz., by making high pressure on 
 another part of the cooling mass, for they yield producing beads and distortion on the surfaces, which 
 if on the cavity surfaces of the inlay, spoil it. The ideal conditions demand, then, that into the mold 
 into which we cast, all surfaces that are ta make contact with cavity walls and margins be so hard and 
 strong that they will allow of high pressure without yielding and should expand either when heated or 
 setting, or both, to increase its dimensions uniformly about 1.5 thousandths which is one and one-half 
 per cent. 
 
 "When casting upon this with an actual pressure of about two and one-half pounds, we will have 
 a cast within about one thousandth the dimensions of the original." 
 
 Now I might say something about the use of the cold mold, but suffice it to say that with the 
 present investments molds contract on cooling from 5 ten-thousandths to 35 ten-thousandths, according 
 to the investment employed, less than their size prior to heating, which only serves to accentuate the 
 contraction of inlays cast in such a mold. 
 
 I have the opportunity here today to extol this fellow townsman and a most unselfish co-worker in 
 the field of dentistry. Dr. Weston A. Price, a man who, like Dr. Black, was so worthily eulogized at 
 yesterday's session by our fellow member. Dr. Friesell. Just as Dr. Black has brought out of chaos 
 into systematized practice the field of operative dentistry by determining the causes of failure in the 
 filling of teeth and in finding and proclaiming an adequate remedy, so has Dr. Price been an indefatig- 
 able worker in the study of the subject of the gold inlay; not only is he a blazer of trails in this de- 
 partment of operative dentistry, but I am sure you will all agree with me that he towers head and 
 shoulders above the rank and file even of the small minority of the profession who attend dental society 
 meetings. 
 
 Some one has said, "Show me the books a man reads and I will tell you the kind of man he is." 
 We will all agree, I think, that this holds true equally with the kind of friends he selects, and if perchance 
 he be a dentist, even by the kind of instruments he employs. 
 
 1 was once visiting a dentist's office and I happened to see his set of excavators and behold! what 
 a mess of rubbish they were, but not merely that, they were so dull that I questioned whether they had 
 seen an Arkansas stone since they left the manufacturers. I instinctively put that man down as one 
 not to be emulated. 
 
 Now, if good instruments are to be the gauge of excellence, let us. or those of us who have not done 
 so, not only adopt the beautiful instruments of Dr. Black's designing, founded upon experience, with 
 angles and dimensions all scientifically determined with great exactness for the work they are to per- 
 form, but let us also adopt as an instrument for saving teeth, the artificial stone suggested and advocated 
 by Dr. Price. 
 
 Closing remarks of the essayist: 
 
 Mr. Presjdent and Gentlemen: We are exceedingly sorry that train time for our departure is 
 so near at hand that the discussion of the paper under consideration could not be prolonged; there being 
 yet many points upon which we should like to have heard an expression of opinion. The operation of 
 casting is as standard as any of our present day operations, and the problems which it involves merit 
 the most thorough attention and research possible. A comparison of differences of opinion on the 
 subject is — from an educational standpoint — second only to exhaustive scientific experimentation. 
 In order that the result of experiments may obtain as a means to an end, such experiments must be. or 
 have been, conducted along lines that are strictly scientific, and in absolute accord and harmony with 
 such laws of physics as are known to be inflexible. 
 
 Dr. Lodge has indeed given us much material for consideration, and has presented it in true masterly 
 fashion. His discourse is largely in the nature of an interrogation. We welcome the interrogation, 
 and would have preferred it to have included many other points. We have jotted down the various 
 questions asked by Dr. Lodge as well as we could get them in hurried fashion, and if we have failed to 
 get them all will call upon Dr. Lodge to restate such as are not in evidence. 
 
 Dr. Lodge seems to be a firm advocate of the "indirect" or impression method, and takes exception 
 to our statement that by the impression method there are too many transfers. He states that by cast- 
 ing in a model of artificial stone the number of transfers is the same as by the "direct" or pattern 
 method. This is not correct. The little joker which he interposes in saying. "The model made in the 
 impression becomes a part of the investment." almost conceals the truth. Unless it was all of the in- 
 vestment his criticism does not hold good, and the best he can do is three transfers for a part of his 
 wax pattern, and four for the balance of it — as against three transfers throughout by the direct method. 
 The number of transfers by any method is of less consequence than the integrity, or questionability of 
 such transfers, or the possible element of inaccuracy in handling the transfers, and we must still insist 
 that — as stated in the paper — there is vastly more possibility of distortion in an impression than in a 
 
100 PRACTICAL MANUAL OF DENTAL CASTING 
 
 pattern, and for the reasons stated. We all know that a plaster impression is almost invariably broken 
 while being removed from the teeth — even though that impression includes a very small area. Why 
 does it break? Because the shape of the tooth, or teeth, is such that the rigid plaster cannot come off 
 over larger portions of the tooth, or teeth, or follow varying axial lines of the enclosed teeth, without 
 breaking. The same condition that breaks a plaster impression bends a wax or compound one. Grant- 
 ing that the outer surfaces of the teeth and the interproximal spaces are of such shape that an impression 
 would draw without bending or breaking, it yet remains that the prepared cavities in those teeth must 
 have exactly the same line of draught. This latter is a very exceptional condition, and when obtained 
 at all, it is usually an unnecessary expense of tooth structure. 
 
 The models shown by Dr Lodge show beautiful work. Articulation and contact points just right. 
 And the inlays fit the cavities absolutely. Naturally, having been cast therein, and not removed 
 since. But, how can any one here determine by examining these models whether the impressions 
 in which they were made were distorted or not? If this model is accurate, then the impression in which 
 it was made must have been accurate; if the wax impression was accurate then the teeth over which 
 it was taken must have had no contour — or at least could not have been larger at the coronal portion 
 than at the gum line; al) the teeth included must have had their axial lines parallel; all the prepared 
 cavities must have had their lines of draught exactly parallel with each other, and all parallel with the 
 long axes of the teeth. Can we conceive of finding such a condition in ordinary practice more than 
 once or so in a lifetime? And unless the conditions as enumerated are present in a given case, distortion 
 of a wax impression must be expected — even with all the preventive possibilities that the neat little 
 trays can provide. 
 
 Dr. Lodge tells us that a pattern can be made quicker in a model than in a tooth. In some cases 
 this can easily obtain. But when we consider the extra operations — such as taking an impression, 
 taking a bite, making a model and fusing it, placing the model and bite on an articluator — we are then, 
 by the impression method, only ready to begin the same routine of operations that would entirely 
 complete the case by the pattern method. Time is money. Either the patient or the operator must 
 lose by the slower method. 
 
 Dr. Lodge asks how we would get the needed pressure on the contact point. We do this by in- 
 serting the sprue wire at this point. The sprue wire we use for ordinary work is 0.070 in. The extra 
 pressure for the contact point is thus gotten without any extra operation, or apparatus. 
 
 Dr. Lodge also asks how adjoining contact points can be gotten by the direct method. There 
 are various ways. One is — press pattern wax into both cavities; bite, rough trim, and separate the 
 two with a thin ribbon saw; then finish each separately while the other is in position. Place the sprue 
 wire in each at the contact point to get the needed pressure. Another method is — first make one 
 pattern, and while it is in place adjust an oiled matrix to the other cavity, and make the second pattern 
 in it. (An "Ivory" matrix works very well for this.) Place sprue wires as stated. Still another, 
 method is — that one cavity can be completed at a time. 
 
 Dr. Lodge asks how we hold the inlay while polishing. We do not hold it while polishing, having 
 always maintained that the only proper place to polish an inlay is in the tooth after cementation. 
 We do whatever shaping is necessary where the riser is cut off, while holding the inlay in our fingers; 
 using great care to not even approach a margin. An inlay is not ready to be polished until it has been 
 cemented in the cavity, and its margins burnished before the cement has become friable. 
 
 Dr. Lodge also asks how we prevent the gold from shortening mesio-distally. This is accomplished 
 the same as for any other dimension. As stated in the paper, it is easily possible to make a casting 
 in the investment given, that has a shrinkage of only .16 of 1 per cent. Granting that we have a 
 casting that has a zero measurement (no shrinkage), we could not seat it in cement. Cement occupies 
 space. As stated in the paper, one dimension of an inlay for a double compound cavity should be a 
 trifle larger than the cavity, and the other dimension smaller than the cavity. There is as yet no 
 means of bringing about such a condition. The pattern for such an inlay can be cut away from under 
 the center until the resultant casting will stretch enough to allow for what little may be necessary. 
 
 Dr. Ivodge asks how we correct for distortion of the cavity surface due to pressure upon the invest- 
 ment. We obviate the need of any correction by using a definite pressure that does not distort the 
 mold. We cast under a pressure of 25 lbs. (air pressure) per square inch. And having tested our 
 investment up to 45 lbs., we know that we are absolutely safe at the former figure. Furthermore, 
 high pressures are not necessary. The only argument ever advanced in favor of high pressure is that 
 shrinkage can be partly overcome by that means. We have experimented with pressures ranging 
 anywhere from sharp margins (5 lbs. per square inch) to the strength of our investment (45 lbs. per 
 square inch) and in that range, any variation in contraction due to varying pressures could not be 
 detected by a vernier micrometer. Inasmuch as by the artificial stone method a part of the mold is 
 made of ordinary investment material. Dr. Lodge's question would apply to that method as well. 
 Beads on a casting do not indicate a distorted mold. They indicate faulty technique in placing the 
 
CASTING: A RETROSPECT lOl 
 
 investment material on tlie pattern. The same could obtain in placing the compound for an artificial 
 stone model in the impression. Undue pressure will force, or distort, a mold as a whole. Not as 
 l>eads. Beads will not form unless the spaces for them are already there. 
 
 Dr. Lodge quotes Dr. Price on pressures, contraction, etc. While we must admit that Dr Price 
 has worked out a beautiful technique on theory, yet we have not been able to obtain from his writings 
 — and we believe we have read most, or all, of them — certain data, or technique, that must of necessity 
 belong in order that his technique may obtain as he claims for it. This data is — the lemperalure thai 
 the mold must have at the moment of casting, and a means of determining that temperature. Dr. Price has 
 ingeniously devised an artificial stone that has a permanent expansion equal to the normal expansion 
 of gold up to its fusing point. Granting this equalization, then any rise in temperature in the flask at 
 the moment of casting means an increase in the size of the casting over and above zero measurement. 
 In order to roughly demonstrate to you the effect of variation of temperature in the flask at the moment 
 of casting, we have here a small mandrel on which are two gold rings. The mandrel has a taper of 
 1 degree; the patterns for the rings shown here were made at exactly the same point on the mandrel; 
 both were invested in the investment material that we have advocated, and from the same mix, or bowl 
 of batter. There could, therefore, be no possible difference in physical conditions thus far. One ring 
 was cast in a mold as hot as the fusing point of the brass flask which contained it would allow, and the 
 other cast in a flask that was cool enough to handle with the fingers at the moment of casting. You will 
 notice that one ring drops to within the tiniest line of the point where the patterns were made, and the 
 other ring stops about 3-8 of an inch further up. Therefore, in order to make a given technique com- 
 plete, data for the temperature of the flask at the moment of casting should be given. 
 
 The figures given us by Dr Lodge — giving the eft'ect of pressure as determined by Dr Price — are 
 in error. Dr. Price obtained these figures by experimenting in casting with a centrifugal machine. 
 In the same article in the Items of Interest, wherein Dr. Price gives us these figures, he states that in 
 computing pressure in such a machine, the entire mass of gold in the crucible is available, and must 
 be reckoned in computing the pressure on the sprue area. This is unquestionably an error. An 
 inflexible law of physics teaches us that the only bulk of gold available for pressure and computation, 
 under such conditions, is a bulk equal to the area of the narrowest part of the sprue opening, and the 
 length of which is the height of gold in the crucible. All the remaining bulk of gold that fills the rest of 
 the funnel-shaped crucible adds absolutely nothing to the pressure on the actual sprue area. Therefore, 
 all the figures that are based on this theory and method of computation, are certainly in error. We 
 recall having seen cuts of a device that was to produce perpetual motion, and will sketch the same on 
 the blackboard. The device is a funnel-shaped receptacle, having a long curved neck or spout, that 
 curves aside, upward past the body part, and again curving so as to have its final opening directly 
 over and pointing toward the open top of the larger or funnel part. The belief was, that water placed 
 in the large part of the device would exert so much force through the small curved spout that a con- 
 tinuous flow would be established around and into the original receptacle. Of course, it did not 
 work, and for the reason we have mentioned. 
 
 As we stated a few moments ago, unless all these experiments are worked out on a truly scientific 
 basis, and in strict harmony with the known inflexible laws of physics, such research can avail little or 
 nothing, as a means to an end. 
 
102 PRACTICAL MANUAL OF DENTAL CASTING 
 
 CAST PINS FOR CROWNS 
 
 By W. A. Stewart, D.D.S., Kansas City, Mo. 
 
 This pin is to be used when and where a pin is needed in a tooth; for example, 
 a Richmond crown, to help anchor inlays, in broken down teeth, or to be used in 
 root or roots of molars that are to be built up. 
 
 ADVANTAGES 
 
 1. It is tailor-made and fits. 
 
 2. No part of the tooth is taken away that is not filled by the pin. 
 
 3. It tapers, making it the shape of the root, and does not weaken the tooth at 
 farther end of pin, leaving it plenty large enough at the other end. 
 
 4. Never fits until it is in place, leaving plenty of room for cement to be dis- 
 placed. 
 
 5. The pin is made before the patient comes, and will fit as soon as it is placed 
 in the canal. 
 
 6. Always stays in place while working around it before it is cemented. 
 
 7. Impression is not taken in wax. 
 
 DIRECTIONS TO MAKE 
 
 Fill the ring with investment and let it dry; drill a hole with reamer in invest- 
 ment, then cast; drill a hole in the tooth with the same reamer, any depth desired; 
 try pin in and see that it fits; if it is too long cut it off. I use 22k. gold. 
 
 A METHOD FOR CASTING BACKINGS FOR ALL-PORCELAIN FRONTS 
 FOR CROWNS AND BRIDGES 
 
 By D. Haight, Coshocton, Ohio. 
 
 Take any of your old cast-off facings or broken plate teeth that have no pins, of 
 any shade that will suit the case, or a Steele facing, and grind flat like a Steele facing. 
 Grind it on the cutting edge as sharp and thin as you can. Grind ofT the cutting 
 edge to be supplied the same length you would grind the porcelain for a gold tip. 
 Take a knife-shaped carborundum stone and cut a groove lengthwise about the 
 depth of a Steele facing, having the walls parallel. Take inlay wax, shape it as you 
 want your backing, and have a good tip on cutting edge, for these are the secrets 
 of success; then remove and cast. After it is cast cut serrations in the gold lug with 
 a knife-edge carborundum and cut little undercuts in groove. See that your facing 
 fits perfectly to the backing. When you use for bridge or crown work, just before 
 you invest, be sure and use antiflux so that no solder will run where your facing 
 goes. I find Harvard cement the best for cementing the porcelain to the backing. 
 I have had perfect success with this work for over fifteen years. By burnishing 
 platinum on facing, the same as porcelain filling process, but since the process of 
 casting, it is much more simple. In case of breaking one out another can be ground 
 in without taking off the bridge. 
 
RESTORATION OF BADLY BROKEN-DOWN ROOTS WITH ACOLITE 
 
 By James B. Lester, D.D.S., Christianburg, Virginia. 
 
 The saving of badly decayed roots is a thing too often neglected by the dentist. 
 I have reference to those roots where decay has progressed far be^'ond the cer\ucal 
 portion. 
 
 In my judgment the condition of these teeth arises from one of two principal 
 causes; first, many persons fail to realize the importance of caring for the teeth until 
 they are badly broken down, and then they present themselves for extraction because 
 of alveolar abscess; second, many people are too miserly to have their teeth cared for 
 until they have lost a large number, and they realize their inability' to properh' 
 masticate their food. 
 
 The first class can generally be convinced of the importance of caring for their 
 teeth. The second are easily convinced that their teeth are important to them. 
 
 In mouths of this class of patients we often find rocts that are covered with gum 
 tissue. After the decay is removed the end cf the root is beyond the cervical line, 
 hence, in my opinion, it cannot be restored with any material that is placed there in a 
 plastic condition, because it would be impossible to make a restoration smooth and 
 of proper contour be^'ond the gum line. 
 
 Because the restoration of these roots to their normal usefulness is tedious, 
 many dentists condemn them to the forceps and replace with bridges. 
 
 In my practice, if there is two-thirds or three-fourths of a root left after the 
 decay is removed, and that portion solid, it is worth an effort to save. 
 
 When these cases present themselves for consideration my first step is to remove 
 all decay as nearly as possible. This will generally cause hemorrhage from the 
 wounded gum, which is stopped with adrenalin. The end of the root is thoroughly 
 dried, and the canal or canals treated with formocrescl. A piece of temporary stopping 
 of sufficient size to fill the cavity (in gum) is thoroughl}' softened and made into a 
 cone, or other appropriate shape, and forced in place so as to move the gum tissue 
 out. The patient is dismissed to return a day or two later, and at the next sitting 
 all decay is thoroughly removed, the canal cleansed and again treated with formo- 
 cresol, and the cavity packed as before. The patient is dismissed for five or six days 
 and on returning the canals are sealed at the apex, if they are in proper condition; 
 if not, this is done at a later sitting. The end of the root will generally be well 
 defined, and you are now ready to begin the restoration. 
 
 If the root is an anterior one an all-porcelain crown with attached jiin is selected 
 that is long enough to allow the porcelain to extend beyond the gum margin, thus 
 avoiding the possibility of a dark joint at the gum line. The pin is ground to proper 
 length, and inlay wax that has sufficient rigidity to stand carving is chosen. (I 
 personally prefer the Standard, put up by The Ransom &; Randolph Co.) A sufficient 
 quantity of this is softened and placed around the base of the pin, so as to leave an 
 excess. While the wax is fairly soft the crown is pressed into place and held firmh- 
 until the wax is hard. Crown and wax are now removed, the wax is trimmed to the 
 size of the root and crown, the piece is again put in place to ascertain if the adaptation 
 is perfect. A sprue wire is attached and the case is invested as directed for casting 
 
104 PRACTICAL MANUAL OF DENTAL CASTING 
 
 acolite. That process I will not describe here as it would be taking unnecessary 
 time. After casting, the metal is polished and the work tried in to ascertain if the 
 adaption is now perfect. If it is, the piece is set with cement, care being used to have 
 as little excess cement as possible, as it is more or less difficult to remove excess 
 from under the gum and any left would act as an irritant. 
 
 If the root is a molar, and you wish to use a gold shell crown as an abutment 
 for a bridge, pins are arranged parallel to each other in the enlarged canals. A 
 large piece of wax is softened and pressed up on pins, and allowed to harden. Wax 
 and pins are now removed, the wax is trimmed to the size of the root as shown by 
 the impress. If the wax does not extend sufficiently above the cervical line, more 
 wax is softened and shaped on the end of the piece already in hand. The piece is 
 now invested and cast. By this method we have supplied a stump to which a gold 
 shell crown is easily adjusted. 
 
 I have suggested the use of acolite in the restoration of these roots because it 
 can be done at a much smaller cost to the patient than would be possible if gold was 
 used, and at the same time done well. 
 
 Where molars are too badly decayed to fill with amalgam and on account of 
 cost the patient cannot have gold inlays, this same method may be used to make 
 acolite inlays that will give comfortable service. 
 
 CAST ANTERIOR BRIDGE ABUTMENTS AND VARIATIONS OF THE 
 SAME FOR PERMANENT SPLINTING OF LOOSE TEETH 
 
 By George C. McCann, D.D.S., Danville, 111. 
 
 Doctor McCann's table clinic demonstrated the technique and use of two 
 anterior bridge abutments — one consisting of a root canal dowel, with lingual and 
 proximal gold backing attached. The enamel of the tooth (preferably six anterior) 
 being ground so as to accommodate the occlusion with sufficient thickness of gold. 
 The margins of the backing carried to self-cleansing areas. The other consisted of 
 an anterior attachment for a live tooth (preferably bicuspids). Trimming the lingual, 
 occlusal and proximal surfaces to accommodate thickness of gold and to self-cleansing 
 areas. A groove is then produced with a millimeter cross cut fissure bur over the 
 proximal and occlusal surfaces. 
 
 Splints for loose anterior teeth were modifications of the abutments. For the 
 lower anterior, axial directed pits, 1.5 to 2 m. m. in depth were made on the lingual. 
 Into the pits stub pins were placed and a casting made supporting pins and furnish- 
 ing a solid lingual backing to the teeth; a splint was then soldered to either form of 
 bridge abutments placed on sound teeth. 
 
 A posterior splint consisted of a wire placed in an occlusal groove of loose teeth 
 and supported by inlays located in sound abutting teeth at each end. 
 
 The purpose of the clinic was to present strong esthetic abutment of anterior 
 work by confining the case to the lingual aspect. 
 
ANCHOR FOR FILLINGS AND INLAYS 
 
 By W. H. Pelton, D.D.S., Fostoria, Ohio. 
 
 Every dentist has experienced the difficulty of anchoring large fillings and 
 inlays, particularly in approximal cavities, where the gingival and incisal portions 
 are involved in the cavity. The failure of such fillings is due to the fact that we 
 depend upon frail enamel and cement to anchor the filling or inlay. Naturally, 
 these elements have a lesser resistance than the filling or inlay. 
 
 The anchoring device I here present is so fashioned that it forms an inter- 
 locking union of metal with the tooth and filling that has as great a resistance as the 
 tooth or filling. With the anchor you depend on a 22 gauge 18k. gold post set in 
 the sound dentine to anchor the filling or inlay at the' incisal edge and at the gingival 
 portion one end of the anchor is set in the sound dentine. The anchor post is bent 
 at a right angle and interlocks with the anchor, forming a po.sitive lock of gold with 
 the tooth and filling or inlay. 
 
 We will consider first the preparation of a cavity in a central for a gold filling, 
 it being unnecessary to devitalize. After removing decay, take sandpaper disc and 
 cut the labial and lingual enamel parallel with the long axis of the tooth, then with a 
 carborundum stone cut a flat gingival seat. Bevel the labial and lingual enamel 
 
 Fig. 1 
 
 Fig. 2 
 
 according to your own idea and build up the pulpal floor with cement until it is flush 
 with the labial and lingual enamel, leaving no undercuts or concave surfaces. Drill 
 a hole (Fig. 1) in the gingival seat to receive one end of the anchor and drill a hole in 
 the pulpal wall near the incisal edge at an acute angle with the pulpal wall. Place 
 one end of the anchor in the gingival pit and pass the anchor post through the hole 
 in the anchor and into the hole in the pulpal wall previously filled with cement. 
 The anchor is so formed that flanges are bent at a right angle and extend labially 
 and lingually. The gold is condensed between the pulpal wall and the flanges, 
 and as the filling is built up each portion of gold is interlocked with the anchor. 
 Non-cohesive gold can be used in the first two-thirds and cohesive in the remaining. 
 This anchor is indicated in bicuspids and molars where large cavities are restored 
 with amalgam. It is unnecessary to involve the enamel in the retention of the filling 
 — the anchor will resist the stress and retain the filling. 
 
 The casting machine creal;ed the greatest enthusiasm among the dentists, yet 
 many a man has to regret that the cast inlay has been cxpensi\c to his practice, 
 
106 PRACTICAL MANUAL OF DENTAL CASTING 
 
 yet the failure of gold inlay in large restoration is due to the cement not being strong 
 enough to resist the stress. The anchor enables us to go one step forward, which 
 gives us an inlay with a mechanical retaining device. The cavity for inlays is pre- 
 pared similar to the cavity in Fig. 1. 
 
 We will now consider an inlay in a central (Fig. 2). 
 
 Cement the pulpal floor flush with the labial and lingual walls, leaving no under- 
 cuts; drill a hole in the gingival seat with a round bur, to receive one end of the anchor; 
 then drill a hole near the incisal edge for the post; now cement the post to place 
 with the right angle part parallel with the long axis of the tooth and pointing toward 
 the incisal edge. Continuing, place the tube part (Fig. 2) of the anchor in position 
 in the cavity — seeing that the full round part of the tube interlocks with the post, 
 then adapt the inlay wax and carve the wax to conform with the tooth. Now remove 
 the wax model by pulling it straight away from the cavity (there being no undercuts 
 the wax will come away without being distorted). The tube part of the anchor 
 will come away with the wax. Invest the wax model with the tube part of anchor 
 in place just as it is taken from the cavity. The tube must be filled with the invest- 
 ment (using a camel's hair brush). When you cast, the gold will fuse to the anchor, 
 making the anchor and inlay in one piece. 
 
 Fig. 3 
 
 In using the inlay anchor in the construction of bridge work (Fig. 3) the cavity 
 is prepared similar to inlay in Fig. 2. The anchors are placed in position and the 
 cavities built up with the inlay wax; a suitable facing is then attached to the wax 
 in the cavities, then the wax model is removed and invested as in Fig. 2 and cast. 
 This will give you a beautiful piece of work that is sanitary and is constructed with 
 less sacrifice of tooth substance than by any other known method. 
 
 CAST POSTS FOR STEELE'S FACING 
 
 By George H. Walker, Los Angeles, Cal. 
 
 This is a portion of a gold rib cast. One end is cut and shaped for the anterior 
 teeth and the other for posterior. Wax is forced about the rib when in tooth and 
 shaped to suit. Facing then removed and the wax invested and a casting made as 
 per finished tooth. 
 
 A sheet of base-plate wax is placed on a flat surface at the edge, and, beginning 
 with the largest hole, the draw plate is drawn over the edge of wax, gradually cutting 
 wax down to size of smallest hole. Wax is then cut from sheet, forming strips, 
 as per sample — a sprue attached to one end — coiled like watch spring, flasked and 
 cast. Wax must be chilled to draw nicely. 
 
METHODS OF CASTING IN CROWN AND BRIDGE WORK 
 
 Dy W. G. Crandall. D.D.S., Spencer, Iowa. 
 
 ALL CAST CROWN 
 
 It is posLible to cast an entire gold crown, and it is at times practical. It makes 
 a piece of work that is heavy, expensive and difficult to handle. 
 
 It is always necessary to have a tooth perfectly trimmed of all enamel before 
 starting to make a crown. It is absolutely essential that there be no overhanging 
 wall of dentine. 
 
 If the tooth has one or more walls of dentine, build it up with amalgam so that 
 the walls slightly converge toward the occlusal. Next give the surface a finish with 
 strips or discs. The casting wax may be applied directly over the prepared tooth if 
 the operator is skillful enough to carve and finish while in position. This is not an 
 easy thing to do unless the gum has previously been forced out of the way to give 
 access for convenient finishing about the root. 
 
 The easier way is to take an impression with gutta percha, metalline, modelling 
 compound or cement. With a burnisher work the impression material close about 
 the root, being sure that the impression is perfect. Do not allow the impression to 
 interfere with occlusion. When the impression material is thoroughly hardened take 
 the bite with modelling compound or wax, bringing away the root impression in 
 position in the bite material. 
 
 Fig. la Fig. lb 
 
 The roct impression should be coated with some separating material and then 
 filled up with cement; either build down quite long or rough so that it will be held 
 firmly in the plaster model or insert metal pins for that purpose. 
 
 The case is now ready to place in crown articulator and pour up with plaster. 
 
 When hard, remove the bite and impression and you have an exact reproduction 
 of the tooth, approximating teeth, occlusion and surrounding parts. 
 
 Either wet or oil the model, then proceed to melt on the casting wax a few drops 
 at a time and carve to form. It is possible to give form to a crown in this manner 
 that it would be very difficult or impossible to form with contouring pliers. A fit 
 beneath the gum line may be made as perfect as that of any inlay and this is more than 
 can be said for most gold crowns. 
 
 A most perfect fit at the gingival line may be made by cutting a seat at right 
 angles to the long axis cf the root upon the mesial and distal surfaces just beneath 
 the free margin of the gum (Fig. 1) and finishing the crown flush with this line. 
 
 The possibilities of the contacts and contours are limited only by the variety 
 of cases and the skill of the operator. 
 
108 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 CAST CUSPS 
 
 In making cast cusps for a crown the band should be made in the usual manner, 
 paying very little attention to contour. Take bite or impression in the usual 
 manner and place on the articulator. A thin film of wax within the band at the 
 gingival portion will facilitate its removal when upon the model. 
 
 The root model may be built down with plaster so as not to leave room for too 
 great a thickness of casting wax and a subsequent thickness of gold. The wax can 
 be melted over the surfaces of the band, giving buccal, lingual and approximal 
 contour with precision. The occlusion can be tried and carved to an exactness. 
 
 The waxed up model of either variety of crown should be thoroughly trimmed 
 and smoothed (gasoline or chloroform is good for this purpose) so that none of the 
 contour need be filed or polished away. 
 
 Fig. 2 
 
 The sprue wire should be inserted into the wax of the occlusal portion within 
 the crown (Fig. 2). This is important when casting upon bands, as will be seen later. 
 
 In investing these crowns they should be placed as near the surface of the in- 
 vestment as the strength of the investment will allow. It must be remembered 
 that the occlusal surface of most crowns is quite a large surface and there must be 
 sufficient investment material to warrant a resistance to the molten gold when it is 
 thrown against it. It has been my experience that a depth of from 3 to 5 m. m. 
 should be allowed for sufficient strength. 
 
 After the investment material has become sufficiently hard (15 to 30 minutes 
 will suffice for most investments) the sprue wire should be removed and the case 
 inverted over a flame that will melt and burn out the casting wax. When the in- 
 vestment becomes red with the heat it should be inverted and heated until the 
 investment can be seen to be at a white heat through the sprue hole. This is im- 
 portant, for the gold will not fuse to the band unless it is well heated. A failure will 
 be unknown if the case is thoroughly heated and properly cast. 
 
 If a taper pointed sprue has been used, the crown when cast can be easily 
 separated from the cast sprue by twisting in the fingers. A separation can be had 
 at just the right point if care has been used in placing the sprue in the wax and an 
 excess of wax not allov/ed to adhere to the sprue. Anj- excess remaining can easily 
 be cut out with a bur or small stone. 
 
 A crown made after this method will need very little polishing to produce a 
 beautiful result, providing care Was been taken in every step. 
 
 The Richmond Crown is practical upon any of the teeth that will admit of a 
 sufficient length for the porcelain facing. 
 
METIIODS OF CASTING IN CROWN AND liRIDCE WORK 
 
 101) 
 
 liKIDCiK WdKK 
 
 \Vl' will suppise thai thi; l^oKI cruwii we ha\x' just cast is for the upper left first 
 molar, the two bicuspids are missing, the bite is very clcse and we want to place a 
 Richmond crown upon the left cuspid and bridge the space. 
 
 Before making our Richmond crown we will trim the root a little differently 
 than the usual custom. The labial half of the root end is beveled beneath the gum 
 line with a root facier and stone as for a Lcgan crown. The lingual half of the root 
 end will not be beveled nor cut down to the gum line, but will be cut flat, making a 
 good seat for the crown. The enamel should now be thoroughly remo\ed from the 
 root (Fig. 3). 
 
 An iridio-platinum wire ai)out 16 gauge is fitted to the canal and left protruding 
 from the root end about 2 m. m. A suitable facing is ground to position, allowing 
 room for a gold tip for the protection of the facing. The pins should be bent so as 
 not to interfere with occlusion or the contour of the crown. 
 
 A piece of casting wax of sufficient si.'.e should now be scftened, or better, melted 
 upon the back cf the facing, approximating the shape of a crown, and the root pin 
 inserted. This, while soft, should be forced upon the root, the facing adjusted to 
 
 the desired position and occlusion carefully noted. The wax should be tightly 
 burnished about the root with cold burnisher. After thorough adjustment, chill 
 anil remove for careful trimming. Casting wax that is sufificicnth' hard to admit of 
 handling and trying in che mouth without danger of changing form, should be used. 
 When the desired form is secured and the wax smoothed the sprue wire should be 
 inserted in the wax upon the lingual surface of the crow-n at right angles to the back 
 of the facing. 
 
 Great care should be taken that no wax extends over the labial, mesial or distal 
 surfaces of the facing as this would be liable to cause a check in casting. 
 
 This arrangement places the facing in the position to receive the most possible 
 heat in the investment. The investment should be made the same as for the gold 
 crown, the wax melted out, the case inverted and heated slow !>• at first. gradualK' 
 
no PRACTICAL MANUAL OF DENTAL CASTING 
 
 increasing the heat to the extreme, so that when the hot gold is cast upon the facing 
 there will not be enough difference in temperature to cause sufficient expansion to 
 check the facing. 
 
 The moment the cast is made and the gold has hardened the case should be 
 covered with dry plaster and left until thoroughly cool. Most of the failures in 
 casting onto facings have been due to rapid cooling. Powdered plaster will keep 
 the case warm for about a half hour or more and it is time saved to leave it plenty 
 long enough. 
 
 A crown made carefully after this method should go to place on the root as per- 
 fectly as any inlay and if properly finished should never become an irritant to the 
 gum tissue. 
 
 To complete our bridge we will place the crowns in position and take accurate 
 bite and impression. This is easily done with plaster on the Detroit bite impression 
 tray, bringing the crowns away in position and allowing no chance for change of bite. 
 
 The inside of the crowns should be coated with a thin film of wax and the case 
 mounted in plaster on the articulator. Separate and warm crowns sufficiently to 
 melt wax and thoroughly clean out all wax so that crowns rest perfectly in position. 
 
 Bicuspid facings are now ground and fitted, casting wax applied to them, and 
 while warm they are placed in position and the articulator closed and worked about 
 as in chewing. Now carve cusps and trim wax as you want the bridge when finished. 
 Use great care that wax does not overlap the facings in any position. It should cover 
 the same portion of the facing as you would include in backing a tooth for soldering. 
 The case should be invested and cast the same as the cuspid crown. It is now ready 
 for assembling. This is not done in any way different from the ordinary procedure, 
 with the exception that very little solder is necessary. 
 
 This makes a bridge that is nearly perfect hygienically. There is no space 
 between the facing and gold as with ordinary backing, there are no solder pits to 
 cause trouble in finishing. The crowns fit like inlays, allowing a minimum of cement 
 which we all know is the foulest of substances when removed from an old crown. 
 
 The color of the gold should be uniform, the same kind of gold being used 
 throughout. 
 
 In casting anterior cases where it is desirable to have the case thin linguo- 
 labially, I would suggest clasp metal. Though difficult to melt sufficiently to cast, 
 it gives the maximum of strength and rigidity for its bulk. 
 
 If it is desirable to have the facings removable, the backs of the facings should 
 be oiled and the pins left straight. After the waxing up has been completed, remove 
 facings and place sharpened pencil points in the pin holes, having the points long 
 enough for the investment to hold in position for casting. Facings can be easily ad- 
 justed and cemented to position after bridge is completed. 
 
 Another good method for making facings removable and a strong attachment 
 when in position, is done by bending the pins down on the facing so they lap, and as 
 close together as possible. Then cover with soft solder or some of the easily fusible 
 metals. Grind this into a box form just so that it can be withdrawn from wax 
 without pulling. This makes a very strong attachment and is easily and quickly 
 made. 
 
AN IDEAL BICUSPID OR MOLAR CROWN 
 
 By George S. Schlegel, D.D.S., Reading, Pa. 
 
 An ideal artificial crown is one that possesses all the qualifications of its natural 
 predecessor. In fact, the artificial substitute cannot decay, can be easily repaired 
 if broken, and very often makes a better appearance than the natural tooth, when 
 the latter is affected with atrophy of the enamel, discolorations, and partial fractures. 
 In order that I be not misunderstood, I wish to inform my readers that a tooth should 
 not be crowned unless it cannot possibly be repaired with some permanent filling 
 material suited to the class and position of cavity or cavities. 
 
 The crown I wish to describe is made possible by the application of the principle 
 of casting gold under pressure. The method can be used for any tooth in the mouth, 
 but is especially adapted for bicuspids and molars. No ethical dentist should place 
 a gold crown on the oral teeth, but bicuspids and molars are crowned by them, 
 with the hollow shell crown, because the repertoire of crowns used to date lacked 
 one that possessed both the necessary strength and esthetic qualities. I will point 
 out the value of this crown to others now commonly used by comparison at the con- 
 clusion of this article. 
 
 In order to give you a clear conception of this method, I will describe how to 
 make a superior first bicuspid crown: 
 
 The proper preparation of the root is essential for the proper adaptation of 
 the crown as for any other crown. The root should be filled with red gutta percha 
 points, which serve as a guide in reaming the root canals, the little red spot indicating 
 the direction of the root. The diameter of the canals should be enlarged in propor- 
 tion to the diameter of the root. I use No. 16 to 20 gauge iridio-platinum wire in 
 the roots. 
 
 The next step is to cut down the root flush with the gum line. Then bevel root 
 on the buccal side, and palatal side to about one m. m. below the free margin of the 
 gum. Take a No. 5 or 6 bur to countersink opening to the reamed root canal to 
 the depth of IJ^ m. m. I insert iridio-platinum wire into each canal, cut flush with 
 surface of root, and remove to bracket table for future use. This completes the root 
 pre]:)a ration. 
 
 The next step is the selection of a porcelain detachable crown of any make 
 desired, but of such a size and color that will conform to the case. If necessary 
 to grind to occlusion, grind the occlusal surface; the reasons for this I will point out 
 later. 
 
 Now take a piece of black inlay wax of a rather stiff quality, like S. S. White's, 
 and after lubricating the inside of the opening of the artificial crown with a little 
 sweet oil or glycerin, press the wax, which was previously warmed, into the opening 
 of the tooth. Withdraw^ to see if the undercuts in the tooth interfere with proper 
 removal, and if they do, correct the fault. Return wax to crown, and trim approxi- 
 mately. Warm slightly and press crown with wax to the root. Note the condition 
 of occlusion, position in arch, etc., then chill with iced water and remove. Note 
 the opening to the canals by the elevation in the wax. Heat the iridio-platinum 
 pins previously fitted in the roots, and place in approximal position in wax. Return 
 
112 PRACTICAL MANUAL OF DENTAL CASTING 
 
 to root for final adjustment. Be sure that all the wax is hidden beneath the gum. 
 Chill again, remove carefully from root, then remove wax from the crown. Care- 
 fully insert a sprue wire at the end of the wax with pins, which touches the remotest 
 part of the opening in the artificial crown. Invest and cast according to any of the 
 methods used in casting gold inlays. Cement crown on cast base, and then cement 
 the crown and base to place. 
 
 This gives you a crown that is perfectly adapted, esthetic, durable and easy to 
 repair. The reason for grinding the occlusal surface is obvious from the fact that 
 repairs would be easier if a record is kept of the number of the mold used, then a 
 tooth of the same mold will fit the case without any grinding at the gum line. 
 
 It is my firm conviction, gained from actual experience with the insertion of 
 these crowns for a period of over a year, that they are ideal. They are better than 
 a gold crown for esthetic reasons. Better than a Richmond crown because in this 
 ideal crown no band is needed, for bands are an abomination at best, and unless a 
 Steele's Detachable Facing is used, the color is often far from satisfactory. Again, 
 gold tips are unsightly. Better than a Logan crown because it is very often difficult 
 to adapt to the root. Again, the leverage on the pins is very great, and often ends 
 in the splitting of the roots. Better than a porcelain or platinum jacket crown, 
 because either is liable to fracture, and difficult to repair. 
 
 CAST ABUTMENTS FOR THE ATTACHMENT OF BRIDGES 
 
 By W. M. McCall, D.D.S., Louisville, Ky. 
 
 Cast abutments for the attachment of bridges, using in this case, superior left 
 cuspid to first molar. 
 
 Prepare the cuspid, first by removing with the stone sufficient amount of tooth 
 structure from lingual portion of tooth to give room for construction of inlay. Grind 
 two small grooves across lingual surface, then with small round bur make three 
 openings, two towards incisal, one towards gingival. In grooves which were made 
 in tooth, fit number twenty (20) platinum wire and proceed to construct the inlay in 
 the usual manner. 
 
 To prepare the molar tooth, grind off occlusal surface, starting at lingual and 
 gradually tapering towards buccal surface. Then cut cavity in mesial portions, 
 extending under free margin of gum, and from lingual to buccal of mesial surface, 
 placing in the occlusal two or three number twenty (20) platinum pins, so as not to 
 come in contact with the pulp of the tooth. Proceed to construct inlay in the usual 
 manner. Place inlays in position, take bite and impression, using for dummies 
 Brewster's diatoric teeth. Grind up dummies, swage backing and solder as in ordi- 
 nary piece of bridge work. A bridge properly constructed and attached by this 
 method is very ?trong and durable. The main feature is that no gold shows on labial 
 and buccal surface. 
 
THE SCOPE OF CASTING IN DENTISTRY 
 
 By R. C. Brophy, M.D., D.D.S., Chicago, III. 
 
 While casting metals in dentistry is by no means of strictly modern origin, it 
 is only of late, or following the announcement of the application of the principle 
 to operative work by Dr. Wm. H. Taggart, that it has come to be regarded with 
 particular interest by the profession. It is doubtful, however, if, with all the interest 
 shown at the present time, the complete scope of the work, or full field in which it is 
 applicable, is properly appreciated. 
 
 It is not the purpose of the writer to dwell upon the casting of inlays proper, as 
 substitutes for fillings, for that subject is being widely discussed, and is quite well 
 understood, but I would, taking that as a starting point in consideration of my 
 subject, follow along further and take up other things in the same field. 
 
 I have always felt that there are possibilities in the process of casting in den- 
 tistry of really greater value and importance than the casting of inlays to fill cavities 
 in the crowns of teeth. 
 
 Making use of inlays is dependent upon the extent to which destruction of the 
 crown of a tooth has been allowed to proceed; their applicability must be measured 
 by the proportion of the crown remaining; there must be a given area of sound, 
 solid tooth structure to support them. Many cases present where there is not such 
 sufficient sound structure, and it is in such instances, in the writer's opinion, that 
 there lies the greater possibilities of valuable accomplishments through the casting 
 process. 
 
 It is a pity that teeth are allowed to pass beyond the pale of repair by simply 
 plugging cavities; but the time will never come when the dentist will not meet con- 
 ditions either presaging the complete loss of the tooth, or, exacting extreme ingenuity 
 and skill in its saving. It is not so much a question as to whether the dental pro- 
 fession could keep everybody's teeth in normal condition, and intact, as it is a fact 
 that it never will have an opportunity to do anything of the kind. People sometimes 
 neglect to lock the barn door until after the horse is stolen. A great many people 
 never entertain a thought of consulting the dentist until their teeth are so extensively 
 involved in destruction that artificial restitution is demanded. 
 
 Then, again, the matter of casting inlays proper applies only to those cases 
 where restoration of a tooth may be accomplished by old, ordinary methods of 
 operative procedure. I want to connect the casting process with those cases which 
 no dentist would think for a moment of attempting to restore by operative procedure, 
 those cases in which the little remaining structure, merely the shell of a root, though 
 it be, are made use of as an abutment or anchorage for a cast restoration, or the 
 mounting thereon of a porcelain crown. 
 
 It is scarcely possible to conceive of a tooth assuming a condition of deca> , 
 which, from a mechanical standpoint cannot be restored, if the casting process be 
 employed, waiving, however, discussion of the many things that may be done in the 
 way of restoration of the crown of a tooth where the root is sound and solid. I 
 would speak particularly of that procedure which I believe constitutes the most 
 
114 PRACTICAL MANUAL OF DENTAL CASTING 
 
 valuable and important achievement possible in casting. I refer to the mounting 
 of crowns upon badly decayed roots where, possibly, but a shell remains, and this 
 shell buried beneath the margin of the gum. 
 
 The method of making such a restoration is so simple that it can but appeal to 
 all. If the shell upon which it is desired to mount a crown be deep down underneath 
 the gum, it will be found that gum tissue has covered, and likely, partially filled it, 
 and in that case this tissue must be crowded back by packing. The root should then 
 be cleaned of all debris and its edge trimmed to a solid margin. 
 
 If the restoration is to be made of gold, a detachable pin crown should be used, 
 the dowel, or pin, with the crown in position upon it, should be invested with softened 
 inlay wax and should be crowded down into the root, the latter having first been 
 moistened with saliva. This procedure should give a perfect model of the canal, 
 or shell, and a perfect mold of the base of the porcelain crown. The crown may 
 now be taken off the dowel, and the latter, with the wax model attached to it, may 
 be lifted out, trimmed, reset, removed again and retrimmed, until finally the wax is 
 found to be perfectly adapted. The crown should then be removed, the sprue wire 
 attached, and the case is ready for investing and casting. 
 
 If, instead of making the restoration with gold, Acolite be used — and for these 
 cases the writer does not hesitate to say that he regards Acolite preferable to gold — 
 the cast may be made direct to the porcelain, or not, as is desired, and ordinary 
 vulcanite plate teeth and German silver dowels may be used instead of special 
 crowns with their dowels. After the restoration is finished it may be set with 
 cement, and if the crown used be detachable, it may then be cemented in position 
 on the dowel. 
 
 The casting process in relation to bridge work is an important consideration, 
 but one upon which I realize that I have peculiar views. I believe that if porcelain 
 teeth of a detachable or removable character could be made use of, and as a matter 
 of fact they might be, that casting bridges would be practical, but I am led to 
 believe that unless the bridge be cast along that line that it better not be cast at all. 
 
 I have long felt that casting gold to porcelain is too uncertain and questionable 
 to be practical or advisable. It is true, of course, that a piece of porcelain will now 
 and then be found to have withstood the shock and the effe-ts of the natural changes 
 of the gold, after the two have come in contact, but I know that such occurrences are 
 very rare. In a very great many instances the porcelain plainly shows checks. 
 In very many instances the porcelain appears to the naked eye to be uninjured, but 
 my experience has shown that in almost all cases examination under a magnifying 
 glass will reveal checks. These checks, of course, weaken the porcelain and make 
 it unreliable and unworthy of dependence. I regard the casting of gold to porcelain 
 as impracticable. 
 
 What I have said in relation to casting Acolite in crown work applies to bridge 
 work. Acolite, owing to its low fusing point and its non-changing qualities in con- 
 gealing, may be cast to porcelain without danger of checking it. 
 
 Casting metal plates in dentistry has been done in our own country for fifty 
 years, and a study of the subject from a standpoint of evolution is interesting. Dr. 
 James B. Bean, who was the first dentist to experiment in the work, undoubtedly 
 was actuated in so doing by a desire to make use of the then practically new metal 
 — aluminum — for base plates. It is doubtful if the metal was procurable at that 
 time in sheet form for swaging. Dr. Bean attempted to make use of straight aluminum 
 without trying to affect any change in it by alloying. When we realize that pure 
 
THE SCOPE OF CASTING IN DENTISTRY ll5 
 
 aluminum is not produced at the present time, we may imagine the purity tf the 
 metal he used at that early time, and, knowing what we do cf the effects produced 
 by certain oral secretions upon the "pure" aluminum with which we are now 
 supplied, we may further imagine the troubles which confronted him in practice. 
 It is quite likely, also, that Dr. Bean had his troubles in making perfect casts, for 
 he depended upon gravity to inject the metal into the matrix, or mold. 
 
 Following Dr. Bean, other men became interested in casting aluminum plates, 
 notably Dr. Carroll and Dr. Zeller, but without commenting upon their experiences 
 I will consider the matter from a present day status, and purely from a mechanical 
 standpoint, in conformity to the title cf my paper. 
 
 It may be interesting to some to know that as long as fifteen years ago the 
 writer, as well as other dentists, made use of the identical principle in casting plates 
 that is being employed by many at the present time, in the so-called inlay casting, 
 viz., burying the model, using a crucible former and sprues, burning out the wax 
 and forcing the metal down into the matrix with air pressure. 
 
 The casting of plates is an extremely important phase of dental casting, and is 
 found at the present time to be following very closely the wonderful development 
 and gain in popularity of other forms cf dental casting. While I do net deem it 
 advisable to make a practice cf casting large full base plates in gold, there are cases 
 where delicate horseshoe or saddle plates may be cast in this metal to advantage. 
 
 In the casting cf Aerdentalloy plates, a well known alloy of aluminum, which 
 has been proven to possess characteristics making it vastly superior to straight 
 aluminum for the purpose, the dental profession has one cf the most, if not the most, 
 important of all the many advantageous aids resultant from the process cf casting. 
 
 Casting in dentistry has a practically unrestricted scope, and its value to the 
 profession and to humanity cannct be computed. 
 
 A SIMPLE METHOD OF CASTING PIN AND COPING FOR 
 A PORCELAIN CROWN 
 
 By Paul J. Boyens, Weed, California. 
 
 Select a detached post crown to fit the case and fit it to the root in the usual 
 manner. Ream the canal with a gradual taper, making the orifice a trifle larger 
 than for the ordinary post. This increase in the size of the cast post at the point 
 of greatest strain will more than compensate for the difference in strength between 
 the cast material and a platinum or iridio-platinum post. Warm a small piece cf 
 inlay wax and roll it into a stick that will approximately fit the canal, leaving it a 
 little long. Lubricate the canal, and while the wax is still slightly plastic, work it 
 gradually into the canal. Soften the projecting end with a few blasts of warm air 
 and warm the crown and press it firmly into place. The wax squeezing out all 
 around will indicate that an accurate impression cf the root has been secured. Chill 
 the wax thoroughly and withdraw, then with a sharp knife trim off the surplus. 
 Invest in soft material with the crown downward, the wax post serving as a sprue 
 through which to cast the gold. Cast in the usual manner, using 22k. solder or 
 platinized-plate gold. Let the flask cool thoroughly before opening. Various 
 modifications cf this method can be made. A plate or a vulcanite tooth may be 
 used, in which case it is advisable to leave the lingual side of the root a little longer. 
 
 —Denial Brief. 
 
116 PRACTICAL MANUAL OF DENTAL CASTING 
 
 METHOD OF PRODUCING PERFECT MARGINS 
 
 By C. Kabell, Chicago, III. 
 
 The practical value of the cast filling, its ease of manipulation to the patient, 
 and its time-saving advantages are appealing to me as to everyone, and I employ 
 it wherever it shows a saving of time compared with the malleted filling, but I have 
 been forced to change my technique. 
 
 Instead of carefully trimming down all overhanging edges I leave a little surplus 
 over all margins and after setting and allowing the cement to harden fifteen or 
 thirty minutes, trim down the edges with gold finishing burs and repeated bur- 
 nishings. 
 
 In doing this care must always be taken that the tool rotates from gold to margin. 
 For example, if I finish an occlusal filling in a right lower molar I trim the labial 
 margin by running the engine the regulation way, from left to right, but reverse 
 the motion when working on the lingual margin and do not forget to lubricate burs 
 and burnishers with vaseline. 
 
 By these means I have succeeded in closing the margins perfectly as far as can 
 be determined by ocular and exploratory inspection. 
 
 This- sealing of margins is necessary in the light of our past experience with 
 cements of the consistency used in setting of inlays, which is the same as has been 
 employed for a few decades for setting crowns and bridge work. 
 
 I have removed very few crowns, etc., that did not greet me with that foul odor 
 that cement stores up in its pores, and I have more often than not seen decay re- 
 curring under even well-mixed cement fillings. 
 
 The thinner the cement the more easily is it washed out and cracks form that 
 invite decay. 
 
 In cases where the shrinkage and warping of the filling would be too great 
 to overcome by burnishing, I employ a different technique. 
 
 The gingival margin has always been the weakest part of a filling, showing 
 the greatest percentage of recurrence of decay, and it is also the vulnerable point of 
 inlays. As it is in most cases impossible to properly burnish gold to place between 
 the teeth, I help myself by beveling, giving the edge an angle of about 12f) degrees. 
 The corresponding gingival margin of the inlay will show a V-shaped form, 
 the outer edge of which I burnish inward and depend on the malleting to open it 
 sufficienth' to make it fit snugly. If, upon examination, I find any opening, I repeat, 
 and only after being certain of a perfect fit will I cement filling into place. — Items of 
 Interest. 
 
 THE CAST CLASP 
 
 By W. B. Caldwell, D.D.S., Hamilton, Ohio. 
 
 The cast clasp is the most accurate clasp that can be made. After se- 
 curing a perfect cast from a plaster impression, proceed to burnish No. 40 tin 
 around the teeth to be clasped, which will keep the wax from adhering to plaster 
 tooth, then take inlay wax and press around the tooth, carve to the desired shape, 
 then attach a small piece of wax for a lug, remove, place on sprue wire, and inve.st; 
 use regular clasp metal for casting. Cement clasps on case before setting up the 
 teeth, to hold them in position. 
 
 By using this method you will have a denture that, when inserted, will give a 
 very pleasing result; it will not spring, but will be absolutely firm. 
 
NUGGETS OF GOLD— INLAYS 
 
 By O. E. Lanphear, D.D.S., Paw Paw, Mich. 
 
 Our profession has more cause for thankfulness than any other. This we may 
 say reverently, with no spirit of boastfulness in our own strength, but with gratitude 
 to our Creator, who has blest us with the conditions and environments which have 
 enabled us to achieve so large a measure of well-being and happiness for our fellows. 
 To the members of our profession has been granted the inestimable pleasure of strik- 
 ing out in many new untried lines and carrying them to a high degree of excellence. 
 We are the heirs of the ages. We have had to pay some of the penalties co-existent 
 with the conditions in bygone civilization, and in the face of these difificulties, which 
 have called for strenuous vigor and effort, success has attended us and we possess 
 a fixed determination to wrest from the future the measure of success which is the 
 reward of the faithful. 
 
 Success in the dental art has reached a great altitude through the special effort 
 expended on the restoration of health and the mitigation of pain. These have been 
 the constant themes of the most fertile human brains of their time, the fruits of which 
 their possessors have laid unsparingly on the altar of human progress. Today our 
 fellow men pay tribute and respect to the profession built upon the results of our 
 unceasing labors. Practical and experienced clinicians have formulated a working 
 hypothesis, so necessary to permanent advancement in any art, and we point with 
 pride to the acumen displayed by our profession in working out the theories. While 
 much is accomplished by the practical clinician it is becoming more and more a 
 necessity to thoroughly understand the theory of all technical procedure, thus placing 
 the art as far as may be in the domain of exact science. 
 
 Our ranks include many expert manipulators in porcelain and gold, each having 
 contributed something to the sum of professional knowledge, in cavity preparation, 
 speed or permanency. Some few furnish records of systematic investigations with 
 basic data to aid in reducing the chances of failure to a minimum. Too many are 
 content to understand the "how," with no knowledge of the "?c'//v" of their methods. 
 This accursed professional apathy keeps many practitioners from attaining the front 
 rank and leaves them narrow. Let us be broad and liberal, discreet and discerning, 
 willing and capable in the service rendered. 
 
 For the past decade inlaid fillings have occupied a prominent place in our work. 
 Porcelain and gold have held the foremost places and we point with pride to our 
 successful operators who save time and important tissue by their expert knowledge 
 and scientific technique. While we pay marked deference to these men, many of us 
 allow our energies to wane and our ambitions to atrophy. \\'c should be able to use 
 the inlay methods where discretion demands, for the\- ciiua! 
 
 "Nature's brag, and must be shown 
 In courts, at feasts, and high solemnities, 
 Where most may wonder at the workmanship." 
 
 The dental art requires painstaking study and careful manipulation to obtain 
 ideal results in gold inlays. Trained discretion in the preservation of toolh suii- 
 stance is as great an aid to iiermancncy as extension for prevention or retention. 
 
118 PRACTICAL MANUAL OF DENTAL CASTING 
 
 In simple cavities the seat of the cavity should be flat and parallel to the plane 
 of the defective surface, while the walls should be nearly at right angles to this and 
 slightly divergent. In compound cavities, lateral retention is secured by frictional 
 planes, dovetail extension or pin projection, that will allow the model to be removed 
 without distortion. Any deviation from the desired planes, as pits, under cuts and 
 spherical depressions, should be filled to within one millimeter of the surface with 
 good cement, and carefully trimmed to allow of drawing. When this has set the 
 cavity is moistened and the apex of a warm wax cone is placed against the deepest 
 portion of the cavity and the remainder is pressed to place with the fingers. 
 
 In compound proximal cavities, a strip of linen, celluloid or dam should be drawn 
 tight at the gingival border, for it greatly facilitates the work, especially' in cases 
 extending below the gingival line. It forces the wax tightly against the cavity walls 
 and gives an approximate contour to a border which demands perfect carving. 
 
 The wax should be chilled and the excess removed with a sharp carver, leaving 
 the occlusal full; now heat this surface a little and ask the patient to bite. He is 
 then left to his own devices for a moment to allow him to give it a natural bite. 
 When the wax is chilled again and the articulation is accentuated by carving, the 
 approximal surface is given a full contour and a normal contact. Polish the surface 
 of the wax and remove cautiously with a firm point and a steady hand. Give the 
 model a critical examination and do not hesitate to return it to the cavity if there is 
 any possibility of distortion. If assured that the wax is a perfect prototype of the 
 filling insert a heated sprue pin in the axial plane of a convex surface. This will aid 
 the gold to go directly to its destination without marring the investment margins. 
 See that no pits remain at the union of the pin and the model. Place the bare end of 
 the sprue pin in the crucible former in a position that will bring the wax near the 
 bottom of the investment ring. Coat the wax with alcohol and immediately pro- 
 ceed to apply a thin mixture of the investment with a camel's hair brush, forcing the 
 investment along under the film of alcohol, thus excluding the air. Gradually force 
 this layer off with a thick mix of the investment, filling the ring with the same and 
 bring the model to its position in the ring. In five minutes, when the investment has 
 set enough to be firm, the sprue pin can be heated a little to soften the wax, and re- 
 moved with the crucible former on it. Now invert the case and place on the heater, 
 where it is slowly brought to the boiling point of the wax (75 C), when the wax 
 comes out. From this point, the heat may be carried up rapidly and some of the 
 carbon burned out. Do not carry the heat higher than necessary, as it has a tendency 
 to distort the space left by the vanished prototype. A liberal piece of gold is now 
 placed in the crucible formed in the investment, heated nearly to the boiling point; 
 when the force of the machine is applied it rushes down the sprue hole, forcing the 
 air through the thin and porous investment, filling the space left by the wax and 
 remaining there under the pressure of the machine until congealed, when it can be 
 cooled rapidly in water. The inlay may be pickled to remove the investment mate- 
 rial, the excess of gold cut away on the lathe and the surface given the desired polish. 
 Then try it in the cavity. Make sure of the borders and the little details which 
 insure the permanency of the inlay. When satisfied with the trial, remove the 
 inlay and cement to place with a rocking hand motion, aided by the mallet in most 
 cases. The cavity form must furnish the retention, leaving the cement to hold 
 the inlay in position and give thermal immunity'. The margin of the tooth should 
 be cut true and as nearly at right angles to the surface penetrated as the structure 
 of the tooth and the cavity outline will permit, then the inlay will butt the cavity 
 
NUGGETS OF GOLD—INLA YS 119 
 
 margin, forming an ideal joint. This joint siiould be absolutely Bush and well 
 burnished. The margins of inlays should be accessible for convenience in working. 
 Sharp angles at the cervico-buccal and lingual aspects of the approximo-occlusal 
 fillings should be avoided. In occlusal cavities, the outline of the cavity should 
 have rounded angles, to avoid the gold wearing away the corners in the investment 
 at the time of casting. The cavities with narrow necks are apt to show that parts 
 of the investment have been worn away leaving the inlay full at this point. It will 
 not go to place until the neck is narrowed at these points. 
 
 Let us bear in mind that while we have mentioned many of the salient points 
 in the technology of the cast gold inlay, which saves frail teeth and weak enamel walls, 
 relieves patients of many of the nerve-racking procedures incident to the placing 
 of the rubber dam, the condensation of foil and the tedious sitting, it alone does not 
 constitute professional success. The profession of skill, brilliancy, honor, social 
 position or the ability to get the nuggets of gold, do not spell success. It is the 
 frankness of expression, largeness of heart, flexibility of mind, accurate perception 
 of difficulties and true discrimination, that makes our continued, conscientious 
 services benefactions of the race, and bring to us the appellation — Success. 
 
 DISCUSSION 
 
 Dr. a. C. Runyan, South Haven, Mich.: I am not an expert on gold inlays but I believe that 
 they have their special place in dentistry. 
 
 I have done more or less of the inlay work both in porcelain and in gold. I find that, as the doctor 
 says, a great deal of the success depends upon technique, and the more that we take pains with these 
 little details the more successful will we be with the inlay fillings. 
 
 It is claimed there is no better filling than a cement filling, provided it does not wash or deteriorate, 
 or become eliminated by the secretions of the mouth. Now that we can protect them with gold inlays, 
 I think that they make a very much better filling than any other filling that we have, except the esthetic 
 clatm of inlay porcelain. Gold inlays are better than poor porcelain inlays. Porcelain fillings 
 have a great many faults. We cannot use them at times where we can use gold, because of their 
 friability; and I think for the back teeth there is no better filling than the gold inlay, properly put in. 
 
 Dr. Lani-heak: I wish there had been more discussion on this subject. 
 
 There were several important points that I wanted to see brought out in the discussion. I have 
 been interested in the work Dr. Price has been doing in regard to the shrinkage of the mold, and as 
 near as I can find out he shows a shrinkage of about 15-1000 of an inch, which would make quite a 
 deficiency in a filling. If we can get an investment that expands the space at the moment the gold is 
 cast, and there is a shrinkage of the gold, though it is under pressure, perhaps it will be nearer the ideal 
 filling. A good many operators have used the matrix system to aid in overcoming this difficulty, 
 and they cast into the matrix, which becomes part of the inlay. The wax is built to perfect contour 
 and the casting process causes a very slight distortion. With this method, I think, there is nealry 
 perfect adaptation. 
 
120 PRACTICAL MANUAL OF DENTAL CASTING 
 
 LIMITATIONS AND USES OF THE GOLD INLAY 
 
 By H. M. Semans, A.M., D.D.S., Columbus, Ohio. 
 
 We have passed the experimental stage so far as the uses of the gold inlay are 
 concerned, and its limitations are controlled only by any other time-proven filling 
 material that will suit, in the judgment of the operator, the necessities of the case. 
 
 This subject does not exact from me arguments against the use of gold inlays, 
 rather I am expected to observe their already proven use while I try to show why and 
 how and where their use is called for in filling tooth cavities. Please keep in mind 
 that the older inlay, porcelain, at the hands of skillful operators has established itself 
 not only as our ideal esthetic filling material, but that it is recognized as a most excel- 
 lent permanent stopper, for thousands of such inlays are holding forth without carious 
 returns about their environments. Also keep in mind that manj^ more thousand 
 gold fillings are still today showing to us that they are capable of perfect sealment of 
 the cavities they occupy. And there are none of us but will give thanks to the 
 persistent efforts of those few enthusiasts fifty years ago who by such efforts gave us 
 amalgam, up to the present time our greatest posterior tooth preserver. Only a 
 few years ago we had no other thought than that these two, gold and amalgam, 
 placed properly against tooth w^alls, were par excellent, without limitation in the 
 proper use of each in its place; in fact, nothing else was used except gutta percha and 
 cement. But hold! like the crusaders of old I have found the talisman, cement 
 oxyphosphate of zinc, once a temporary make-shift for frail teeth, cheap fillings, 
 nervous, sickly patients, stopper of dressings, scorned by all as a permanent filling 
 material, except by the occasional few who recognized an esthetic worth to it, 
 even though constantly replaced. 
 
 It is hard to tell whether it was the solid block inlay idea of itself, or else some- 
 thing to help cement to be retained in a cavity, that has brought about inlaying of 
 cavities; probably the groping about and working out of both ideas. However, 
 today we accept the fact that inlays without oxyphosphate of zinc are as impossible 
 as moon beams at high noon. 
 
 First, then, where are gold inlays uncalled for? In all cavities unlined with 
 oxyphosphate of zinc. We all know that, only let us always keep it in mind. Next, 
 in all the six anterior teeth which will warrant porcelain inlays, chemical porcelain 
 cement, and gold fillings. We are now occasionally hearing the remark that porce- 
 lain inlaying has had its day. Yes, some kinds of porcelain inlaying has had its day, 
 and most of us, no doubt, have helped some of our own and others' porcelain inlays 
 to have their day, with a sigh and a-lack-a-day. But porcelain inlaying has improved 
 so greatly, and bad results have taught us so thoroughly, that we know anterior 
 tooth cavities which allow good thick edge approach of the inlay, where necessary, 
 can be, and are, effectively and beautifully filled with baked porcelain. Chemical 
 porcelain cements, while yet in an experimental stage, are showing, under wise and 
 careful selection of the place, some very good results. All small cavities in anterior 
 teeth which are not conspicuous and in manj' cases large proximal cavities which are 
 more or less inconspicuous, do not call for the gold inlay. It is still good practice to 
 fill such cavities with gold in the good old-fashioned way. The wide wedging and broad 
 cutting away of tooth structure for inlays is not warranted. It would seem, then, 
 that I have very nearly eliminated the gold inlay for the six anterior teeth; especially 
 for esthetic reasons, they should not be used, if possible to avoid doing so. Yet 
 under certain conditions a thin frail tooth, not having a great amount of labial sur- 
 
LIMITATIONS AND USES OF THE GOLD INLAY 121 
 
 face involved might wtxrrant a gold inla\', with iridio-platinum pin and [jrojier lingual 
 preparation brace against stress and strain. We all see mouths with teeth more or 
 less shortened, incisive ends badly worn down, the dentine between the enamel 
 layers of hard to soft decay always connecting up with proximal cavities or leaking 
 fillings; gold inlays indicated there? Yes, many times. Yet, ideally, what about the 
 jacket porcelain crown? 
 
 The gold inlay with porcelain, baked or inlaid into it, as ad\-ocated lately, may 
 work out to be a most excellent combination for anterior and some posterior restora- 
 tions; if so, then to that extent do we remove a limitation. 
 
 Posteriorly, gold inlays are almost unlimited. The cost of a filling of course is a 
 tremendous factor in our work, so I must immediately qualify that statement. 
 Amalgam can be so quickly inlaid in almost all posterior cavities, and made very 
 effective, so that it removes the necessity of gold alone as a posterior inlay. But we 
 must remember that it is amalgam's cheapness over gold that gives it its great ad- 
 vantage. Laying aside wax fillings for leisure hour casting, or laboratory assistant 
 casting, and the use of impression material with Price's stone cement models for 
 subsequent filling and casting has given us great consei'vation of time. The ease with 
 which amalgam is manipulated as against the labor and time taken to mallet in a 
 posterior gold filling has cost almost all users of amalgam enough money to ha\'e 
 bought and almost maintained that coveted automobile, or given an occasional trip 
 abroad. In the minds of many dentists, gold malleted fillings used in the posterior 
 teeth have become ancient history. Yet the gold filling can still and should be still 
 used in most of the pit and fissure cavities. On the other hand, we can average up 
 better contour and contact points with the gold inlay; our grooves, cusps, fossae and 
 ridges can be perfect reproductions; the restoration of all frail and extensively 
 decayed teeth is now almost universal; while as for ease and comfort to both 
 patient and operator, there is no comparison. Gold inlaying, then, in posterior 
 teeth, has wonderfully enlarged our field for better restoration. 
 
 We are constantly being told today that there is but one thing that stands in the 
 way of inlays as our ideal fillings, and that is the always possible dissolution of the 
 cement. This objection can be overcome in several ways. First, prepare the 
 cavities right and obtain a correct inlay; second, set the inlay as Dr. Taggart tells us, 
 with first a rocking motion so as to flow or rock out all the cement possible, followed 
 immediately with firm, steady pressure for twenty or more minutes. A good inlay 
 in a properly prepared cavity should almost, if not quite, eliminate the edge difficulty. 
 But if it does not, and it often does not, then finishing bur burnishers will spin the 
 gold over the margins. Lately we have been told that it is well to trumpet or be\-el 
 out more than we used to do, and this seems to be good advice. Our gold will 
 burnish out or spin out under the dull bladed burs, polishing to a smooth nicety with 
 disks and strips, as of old. xMso we have lately been ad\ised against the remo\-al of 
 quantities of our gold, both to economize and to give place for cement to get into to 
 help hold, following the line of argument that the closer our inlay walls approximate 
 the cavity walls, and the less cement we retain, the greater is the power of resistance; 
 and that sounds like most excellent advice and a scientific truth, for small and 
 medium sized inlays at least. 
 
 Pure gold seems to prove itself b^' all odds our best material, with 22k. plate a 
 second choice. Pure gold has proven itself to be so much stronger and better able 
 to withstand stress and strain than was expected of it. 
 
122 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Dr. Price's use of stone cement models to cast into has given us a splendid way 
 to obtain perfect proximo-cervical enamel edge adaptations, and ver>' much of the 
 trimming can be done before placing in the tooth. 
 
 We are all quite familiar with the lamentations from some dentists over the fear 
 that operators would soon lose their skill and cunning because of the fact that there 
 will be much abandonment of gold fillings in favor of the inlay. Feared as much 
 myself. But while delving lately into some old magazines, I was very much enter- 
 tained over the fears of the old regulars that the new fandangled material, cohesive 
 gold ("works just like putty"), as against the continued use of gold foil (non-cohesive) 
 would entirely eliminate skilfulness and manipulative ability from the dental pro- 
 fession. No, indeed, it is going to take great skill and manipulative ability to place 
 a perfect gold inlay, one that retains its seat immovably before cementing, except in 
 the direction of its desired withdrawal, one that closes of itself the margins, one that 
 will conserve the tooth for years, one that will restore the contact point so splendidly 
 that there will be no "meat spaces" with the terrible concurring ailments of gum and 
 alveolar tissue, one that will present perfect anatomical restorations of all its surfaces, 
 one that will protect enamel walls from fracture, in fact, one that will do that which 
 we most desire, save the tooth in an ideally practical manner. 
 
 THE GOLD INLAY 
 
 By J. V. Conzett, Dubuque, Iowa. 
 
 I want to commend the use of the gold inlay in its place, but it should be used 
 with discretion, and to be successful must receive the same careful painstaking at- 
 tention that is given to the gold filling. If this is done in every case, if the operator 
 strives to make every operation better than the last one, there will not be a decline 
 in his technical ability but he will go on from victory to victory, for "To him that 
 overcometh shall be given the crown of life." I can not close without urging the 
 profession, and particularly the younger members thereof, not to abandon the use 
 of gold foil as a filling material. The older men will not. They know the value of it. 
 But aside from its merits as a filling material, I know of nothing that will so perfect 
 the technical ability of the operative dentist than will the mastery of gold foil. 
 The man that can make a good gold filling has acquired a technique that will be of 
 the greatest assistance to him in the mastery of any other material, and other things 
 being equal, the man that has gained this technique will make a better operation 
 with any other material than one that has not acquired it. — Dental Review. 
 
 CASTING GOLD ON PORCELAIN 
 
 By E. Cunningham, Perry Sound, Can. 
 
 At last I have been successful in casting againsc porcelain without checking. 
 I use a flask, the dimensions of which are one and one-quarter inches in diameter 
 and the same height. After coating wax with silex and plaster, I fill balance of flask 
 with Broph3''s imperial investment compound and after drying I place in a coal stove 
 and leave till it is all red hot. Then it only takes a few minutes to melt gold and 
 force home, and as there is quite a body of investment around the tooth, it has not 
 time to cool before the gold comes in contact with it. I have made a four-tooth bridge 
 by this method and all facings were intact. — Dental Review. 
 
CROWN AND BRIDGE WORK 
 
 By J. H. Landry, D.D.S., New Orleans, La. 
 
 I have kept in touch with the best methods of crown and bridge work for twenty 
 years and can enter with perfect propriety upon a discussion of the exercise of 
 prudence in the application of the principles of crown work and bridging of spaces. 
 
 I do not propose to criticise or pass judgment upon methods that are freely 
 used by ethers. 
 
 The very minutest detail of mechanical construction will not be given, feeling 
 such to be unnecessary and I will deal with the broad underlying principles that 
 govern the attachment of a foreign substance to a root in the mouth as a substitute 
 fo" the lost crown, and the attachment of one tooth to another to support substitutes 
 for the missing ones, calling upon them to perform duties belonging to the full mem- 
 brane. 
 
 The e.Kperience and success of so many years has given this class of work the 
 acknowledged right to be considered among the most useful and reputable operations 
 of today; but the question arises, what has been the effect of its introduction to the 
 dental profession for good or evil? Like most all advanced methods, its benefits up 
 to the present time have been in restoring and preserving roots and broken down 
 crowns of teeth that would otherwise have been lost, thereby improving the power 
 of mastication, prolonging life and health. 
 
 How many times has there been a loss cf good roots and teeth through improper 
 attachment for the purpose of withstanding a strain they were unable to bear, by 
 injudicious fit — or badly fitting bands, causing irritation of the peridental mem- 
 brane? 
 
 A perfect crown must provide: 
 
 Firstly — A natural appearance if for the anterior teeth. 
 
 Secondly — A Richmond or preferably a crescent band to guard against splitting 
 weak roots. 
 
 Thirdly — The fit should be perfect so there can be no dislodgment. 
 
 Fourthly — To preserve the interproximate spaces and guard against all irritation. 
 
 Bridge work embodies all the foregoing dangers, increased proportionately to 
 the greater strain it is called upon to bear. 
 
 The collection of particles of food or other decomposable matter between the 
 ridge or under the gum may be avoided by making the surfaces and interspaces 
 self-cleansing. 
 
 The Logan, Bonwill, Howe, Davis, White and all other porcelain crowns that 
 are used have certainly the advantage of a more natural appearance for the anterior 
 teeth, over a plate tooth backed by metal. Of the ready-made crown I consider the 
 Logan less desirable owing to the shape, size and weakness of its pin, which has been 
 the cause of many split roots. 
 
 Noting the value placed upon a band for the security of the crown to root for 
 so many years, is gradually passing to a crescent or no band at all, because we hear 
 on all sides, "keep the neck of the teeth free from deposit of calculus or anything 
 that might irritate the gums," and in the same breath we are told to "pass the bands 
 up well under the free margin of the gum, regardless of such irritation." 
 
124 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Dr. E. Palmly Brown was the one who brought before the profession the system 
 of porcelain bridges, anchored with gold fillings, malleted about a bar extending into 
 the tooth. 
 
 Now the dental profession is greatly indebted to Dr. Taggart for his methods of 
 casting gold inlays and for the attachment of crowns and bridges that will save the 
 necessity of sacrificing the whole structure of many good teeth for bridging. 
 
 I very seldom use a band any more; it is unsightly, unnecessary, and with a 
 good pin you will get all the strength wanted, as all the force is outward. Sometimes 
 a band is necessary in a lower tooth where recession of the gums has left space for a 
 very short pin to be used and a good sized band can be used and not be seen. 
 
 In preparing roots for crowns I always seal the apex before reaming canal for 
 the reception of a pin and much future trouble will be avoided. 
 
 The dowel should be made of platinum and iridium wire only, all other kinds 
 are not safe if subjected to much heat. 
 
 Before crowning a tooth always devitalize. Should pyorrhea alveolaris develop 
 after a few fears in that mouth, those teeth will be free from the disease while one 
 sound one after another will be lost unless they are carefully treated. 
 
 I never take an impression for crowning of the anterior teeth; my patients' 
 mouths are my true models, and besides saves lots of time. Get size and shade of 
 facing ready before the appointed time of patient. 
 
 After reducing the root to the desired shape, take No. 33 gauge pure gold and 
 burnish to the root, leaving it a little overlapping in lingual portion to burnish over 
 root that will take the shape of a crescent band. Should you desire a large crescent 
 band, fit one and solder to pure gold before burnishing same over root, then punch 
 hole through plate and push pin to place, remove and solder (the pin having been 
 previously closely fitted to the canal), replace same on root, reburnish to water tight 
 joint and then trim to fit periphery of root. Grind facing to fit, back it up with No. 
 33 gauge gold, wax and attach the cap in mouth, remove crown, finish waxing as you 
 want it, box cutting edge and sides, invest and solder. When polished you have a 
 crown which fits perfectly over entire root and in cementing to place a thin film of 
 cement will be caught between the attachment but not enough to weaken the strength 
 of your crown. An open-faced crown is not a good anchorage for a bridge, for the 
 attachment to be any way weak will cause a failure. 
 
 It is almost impossible to lay down any set rules to follow, but I will mention a 
 few cases where a bridge will do good service. In making a bridge of twelve or 
 fourteen teeth it is necessary to have not less than four good teeth or roots, including 
 the two cuspids and two solidly set molars, that will carry a bridge for good service. 
 In this case the cuspids should be cut off and crescent crowns used, the molars should 
 be devitalized and two gold caps made for the abutment. 
 
 In case where right central and lateral are missing, left lateral and first and second 
 bicuspid out, I would make that bridge in two pieces by using right cuspid and left 
 central to carry right central and lateral, left cuspid and first molar to carry two left 
 bicuspids and lateral. In all cases a good bridge can be made from a cuspid to a 
 third molar. The two centrals will carry the two laterals and the laterals the two 
 centrals, and so on. A loose root, if properly treated, will get firm and strong again. 
 I will now touch lightly upon an important part to consider. In trimming molar 
 teeth you should always have in mind what the shape of the tooth would be if cut 
 across below the margin of the gum. The barrel shape entirely taken off to nearly 
 one-sixteenth of an inch below the gum line leaving the sides of the tooth parallel 
 
CROWN AND BRIDGE WORK 125 
 
 so that the band will hug the tooth tightly. Take a lower first molar. The buccal 
 side swells out very great, but the anterior surface not so much. After this tooth has 
 been properly shaped it will be nearly square with the corners rounded. 
 
 In many cases after trimming the mesial and distal surfaces it will be necessary 
 to trim only the lingual side, as the tooth often leans over towards the tongue, the 
 band will pass over the enamel on buccal side and touch the tooth below gum margin. 
 
 The most difficult part to reach in trimming is the anterior surface of the lower 
 molar. If you will take notice, an upper molar, when prepared, is found to be 
 altogether different from the lower, being triangular in shape. This will sometimes 
 vary, the palatal root being as broad as the two buccal roots, but not very often. 
 A great deal must be cut from the mesial and distal surfaces of the posterior 
 teeth and very little from the buccal and palatal or lingual sides. The cusps 
 should be ground away, so a thick metal cusp can be placed on the band to insure a 
 strong bridge. 
 
 HOLLOW CAST INLAYS 
 
 By W. S. Payson, Castine, Me. 
 
 In making a hollow cast inlay after the wax model is on the sprue, build up the 
 investment on the sprue side and let it harden; then, with a small drill in the engine, 
 drill out the back of the wax to the extent of the cavity wanted in the back of the 
 inlay, and finish the investment. 
 
 The first investment holds the wax firmly. The drill is better than a lancet for 
 cutting the wax. Particles of wax can be brushed away with a very fine brush. 
 
 A hollow inlay is more firmly held by the cement, and less gold is used. — Dental 
 Cosmos. 
 
 AN ANTERIOR CAST BRIDGE 
 
 By E. Cunningham, Perry Sound, Can. 
 
 Prepare roots for abutments and adjust platinum caps. Pass pins through the 
 caps and attach with solder. Take bite and impression; make model and grind 
 facings. Remove pins and caps from the model and enlarge pin holes so the case 
 will draw easily. Replace abutments on model and wax all facings in position, 
 attaching sprue so that gold will not flow direct against the porcelain. The case 
 is now rcad>- to be invested and cast. — Dental Review. 
 
 TO HOLLOW OUT WAX MODEL FOR GOLD INLAY 
 
 By S. T. Neill, Clinton, Mo. 
 
 An appliance costing a trifle can be made in a minute or two. Renioxe the 
 middle point from a hypodermic needle, hold it in Bunsen burner, and pull it out 
 with pliers; slip a foot of rubber tubing en er the large end of the needk', warm it in 
 the flame; suck gently with the lips on the tubing, while holding the warm point 
 against the excess wax of the model. Burn out wax in the needle point by holding 
 in the flame, and blowing through it. — Western Dental Journal. 
 
CASTING OF LARGE BRIDGES 
 
 By W. H. Hayden, D.D.S., Youngstown, Ohio 
 
 Editor The Dental Summary: 
 
 Dear Doctor: — I have read with much interest all that I have seen in any of the 
 magazines with regard to casting, especially bridge casting and other large cases. 
 In the February Summary I noticed a little item by Dr. J. G. Lane, of Philadelphia, 
 saying that large pieces should not be attempted because of shrinkage and consequent 
 misfit. 
 
 I have cast at least twenty bridges, of three to six teeth each, on two and three 
 abutments, and two eight-tooth pieces on four abutments, one having eight facings, 
 molding these in the mouth without impression or model, and I must say I never 
 inserted as fine-fitting bridges by any other method. 
 
 Here is an illustration that may help readers to understand: 
 
 Description: — Two dummies, porcelain faced, anchored by an inlay in occlusal approximal sur- 
 faces of second bicuspid, with post in root canal, and distally by an inlay in a compound mesial and 
 occlusal cavity in third molar. 
 
 Description: — Two dummies, porcelain faced, anchored by an inlay in occlusal 
 approximal surfaces of second bicuspid, with post in root canal, and distally by an 
 inlay in a compound mesial and occlusal cavity in third molar. 
 
 I would advise placing an iridio-platinum wire of generous size throughout such 
 pieces, and a very convenient method of doing that, in such cases as that shown, is 
 to bend the wire that forms the post in the bicuspid at right angles, and letting it 
 extend into the cavity in the molar, thereby greatly facilitating waxing-up and carv- 
 ing. It, of course, adds great strength to the finished piece. 
 
 It is needless to say that I use the Elgin casting appliance, and cast directly 
 onto the facings, the checking of a facing occurring so seldom as not to be taken into 
 consideration. 
 
MAKING A RICHMOND CROWN WITHOUT THE USE OF SOLDER— A 
 DETACHABLE PIN FACING 
 
 By T. C. Hutchinson, D.D.S., Decorah, Iowa 
 
 My principal reason for recommending this method of making a Richmond 
 crown to the profession is the simplicity of technic used. 
 
 A crown is a failure when it dees not protect the root to which it is fastened 
 against decay and breakage, when it is out of alignment, and when it is off color. 
 
 As is often the case, the dentist has not the shade required or the size needed in 
 an all-porcelain crown, so he uses the nearest one to it and cements it to place; so I 
 will endeavor to show that any porcelain facing or tooth can be used in the making 
 of this crown. I will, however, describe the use of a pin facing and its detachable 
 features. Other facings on the. market can be used, following the same method, 
 but in case of a Steele or Evslin, the facing is slipped off and the pin or the made-to- 
 order facing is lifted out from its wax seat. 
 
 Fig. 1. — Root trimmed and post in position, 
 ready for wax crown 
 
 Root Prepar.\tion — A banded root, when properly prepared is the surest and 
 safest method of saving a root from decay or breakage, and should be used in all 
 cases where the crown is to act as an abutment for a bridge, especially on single- 
 rooted teeth. 
 
 Great care should be used in making the band snug fitting and without irritation 
 to the soft tissues. A crown with coping of gold is much better than a poorly 
 fitted band. 
 
 The root should be trimmed below the gum line on labial and palatal surfaces 
 and left high in center; this prevents any backward or forward movement. 
 
128 PILA.CTICAL MANUAL OF DENTAL CASTING 
 
 Fig. 2 
 
 Fig. 3 
 
MAKING A RICHMOND CROWN WITHOUT THE USE OF SOLDER 129 
 
 Post — In reaming the canal out for the i)ost, make it just large enough so that 
 the post will fit in snugly. Use Irridio-platinum; let it extend out of root about 
 1-16 inch, bend the part that protrudes palatally; then remove and melt a little 
 solder to this point. The object of this is to insure a union of post to the cast gold. 
 Use 16k solder, as this is a low fusing solder and the cast gold striking it will cause it 
 to melt and thereby fuse with rest of crown. Note Fig. 1. 
 
 Facing — Select facing so as to match in color and size, and grind the cutting 
 edge, so as to have the wax and finally the gold protect it. Fit the gum edge ap- 
 proximally, just so it extends to the gum line; then oil the facing on all sides, the 
 pins especially, and select a mold on the Anterior Hutchinson Wax molding plate 
 and place facing in labial or buccal side of same; then pour the wax in hot, but not 
 too hot (wax which is too hot will absorb the oil which is to act as a lubricant and you 
 will have a time removing facing). Another method is to soften the wax over a 
 flame and press to fill mold with the end of a match or some other soft wood. After 
 this take a hot spatula and trim ofif the surplus wax; then remove. See Fig. 2. 
 
 Fig. 4 
 
 Cool the wax and then hold between finger and thumb (Fig. 3) and heat that 
 surface which is to be forced against the root and post. Be sure that the alignment is 
 right, then cool and remove. Take an old broach (smooth), (Fig. 4) heat it and run it 
 around the post to make it firm, and with a wax knife trim off the surplus wax around 
 root impression, also around the facing; then put in place in mouth to see that no dis- 
 tortion has taken place (Fig. 5). Then remove and take a piece of sticky wax, 
 soften and place against facing, removing it from its wax seat, and in the pin holes 
 place the carbon points, which being the same size as the pins will go to place without 
 any unnecessary forcing. Place the sprue at the thickest part of wax, invest and 
 cast; after this is done clean and burn out carbon, and cement to place. The carbon 
 points can be had from your dealers. 
 
 Very often we meet with cases where the bite is close and an ordinary facing is 
 too thick, or we may have a case of an extremely small tooth to crown. I take any 
 
130 PRACTICAL MANUAL OF DENTAL CASTING 
 
 vulcanite tooth, grind it down to fit so tiiat you do not depend upon pins for re- 
 tention, but make it just as you would an inlay for any single surface of a natural 
 tooth. Oil it as above; in fact, go through the same procedure as described for the 
 other facings. 
 
 DIRECTIONS FOR USING HUTCHINSON WAX MOLDING PLATES 
 
 Of all classes of work done bj' the dentist, there is none that gives so much com- 
 fort to the patient, and places the mouth in its most natural condition, as good fitting 
 crown or bridge work. There is no line of work that advertises ethically, or brings 
 the dentist in more cash than crown and bridge work. It has been the object of Dr. 
 Hutchinson, in devising the Hutchinson wax molding plates, to give the dentist an 
 easy means of accomplishing the best of results with the least amount of trouble. 
 The making of crowns and bridges with the Hutchinson system has made it possible 
 
 Fit;. :> 
 
 for the novice to do as good work as the most expert. In fact, it is a pleasure to do 
 this class of work. It not only does fast work, but it enables you to do artistic, 
 perfect-fitting dummy work. We also show you how to save gold; make lighter 
 bridge work, yet stronger than by the old method of soldering. Many mouths have 
 been ruined by having too heavy a bridge, which weighed down the abutting teeth, 
 causing them to elongate and loosen, and finally come out. By the aid of the plates, 
 you will find an incentive to talk crown and bridge work; you will do more of it, 
 and the price of the plates, you have made over and over again by having had them. 
 The dentist who is making the money today is he who has aiound him, in his office 
 equipment, instruments which will aid him to do work faster, better, and with less 
 worry to himself and patient. 
 
 The large plate contains one hundred and fifty-eight molds of the buccal and 
 occlusal surfaces of the bicuspids and molar teeth. 
 
 There are molds of bicuspids and molars singly, and in pairs, and also molds of 
 the bicuspids and molars united, so that you can get any desirable combination of 
 the posterior teeth that may be required for any case. 
 
 The molds are perfectly smooth, and the arrangement is so perfect that you have 
 an alignment of teeth which defy the most skilled carver. 
 
 We have carefully selected and arranged a large variety of sizes, both in length 
 of mold and also the width. 
 
MAKING A RICHMOND CROWN WITHOUT THE USE OF SOLDER 131 
 
 To reproduce a mold, be sure to oil the mold with a thin coat of 3-in-l oil; then 
 take a spoon and melt base plate wax and pour into mold; let it cool, then with 
 a hot spatula trim off the surplus wax, and remove from mold. 
 
 Now, having your wax teeth and your plaster model ready, you can bend this 
 wax dummy any way, and yet keep the forms, as made by the plate, perfect; you 
 then adapt it to the model, getting the contour, holding the articulator closed, press 
 the occlusion. You now trim off wax where needed, and take a minute amount of 
 oil of cajeput, soft gauze or the like, and smooth all surfaces, and then your dummy 
 is ready for the investment. 
 
 Be sure to use Hutchinson's wax or common base plate wax in conjunction with 
 the plate. It is necessary to have a pliable wax. It burns out as well as any inlay wax. 
 
 To make a hollow dummy, oil the mold to be used, then pour the wax in hot, and 
 while the wax is still in this heated liquid form, take a roll of absorbent cotton and 
 immergc into said mold. The hotter the wax, the quicker the cotton absorbs, and 
 the thinner will be the dummy. This will leave a uniform thickness of wax deposited 
 in the mold. You can add more wax on the occlusal surface, where thickness is re- 
 quired. Then remove from the mold and adapt to your model and obtain occlusion 
 as in solid dummies, then cast and solder a backing, or, if you don't want this hollow 
 dumm\-, but wish it solid, vet you don't want the weight that an all-solid dummv 
 
 will make, nor do you want the gold expense that this large dummy would necessitate. 
 Listen! I will shotv hoiv to get away from both of these objections and yet have a better 
 dummy and a stronger one than though it were solid, and still have an all-gold appear- 
 ing dummy. 
 
 First, select a mold that suits \'our case, then oil it and pour it full of hot wax 
 let cool and trim off the surplus, and then fit it to your model, trimming where 
 needed. You now have the size and form of the dummy, which is to be used for 
 your case. Second, oil the same mold again and pour the wax in hot, and with 
 absorbent cotton suck out most of the liquid wax. Third, take an old vulcanite 
 tooth having platinum pins (Fig. No. 1). Grind the surface off and bend the pins 
 back as in Fig. 2. Now set in the mold, which has the thin film of wax, and press 
 against the buccal surface, allowing for sufficient space approximately and occlusally; 
 you then melt wax hot and pour into mold, covering completely the porcelain, 
 leaving the pins exposed (Fig. 3). The object of having the pins exposed is to catch 
 in the investment material and hold the porcelain in position, while in the act of 
 burning out the wax and casting metal around it. If you were to cut this dummy 
 after casting, you would find a box effect, which has proven to be as strong as though 
 it were all solid metal. By using this method you are not only saving from one- 
 half to two-thirds the gold which a solid dummy would take, but you are making a 
 better dummy. One that is not over- weighted, not so ruinous to the teeth they are 
 fastened to, and consequently one which will have more lasting qualities. 
 
132 PRACTICAL MANUAL OF DENTAL CASTING 
 
 In a short time we will have for the market, porcelain cores with gold pins, so 
 that after casting there will be no perceptible means of knowing where the pins 
 protrude; until then you are at liberty to use the above means. 
 
 To make the backing for Steele facings, Evslin, or any detachable facing: 
 
 Place facing, after having ground to fit your case, and, having trimmed the cut- 
 ting edge, place in a mold which holds it approximately, and oil both the facing and 
 the mold, and pour the wax in quite hot and let it cool, and then trim wax off. You 
 then adapt it to your model and obtain occlusion and trim off the overlapping wax, 
 and leave enough wax for protection to the facing at the cutting edge; then with a 
 piece of sticky wax heat and place against facing, letting cool a second, and then, 
 in the case of a Steele or Evslin facing, slide off from wax. Place the sprue wire 
 on the palatal surface of wax and invest and cast. 
 
 When using the pin facing, fit the facing and bevel the cutting edge towards the 
 buccal surface, have the pins parallel, oil with 3-in-l oil, and place in mold, and pour 
 hot wax as above; let cool, trim off the surplus wax, adapt to model. You will note 
 how much easier it is to obtain protection for your facing with wax than it would be 
 with plate gold and solder. When you have perfected the fit to the model, trim off 
 overlapping wax as above, and use sticky wax to remove facing; then in the pin 
 holes place a piece of carbon point which is the exact size of the pins; invest and cast, 
 and after casting, burn out the carbon and then cement to place. 
 
 THE ANTERIOR PLATE AND ITS USE 
 
 This plate contains mostly molds of the anterior teeth of various sizes and shapes, 
 also molds of the full crown surface of bicuspid and molar teeth, and some extremely 
 large molds of the bicuspid and molar teeth for dummy purposes. It is especially 
 adapted where facings are to be used for crown work. There are so many features 
 about this plate in the making of crowns and dummies, that it will be used often 
 and become indispensable to the busy dentist. 
 
 THE CAST CLASP 
 
 W. B. Caldwell, D. D. S. 
 
 The cast clasp or band, used in retaining partial dentures, is found to be quite 
 satisfactory, made after the following method: First, moisten plaster tooth to 
 prevent wax from adhering, soften inlay wax and shape to desired thickness and 
 width; press around plaster tooth as far as clasp should extend; (also, in cases where 
 molars or bicuspids are to be clasped, and the articulation will permit, allow a spur 
 of wax to extend over into the sulcus) by so doing the clasp will not allow the plate 
 to settle, remove the wax after having shaped to suit the case, and invest as usual. 
 If a lug is desired, shape and unite with wax clasp, cast in one piece. 
 
 Another Method — Take a separate impression of tooth to be clasped, pour 
 a cast of plaster and XXX silex, equal parts, having cast prepared, melt inlay wax 
 and paint it on tooth over area to be covered by clasp, then invest without removing 
 wax from tooth. Care should be taken not to have clasp too thin as the cast metal 
 is more liable to break than clasp plate. A partial denture constructed with cast 
 clasps is very pleasing when inserted and quite practical, as there is no spring or 
 rocking to the denture. 
 
THE CAST ALUMINUM PLATE 
 By Robert Seymour, D.D.S., Philadelphia, Pa. 
 
 A plaster impression is taken of the case in the usual manner, and if a vacuum 
 chamber or relief is needed it is cut in the impression. This is then given a thin coat 
 of equal parts shellac and sandarac. When thoroughly dry an additional coat of 
 sandarac varnish, when quite dry a model of silex and plaster in the proportion of 
 
 No. 1 
 
 three of the former and one of the latter is made, always taking the precaution to 
 
 thoroughly soak the impression in water before running the model. (See cut No. 1.) 
 
 The silex I use for this purpose is a slightly coarser grade than that used for 
 
 inlay investment. This will give a harder model and still produce a smooth surface 
 
 No. 2 
 
134 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 on the casting. The plate is now waxed in the usual way, using tennax wax, as it is 
 thinner than the ordinary base plate. 
 
 The following additions will be noted in cut No. 2: 
 
 (a) — Plate spurred or scored. 
 
 (b) — Wax rim inside and out. 
 
 (c) — Gateways. 
 
 (d) — Sprue. 
 
 The sprue may be a No. 10 wire as shown in No. 2, but we prefer a short wax 
 sprue as shown in No. 3. 
 
 The plate being ready to invest, it is wise to place it in water and allow it to 
 absorb all it will take up. The case is now invested in the lower half the same as an 
 ordinary rubber case, bringing the investment to the edge of the wax. When this 
 is properly trimmed place a V-shaped groove encircling the model a short distance 
 
 ijimiiniuiiiii 
 
 No. 3 
 
 from the wax. This surface is now given a slight coat with oil and afterwards brush 
 lightly over with powdered soapstone; where the rugae surface has been transferred 
 by means of tin foil, as in the case shown, this tin should also be slightly oiled. 
 
 The second half of the flask is now placed in position filled with investment, 
 taking the precaution to shake it well to place; while this is still soft, a recess is cut 
 away in the central opening of the flask, until the short wax sprue is exposed; this 
 forms a crucible, for the subsequent melting of the metal. After the investment has 
 become hard the flask is subjected to dry heat for a few moments and separated; the 
 
THE CAST ALUMINUM PLATE 
 
 135 
 
 entire base plate of wax is readily removed and the only portion of wax left to be 
 burned out is that contained in the gateways and sprue. The case is now heated 
 on the furnace, and if any carbon is left on the surface of the model it can be readily 
 removed with the blow-pipe, as the entire surface is exposed and has a great advan- 
 tage over the closed flask method, as it is difficult to burn out such a large quantity 
 
 No. 4 
 
 of wax, and if this is not done the resulting cast is a failure. This is true in both 
 systems of casting where pressure is placed directly against the molten metal, or the 
 method of creating a vacuum. 
 
 When the case is hot, the upper part of the flask is again placed in position and 
 it will locate itself by means of the V-shaped depression, which was cut in the first 
 half, as the second half of the flask will have its counterpart. It also forms a guard 
 to prevent escape of the metal from the flask. 
 
 No. 
 
 No. 4 shows a crossed section of case at this stage. Tlic cup is now [ilaced 
 on the base of the machine, and the plunger cap placed firmly against it for the perma- 
 nent adjustment of the flask. The metal is now heated in the recess prepared for 
 it and when thoroughly melted the casting is made by packing moist asbestos fiber 
 
136 PRACTICAL MANUAL OF DENTAL CASTING 
 
 in the plunger cap of the machine and bringing it gently, but firmly, against the flask. 
 When the metal is cold, remove and cut away the gateways, leaving a small portion 
 remaining to help retain the rubber. The teeth are placed by means of the rubber 
 attachment. 
 
 The advantages of this method over the swaged plate are as follows: 
 
 1. Better adaptation, especially in undercut cases, as the case is cast direct 
 on the original model. 
 
 2. It is stronger, as a rim is carried not only on the outside edge of the plate 
 but also on the lingual surface a short distance from the teeth, the plate can also be 
 varied in thickness according to the strain. 
 
 3. Better anchorage for the teeth. 
 
 CASTING WAX 
 
 By T. C. Trigger, St. Thomas, Ont. 
 
 I have been using wax in various colors, and find that a rose tint is more trans- 
 parent than the green, which is a very essential point, as the marginal edges of the 
 cavity can be easily seen and the thickness of the wax can be determined, over-lapping 
 the marginal edges. To test the transparency of wax in various colors, I made thin 
 slices of equal thickness, and found that the rose-colored transmitted the light more 
 than the green, and the latter had to be cut very thin before any translucency could 
 be detected. — Dental Practice. 
 
 TO OVERCOME WEAKNESS OF A CAST GOLD BRIDGE 
 By W. J. Montgomery, Chicago, 111. 
 
 The brittleness of a cast gold bridge, due to the gold having been melted several 
 times, may be overcome by sprinkling mercury bichloride over the molten gold 
 immediately before casting. — Dental Brief. 
 
 COLLODION AS A SEPARATING MEDIUM 
 
 B. L. Worthley, Trenton, Mo., recommends collodion as a separating medium 
 for plaster impressions. A single coat, followed when dry by a little soapstone 
 rubbed over the impression, insures a clean parting and a smooth cast. — Dental Brief. 
 
THE IMPRESSION METHOD FOR INLAY WORK 
 
 By Henry W. Gillett, D.M.D., New York City 
 
 Since the introduction to dentists of gold casting by Dr. Taggart, a large part 
 of the dental profession has been concentrating its energies on the technique of the 
 casting process. As a result many variations have been evolved and published. 
 Prior to Dr. Taggart's introduction of the cast gold inlay, and antedating it by 
 a period sufficient for many of us to have adopted it for constant use in filling 
 cavities of medium and large size, we had the so-called matrix, or two-piece inlay. 
 
 When the cast inlay became possible, many operators who had been using the 
 matrix inlay found it easier to adapt to the new process the technique they were 
 already familiar with, than to develop the technique devised and so successfully 
 carried out by Dr. Taggart. 
 
 This so-called indirect, or impression method, has been repeatedly shown at 
 clinics, but I think it has not been as carefully described in our literature as it 
 deserves to be. Because of this belief, I was easily persuaded by your committee 
 to endeavor to present the merits of the process pursued by many successful 
 practitioners, especially as it gives me an opportunity to urge upon you the need 
 for, and the practicability of further advance in the perfection of this branch of 
 our work. 
 
 In order that we may understand each other, I desire to say at this poiht that 
 in speaking of gold inlays, or gold restorations, I have constantly in mind inlays 
 or restorations that fit the cavity margin accurately at all points, and that repro- 
 duce, as far as possible, the anatomical features of the parts they replace. In my 
 estimation inlays are failures if they show a cement line, lack approximal contact, 
 or present smooth occlusal surfaces. 
 
 The type of inlay I shall have most in mind is the ordinary occluso-approximal 
 of at least medium size, and from this up to complex restorations of whole 
 crowns. 
 
 In order to direct your attention at once to the points I desire to emphasize, 
 I will first enumerate some of the advantages which I believe accrue to the user of 
 the indirect inlay method, and will then, at the risk of being tiresome, endeavor 
 to describe in detail the steps of that method. 
 
 In conclusion I shall call to your attention the need for further advance in our 
 technique with regard to reproduction of occlusal surfaces. 
 
 Among the advantages which I personally find in the indirect method are 
 the following: 
 
 First — Superiority of fit and ability to use an alloyed, and consequently 
 harder gold without interfering with this superior fit. My usual choice for inlays 
 is an alloy of 971/^% pure gold and 2}/^% pure platinum. In cases where 
 greater hardness is desired, a higher percentage of platinum may be advantageously 
 used, but the 2^-^% alloy presents the advantage of sufficient ductility to permit 
 of the manipulation necessary to correct the errors accompanying the casting 
 process. 
 
138 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Second — The fact that we have in this process a hard die or cast of the cavity 
 on which this necessary correction can be done. 
 
 Third — The comfortable feeling that comes from the knowledge that if any- 
 thing goes wrong in the casting process itself where it is less easy to guard against 
 error, it is simple to start afresh without recalling the patient since the same die 
 and occlusion are at hand, and will ser\'e to make a dozen reproductions, if neces- 
 sary. 
 
 Fourth — Opportunity for more perfect carving of anatomical characteristics 
 in complex cases, and opportunity for finishing on the die, relieving the patient 
 of all finishing in the mouth, except the final burnishing of the margins, and the 
 slight polishing needed to remove the burnisher marks, thus conserving the time 
 of the patient. 
 
 Fifth — The removal to the laboratory bench of all the carving and finishing 
 at the hands of an assistant, and the consequent saving of the operator's time, 
 and the enlargement of his capacity to turn off work. 
 
 It has been for some years my expressed belief that the same care and atten- 
 tion to detail by either the direct or indirect process would produce similar results. 
 I have more recently come to feel that for all work except the conspicuously simple 
 cases, the indirect process will average to turn out better results; that, contrary 
 to the frequently expressed opinion the finished product is actually separated from 
 the cavity by fewer steps conducive to error than when the direct process is followed. 
 
 It is generally held by advocates of the direcc process that the indirect process 
 introduces two extra chances of error in the taking of the impression and the making 
 of the die. 
 
 Frequently we hear the claim made that the wax model exactly fits the cavity, 
 and that the gold casting reproduces it with absolute exactness. Neither of these 
 statements is generally true under the conditions necessary in our work. 
 
 The wax model necessarily changes in volume on being transferred from the 
 temperature of the mouth to that of the operating room and again on being in- 
 vested, the investment expands in the drying, wax burning and casting steps in a 
 ratio usually unknown to the workman; worse still it often appears to warp in 
 directions to which the workman has no clue except as supplied by the ill fit of 
 ihe casting. 
 
 it is my belief that the errors in the taking of cavity impressions and those in 
 making the die or duplicate of the cavity are more easily within the control of the 
 operator than are those liable to occur at nearly every other step of the casting 
 process — consequently I hold that when those two steps have been well performed 
 the operator can, by the aid of the resulting die, correct most of the errors occurring 
 in the subsequent steps and that his product will suffer less from errors influencing 
 its fit. In short, I contend that until such devices as Taggart's Wax Warmer and 
 Van Horn's device for maintaining body temperature during investment are ob- 
 tainable, until investments are better understood, and the errors in their manipu- 
 lation better guarded against, greater accuracy of fit will be possible by the in- 
 direct process than by the direct process, assuming similar conditions with regard 
 to care and skill in both instances. 
 
 The description of the steps which I am about to give you will show you that 
 there is greater chance of controlling error due to shrinkage of the impression 
 material when taking the cavity impression than there is of controlling that of the 
 wax model when made in the cavity because it can be better kept under pressure 
 
THE IMPRESSION METHOD TOR I NLA Y WORK 139 
 
 and some of its shrinkage compensated for in the earlier stages of its cooling by 
 forcing it further into the cavity. I think it will be conceded without much argu- 
 ment that we have amalgams from which dies may be made, which reproduce with 
 but very slight error the form indicated by the impression. 
 
 I will now attempt to describe in detail the steps of the process. 
 
 Cavity Preparation — The only special point to note as different from any inlay 
 cavity preparation is that in bell-shaped teeth it facilitates the work to cut back 
 the approximal contour making a flat approximal wall. This is not feasible in 
 many mesial cavities, but in distal cavities and others so placed that it will not 
 result in undue exposure of gold, it permits the bringing of the approximal margins 
 of inlays to the area of immunity with less sacrifice of tooth tissue and with 
 less discomfort for the patient than if the whole cavity is broadened to the line 
 of safety. 
 
 The impression of a cavity so prepared is less likely to be injured in withdrawal. 
 
 The Bite — The cavity being prepared, the next step in my own routine is to 
 get a wax bite with sufficient accuracy to permit placing the die in it in its correct 
 relations to the opposing and adjoining teeth. 
 
 If the die is inaccurately placed then the finished work will be wrong in con- 
 tour, or occlusion, or both. Sometimes I take also a small impression of opposing 
 teeth from which a cast is made for setting into the wax bite, and this is frequently 
 the more accurate procedure, as it usually provides a more perfect reproduction 
 of the opposing teeth than does the imprint in the wax. 
 
 In taking the wax bite, it is preferable to select a fairly hard wax so it will be 
 rigid when cold, and thus stand handling when placing the die without resulting 
 distortion. When taking the bite place the vaselined fingers of one hand each side 
 of the teeth containing the cavities so as to prevent lateral spreading of the wax, 
 and with the fingers of the other hand mold the wax first well into the cavities and 
 then flatten it till the depth of wax into which the opposing teeth are to bite is 
 reduced to the minimum required for the imprint of the desired portion of those 
 teeth. If there is a large surplus of wax it tends to flow out laterally when the 
 patient closes the teeth and thus distorts the impression of all the teeth included. 
 Some patients can materially assist by maintaining closure and molding the wax 
 against the teeth with the tongue while the operator does the same on the buccal 
 surface with the fingers. Sometimes it is well to chill the wax before removal, 
 but usually the surplus is sufficient to permit of its immediate removal without 
 distortion. 
 
 Taking the Impression^Several materials are in use. The writer prefers "Per- 
 fection Impression Material" because it softens at a low temperature, and quickly 
 becomes rigid on chilling. There are numerous variations of technique for getting 
 the impression, but underlying all the desirable ones are two general principles. 
 The first is that the impression material should always be so confined as to cause it 
 to be pressed directly against all parts of the cavity, particularly all margins. 
 The second is that the deeper part of the body of the material to be used should be 
 firmer than the surface so that it shall serve as a support to hold the softer parts up 
 to their required office, and as the whole mass is being cooled under pressure, to 
 force the softer parts closer, if they tend to contract away from the surfaces of 
 which an accurate imprint is desired. 
 
 This is accomplished in various ways. For short root ends, or for complex 
 restorations where a whole occlusal surface, or more than three surfaces of a tooth 
 
140 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 are included in the restoration, it is frequently desirable to fit a seamless band of 
 soft copper, or other metal, proceeding as if to fit a crown band except to have it a 
 little looser. When this is complete a block of impression material is formed to a 
 cone shape, having its tip just soft enough so as to avoid stickiness, and is then 
 pressed well home with the fingers, and kept under pressure while being cooled by 
 a stream of cold water, or better, a stream of compressed air at 20 to 30 or more 
 pounds' pressure. The latter plan is preferable to most patients because less 
 irritating to other teeth, and it is neater. 
 
 With the opposite extreme in cavities — the simple four-walled cavity, just a 
 stick of compound and an instrument to keep the gum awa^^ if it be needed, serves 
 better than any cup, as the solid base of the block of impression material takes the 
 place of the cup, and confines the softer portion. 
 
 For ordinary occluso-approximal cavities, cups made of German silver, 
 platinoid or the Roach Impression Cups are preferred by many, and serve admir- 
 ably. In using these cups it is important that after placing the material in the 
 cup the whole mass be cooled and the surface again softened so as to provide for 
 the hard base of material already referred to as essential to success. 
 
 I have left to the last the technique which I use most frequently, and which I 
 consider best adapted to making sure of a well defined imprint of all parts of the 
 cavity margin of occluso-approximal cavities extending to, or beyond the gum line. 
 
 Fig. 1 
 
 Fig. 1 — Typodont with prepared cavities and matri.x in position ready for 
 impression of one cavity. 
 
 Selecting a piece of platinoid of 32 or 34 gauge a little narrower than the length of 
 the crown of the tooth in hand, and longenough to permit of its being curved around 
 so as to cover its lateral sides 1-3 or 1-2 way, I proceed to form a matrix by trimming 
 the cervical side so as to impinge as little as possible on the gum, and usually cut 
 the middle of its occlusal side in a curve with its depression in the center. This 
 latter facilitates forcing the impression material well home as it does not have to 
 enter so deep a pocket, and the curving around the sides of the tooth helps to con- 
 fine the material and hold it to its work at the approximal margins. (Fig. l). 
 
 This matrix is generally held in place with wedges of absorbent cotton tucked 
 in between it and the adjoining tooth. If the shape of the tooth containing the 
 cavity is such that any bit of impression material overlapping beyond the cavity 
 margin is likely to be broken in the removal of the impression, then the matrix 
 is wedged snugly against the cavity margin so as to avoid having such a surplus. 
 
THE IMPRESSION METHOD FOR INLA Y WORK 141 
 
 In this case the cavity margin in the die is formed by the angle of junction of the 
 cavity wall and the matrix. If, on the other hand, the tooth shape is such as to 
 facilitate removal of impression and surplus intact, the matrix is wedged less 
 firmly into place so as to allow the impression material to extend over the cavity 
 margin and insure an imprint of the surface of the tooth adjacent to the cavity as 
 well as that of the margin itself. 
 
 The matrix being satisfactorily placed, a piece of impression material of appro- 
 priate size and shape is selected, and one end of it warmed and formed into a cone 
 shape. The cone may advantageously have been formed in advance by assistants, 
 thus conserving the operator's time. When softening and shaping the material, 
 it is helpful to keep the fingers lightly coated with vaseline. Having the cone of 
 compound softened with regard to its tip, and firm in its deeper parts, warm the 
 outer surface of its base enough so the corners will not interfere with exerting firm 
 pressure with the thumbs, or fingers. Oftentimes I then stick the base while thus 
 superficially softened onto whichever thumb or finger is the appropriate one for 
 the case, and so carry it to position, pressing it firmly to place and guiding or sup- 
 porting it with other fingers as may be necessary. Sometimes this forming of the 
 surplus with the fingers is necessary in order to insure removal of the matrix with 
 the impression. I keep pressure on the mass, and direct a stream of compressed 
 
 Fig. 2 Fig. 3 Fig. 4 
 
 Fig. 2 — Impression of cavity witli matrix in place. 
 
 Fig. 3 — Section of impression and plaster investment as it would stand when ready 
 
 for packing die. 
 Fig. 4 — Section of a packed die before removing impression and investment. 
 
 air against the material, thus quickly chilling it. If the cotton wedges are 
 accessible I usually remove them before unseating the impression. This is not 
 essential, but sometimes facilitates removal of the impression without liability to 
 fracture of important parts. 
 
 After the removal I immediately dry the impression with a stream of cold air, 
 and examine it carefully with a magnifying glass to make sure that the imprint of 
 the whole cavity and especially of the cavity margin is clear and accurate. (Fig. 2). 
 
 The patient is then dismissed, and the tray containing the impression, bite 
 and card bearing the necessary instructions is sent to the laboratory. If there are 
 no unusual conditions, I give the case no further thought until the patient arrives 
 for the next appointment, at which time the inla}' is tried in, its approximal and 
 occlusal relations tested and perfected, if necessary, and it is cemented in place. 
 
 In the laboratory the first step on receiving the tray is to inspect the relations 
 of the matrix to the cavity margin. If it has sprung away at all it is pressed ac- 
 curately to place, a very little stick wax applied to its exposed side, and a bit of 
 match stuck to it, the other end of the match being firmly imbedded in wax. 
 This provides a brace that holds the matrix in place, and avoids risk of distorting 
 
142 PRACTICAL MANUAL OF DENTAL CASTING 
 
 the impression, which would invariably follow if enough hot wax to hold the matrix 
 were to be applied directly to it while under pressure sufficient to retain it in 
 position. The hot wax would soften the material on the other side of the matrix, 
 and cause it to yield under the pressure. Numerous other ways may be equally 
 satisfactory, but this one is efficient and simple. 
 
 In the case of double compound cavities with two matrices in the impression 
 a ring of stiff wire slit on one side may be opened enough so as to exert the correct 
 amount of pressure when its ends are applied to the matrices, and a minimum of 
 wax added at the point of contact. 
 
 Investment of Impression — The matrix being secure a quantity of plaster is 
 mixed and at the moment when still soft enough to permit of so doing, and yet 
 not so soft as to flow in and cover it, the block of impression material and matrix 
 is pressed straight down into the plaster in such a manner as to leave the impression 
 exposed at the bottom of the opening in the plaster made by the passage of the 
 mass down through it. Careful examination is now made to see that no part of the 
 impression is covered with plaster, and any irregularity in the sides of the hole 
 or pit is filled in so as to avoid needless surplus in the die. 
 
 The result is a plaster block encasing the mass of impression material, except 
 with regard to the surface bearing the imprint of the cavity, which lies exposed at 
 the bottom of a hole of a depth equal to that desired for the die, and of a diameter 
 approximating that of the crown of the tooth involved. (Fig. 3). As soon as the 
 plaster has set the die may be packed. 
 
 Packing the Die — The hole in the plaster as described is the mold into which 
 amalgam is to be packed to form the die. Select anj' good amalgam in sufficient 
 quantity, and reduce it to a smooth plastic mass, such as is obtained by encasing 
 the mass resulting from triturating in a mortar in a sheet of rubber dam and gather- 
 ing the rubber tightly around it; or by dropping it into a rubber finger cot, and 
 gripping that closely around the mass, and rubbing the resulting knob vigorously 
 against the palm of the other hand. From the soft plastic mass thus obtained take 
 a small portion and with rounded points and burnishers of such size as are adapted 
 to the impression in hand work it carefully onto the surface of the impression, 
 placing it definitely into all inequalities and small depressions. 
 
 As the surface of the impression becornes covered, larger amalgam masses 
 may be used. Finally mallet force on a stick, which nearly closes the opening, 
 heavy pressure with the thumbs, or with a clamp and rubber block may be used to 
 consolidate the mass and expel surplus mercury. (Fig. 4). This work may be con- 
 veniently done late in the day and the amalgam allowed to set over night, but by 
 using a quick setting amalgam the time may be shortened. When the die is 
 removed from the impression, imperfections, if an}-, and surplus near the margins 
 are carefully removed, and the sides of the base are given a slightly tapering 
 shape away from the occlusal surface to facilitate seating and removal from the 
 plaster cast. Usually if one or more dies are to be seated in the same cast, or 
 if the base of the die is of a regular shape, a groove is cut across its bottom so as 
 to indicate its seat in the cast, when working on it at a later stage, without 
 need for trial. 
 
 The finished die is then carefully seated in the wax bite. In doing this observe 
 any portions of wax that interfere, and trim them away until the die is accurately 
 seated, depending upon the fit of such portions of the die as you know to be accurate 
 for your guide on this point, and ignoring all parts where surplus has been 
 
THE IMPRESSION METHOD FOR I NLA V WORK 
 
 143 
 
 removed. Having seated the die and waxed it to place, select an articulator, 
 preferably one provided with a lateral as well as a vertical hinge movement, and 
 filling with plaster the portions of the wax bite on the side containing the die, 
 mount it in the usual manner. If the imprint in the wax is to be used for repro- 
 ducing the opposing teeth, that may be filled also and the mounting completed 
 from the single mix of plaster. If a cast made from a separate impression is to be 
 used it may sometimes be seated in the wax bite at the same time with^the die 
 
 Fig. 5 
 Fig. 5 — Dies mounted in casts on articulator. One die lifted out to sliow its shape. 
 
 or it may be seated after the cast containing the die is run and mounted on the 
 articulator, and then attached to its articulator arm. When the wax has been 
 removed, and the surplus plaster dressed away, the result is a replica (Fig. 5) of the 
 conditions in the mouth that permits of free manipulation in carving the wax dupli- 
 cate with no hindrance from tongue, cheeks, saliva, overlapping and bleeding gums, 
 poor light, difficult access and nervous patient. The wax may be pressed into place 
 
 Fig. 6 
 Fis. 6— Example of pronounced cusp carving with round bottomed defective'sulci. 
 
144 PRACTICAL MANUAL OF DENTAL CASTING 
 
 with the aid of a matrix, and held under pressure until chilled, the die may be lifted 
 out and all margins exposed to close scrutiny under direct light, the carving 
 may proceed under the most favorable conditions, and at the hands of an assist- 
 ant, who can, with training and practice, easily produce results in that particular 
 line that excel in perfection the work of the average practitioner. For this branch 
 of the work young women often prove very valuable assistants. 
 
 The carving being complete, the process of casting does not vary from that 
 to be pursued in any casting, but when that step is completed the casting is tried 
 in the die, all imperfections interfering with seating carefully noted, and removed, 
 and the rough finishing performed first, then with burnisher and stone the margins 
 are fitted with careful exactness, and finally the inlay, or restoration, is polished 
 ready for insertion. 
 
 If the impression has been accurately taken, the die accurately made and 
 accurately seated, the resulting inlay should go to place without any manipulation, 
 and need only to be set in cement. If the contour or occlusion are not exactly 
 right, it is very easy, having the die at hand, to place it in that and grind and polish 
 as desired. The absence of grinding in the mouth is highly appreciated by most 
 patients. For doing the polishing, wheels made from ordinary typewriter, or 
 ink erasing rubber will be found most efficient. The ordinary round typewriter 
 eraser, costing four cents, will make four wheels five-eighths of an inch in diameter, 
 and when once used they become an indispensable adjunct in this work. 
 
 In complex restorations, where the whole top of a tooth is to be restored, the 
 indirect process reaches its fullest fruition. 
 
 It is a great satisfaction to be able to remove a gold shell crown, whose fit 
 is such that "sloppy" is a mild term for describing it, and on finding that the 
 previous shaping has left the lateral sides intact, to replace it with a hollow case 
 restoration supplying perfectly every requirement of a useful tooth and every 
 mechanical requirement as to support without the need of a band encircling the 
 root, to foster uncleanliness at the gum margin. 
 
 The men who can do in the mouth the required carving for such a case are 
 exceedingly rare, and when such a carving has been completed, with the expendi- 
 ture of much effort and patience, the risk of a slight mishap spoiling it, and the 
 difficulties of perfecting its fit in the mouth after it is cast, are considered, it is 
 removed from the list of feasible operations. 
 
 With the indirect process, however, such a restoration becomes almost as 
 readily feasible as the filling of an ordinary cavity, and the perfection of fit and 
 contour are sources of much satisfaction. 
 
 For complex restorations I frequently cast first a 24-karat base (Fig. 9) and fit 
 it to the die, and then cast on it the desired platinized alloy. This results in a very 
 perfectly fitting restoration since the pure gold base is easily manipulated on the 
 die, and any desired degree of hardness is obtainable with the alloyed gold used for 
 the rest of the casting. Usually my laboratory associate prefers to cast this 
 platinized top separately, having formed the wax over the pure gold base in its 
 seat on the die, and after so casting the top to solder the two together. (Fig. 10). In 
 that case he uses one of the well known solders for which the formula has been 
 given us by Dr. Fred A. Peeso. This solder matches so perfectly the color of a 
 2H% platinum alloy that when used to add a contact point, for instance, it can 
 not be detected, after being well polished. 
 
THE IMPRESSION METHOD FOR I NLA Y WORK 
 
 145 
 
 Fig. 7 (a) 
 
 Fip. 7 (b) 
 
 Fig. 7 — Cast from an orthodontia case of Dr. J. Lowe Young's showing uoinial rendition (a) 
 and condition after inlays were inserted a few years later. 
 
146 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 As this solder is so readily made, and so serviceable, I give the formula here 
 for the benefit of those not familiar with it; 
 
 Coin gold, 20k. solder; equal parts; fuse thoroughly on charcoal block and 
 roll thin. 
 
 The melting point of the solder is high enough so ordinary 22 k. solder may 
 readily be flowed on it. . ' 
 
 Such complex restorations are of great service in restoring badly broken down 
 molars, and with the addition of dowel pins they are frequently most serviceable 
 as bridge abutments. 
 
 These steps seem long in the description, but if proper assistance is at hand, 
 the process, as described, can be made to conserve the operator's time and enlarge 
 his earning capacit)'. Intelligent young women make very satisfactory assist- 
 ants for this work, and there is no part of it that they can not readily learn to 
 perform. 
 
 It remains to be stated that in the case of the practitioner who does all this 
 work with his own hands, there is doubt as to his turning out as much work by 
 following the steps as described as by the direct process, but it is my belief that 
 he will turn out work that will be of greater service to his patients. If that same 
 practitioner will, however, take the needful time to train an assistant to do the 
 routine steps that go on at the laboratory bench, he will find a material increase 
 in his efficiency. 
 
 Fig. 8 (a) 
 
 Fig. 8 (b) 
 
 Fig. S (a) 
 
 Fig. 8 (a) 
 
 Fig. 8 (b) 
 
 Fig. 8 (b) 
 
 Fig. 8 (b) 
 
 Fig. 8 — Illustrations of defective (a) and good (b) occliisa) surface carving by courtesy 
 Dr. J. Lowe Young and Tire Journal of the Allied Societies. 
 
 I now desire to call your attention to the need for further development of our 
 technique in the matter of restoration of the anatomical features of occlusal 
 surfaces. All the previous generations of dentists have been working by methods 
 that did not permit, within the bounds of reasonable effort on the part of the 
 operator, or of reasonable endurance on the part of the patient, of restoration of 
 the sulci, ridges, pits and grooves of occlusal surfaces, and even the restoration 
 of cusps was more often than not necessarily omitted. The resulting even-sur- 
 faced fillings served ordinarily to preserve the teeth, but not to preserve their full 
 
THE IMPRESSION METHOD FOR I NLA Y WORK 147 
 
 function. Those of you who do orthodontia realize the imperative need for cusp 
 restoration, and I doubt not that some of you have been asked why teeth with 
 large fillings served so poorly as masticators. 
 
 At this point, with your permission, I desire to quote a few sentences from an 
 unpublished paper by Dr. J. Lowe Young, read before the Academy of Dental 
 Science, and to be published in "The Journal of the Allied Societies :"* 
 
 "Did it ever occur to you that the orthodontist often works for years 
 to build up this normal occlusion, only to have it pulled down in a day by 
 ruthless extraction of a single tooth, or by the lack of restoration, by the 
 general practitioner, of cusp contour or approximal contact in making 
 fillings or inlays? 
 
 "It would seem, therefore, that the dentist must share the responsi- 
 bility of the orthodontist in emphasizing the importance of normal 
 occlusion by preserving it at all times, and at least by not destroying it. 
 
 "Hence, if the general practitioner is to properly restore any part 
 of the dental apparatus, he, like the orthodontist, must have in his mind's 
 eye the forms, surfaces and positions of the dental organs when normal. 
 
 "The value of proximate contact, the proper occlusion of each 
 cusp, the size of each fossa, and the direction of each sulcus, should be 
 known to him who aspires to restore or re-create these anatomical 
 forms." 
 
 For a time after the introduction of the cast inlay we were fully occupied in 
 coping with the difificulties of technique, and the problems of marginal fit and 
 anchorage. Now that these have become so well understood it behooves us to 
 
 Fig. 9 
 
 Fig. 9 — Die and 24K base for complex restoration of molar with over-lap ready to 
 
 be fitted to the die. 
 Fig. 10 — Die, 24K base, and a 2]/^ per cent platinized cast cusps for comple.x molar 
 restoration, the two latter ready for soldering together. 
 
 consider the fact that the casting process enables us to carve accurate reproductions 
 of any tooth surface with but little extra expenditure of time, and to restore 
 broken down tooth surfaces in a manner that shall leave them very close to normal 
 in efficiency. 
 
 I confess, with regret, that my own development in this line has been slow, 
 and I look back with sorrow to large occlusal inlays only two years old because 
 they were finished in the sweeping curves of our earlier technique. 
 
 Later on I reached the point of full cusp and sulcus reproduction (Fig. 6) and 
 realized that this meant progress, but cases that satisfied me six months ago 1 now 
 regard with regret because they were so carved that the bottoms of the sulci could 
 
 ♦Note. — See June 1912, The Journal of the Allied Societies. 
 
148 PRACTICAL MANUAL OF DENTAL CASTING 
 
 be polished, and this meant absence of the grooves and pits that belong there, 
 and which play an important part in the mastication of food. 
 
 The cusps of opposing teeth should never reach the bottoms of sulci. If they 
 do, there is much greater risk of splitting the tooth, and the absence of sharp 
 grooves at the bottoms of the sulci mean lessened masticating efificiency. Com- 
 pare Fig. 7 (a) and Fig. 7(b), also Fig. 8 (a) and Fig. 8 (b). Since we are now 
 readily able to supply them, there is no longer a legitimate excuse for the absence 
 of sulci, ridges, fossae, grooves and inclined planes from the occlusal surfaces of 
 our inlays and restorations. 
 
 They may be carved into the wax surfaces with appropriate instruments, and 
 gravers and burnishers of similar shape may be used for finishing if necessary, 
 but such a surface as is left by the casting process, when carefully performed, 
 with the anatomical features preserved, is of greater service to our patients than 
 polished surfaces with those features absent. 
 
 A realization of this fact and the logical action on our part means that in the 
 future a filled tooth will be as useful in performance of function as a sound tooth, 
 and that our work will have mounted to a higher plane of usefulness to the world. 
 
THE CAST GOLD INLAY 
 
 By C. G. Myers, D.D.S., Cleveland, Ohio. 
 
 At a dental meeting held in Texas several years ago, a dentist, in paying a high 
 compliment to another dentist of some local reputation, said that he could mallet 
 gold better than any man he ever knew. Though I cannot reproduce the word 
 mallet in the southern accent of this dentist, this expression had at the time a very 
 peculiar effect on me and I have remembered it very vividly ever since. 
 
 At this time I had been in the practice of dentistry but a short period and my 
 ideals had been barely established. But it occurred to me at the time that if a man's 
 ability to mallet small pieces of gold into a cavity of a tooth, and the necessary en- 
 durance to accomplish certain results along these lines constituted a great man in 
 any profession, my ideals would have to be very greatlj' altered. 
 
 My experience, after a number of years in the practice of dentistry, has been that 
 dentistry has meant the carrying out of too many minor and petty details so as to 
 test to the utmost one's nervous and physical powers. We find that the productive 
 life of a dentist is not so greac as that of men in other lines of business and profes- 
 sions, and this is wholly due to the fact that a dentist is subject to little petty annoy- 
 ances and details that have been wholly eliminated in other businesses. 
 
 When I attended dental college I was taught that the ideal point for condensing 
 cohesive gold was the needle point and that the serrated point was simply an aggre- 
 gation of needle points. We were taught at that time to use points with deep serra- 
 tions. We were also taught to use gold in very minute particles. A mallet weighing 
 eight to ten ounces was used in condensing these small particles of gold. 
 
 About this time I learned the use of non-cohesive or soft foil. This gold is 
 manipulated with hand pressure and by the wedging process. Some men were very 
 expert in the use of this form of gold and it not only saved teeth successfully, but it 
 was also a great time saver in certain classes of cavities. 
 
 After using deeply serrated points for several 3'ears those of shallower serrations 
 came into use. 
 
 About seventeen or eighteen years ago it occurred to me that if gold had the 
 property of cohesion, this property was not increased by the use of serrated points, 
 and I designed and used and continued to use for twelve years a perfectly smooth 
 point for filling teeth with cohesive gold. In facc, I used these smooth points for 
 seven years before anyone was found who filled teeth in this same way. It was only 
 after a paper had been prepared on this subject for the Ohio State Dental meeting 
 at Columbus, some years ago, that the discovery was made that the use of smooth 
 points had been advocated by some dentist twenty years before and this was abso- 
 lutely all that could be found in dental literature on the subject up to that time. 
 At the meeting at which this paper was to be presented there was in attendance Dr. 
 Bowman, of Columbus, and Dr. Heise, of Cincinnati, who were using smooth points 
 exclusively in manipulating cohesive gold, and strange to say, from that time to this 
 I have found no one pursuing this same line of practice. 
 
150 PRACTICAL MANUAL OF DENTAL CASTING 
 
 In filling some inaccessible cavities with the smooth point it was my practice 
 to burnish certain pieces of gold to the mass of filling and this in time became my 
 practice throughout the entire filling. 
 
 A double-end amalgam instrument was converted into a burnishing instrument 
 and all my fillings were introduced into the cavity by the burnishing process and with- 
 out the use of the mallet. 
 
 By the use of any of the above methods a great number of details had to be 
 perfectly carried out, for the slightest imperfection in almost any part of the work 
 meant an imperfect whole. 
 
 At a meeting of the Northern Ohio Dental Society, held in Cleveland shortly 
 after the discovery of the casting process by Dr. Taggart, Dr. Goslee, of Chicago, 
 read a very interesting paper on this subject and presented some beautiful specimens 
 of work. 
 
 The interest of the dentist, not only here, but all over the world, was aroused 
 by this wonderful discovery. To show to what an extent dentists were interested 
 in this process it is only necessary to state that within a very short time, after Dr. 
 Taggart had given this process to the profession, more than three hundred applica- 
 tions for patents on casting appliances were filed in the patent office. Personally, 
 nothing in dentistry ever appealed to me so strongly as did this process of Dr. Tag- 
 gart's. As it appeared to be the emancipation proclamation, not only to myself 
 but to all dentists, inasmuch as it eliminated detail and filling of tooth cavities. 
 In a crude way this method was adopted in my practice and from that day to this I 
 cannot recall a single instance where I have used gold in filling teeth by any of the 
 older methods. And were I compelled to again resort to the practice of placing gold 
 in cavities as we have been compelled to do in years past, filling teeth would be the 
 last business that would appeal to me. 
 
 Modern methods in all lines of business, professions and trades have eliminated 
 detail, but up to the past few years it was not thought possible to apply these modern 
 methods to dentistry, but with the advent of cast gold, as suggested by Dr. Taggart, 
 we have applied the process of elimination to our own profession. 
 
 Like all other innovations, cast gold fillings must run the gauntlet of the skeptic 
 and the knocker. About the time that I took up the practice of dentistry, crown 
 and bridge work was just coming into use and how it survived the many knocks it 
 received at that time is more than can be figured out. It was claimed that it was 
 unsanitary, unsightly and that the life of it was very limited. It was only when a 
 dentist found his practice drifting away from him that he began to retract some of 
 the harsh things he had said about it and added it as one of the means of extracting 
 a livelihood from his profession. The same will be true of the cast gold inlay as was 
 true of crown and bridge work. Some few will make a success of it and others will 
 not because it is an apparently easy process. 
 
 The process is in its infancy, and the appliances are crude, as compared to what 
 we will have in the future. Mistakes will be made, but through these mistakes 
 will come ultimate success. 
 
 Let us look at some of the features of elimination brought about by this work. 
 If it had nothing to recommend it beyond the fact that the teeth did not need separa- 
 tion, which I know from personal experience is a barbarous practice, it would need 
 nothing more than this to class it as an ideal method of restoring lost contours in 
 teeth. If it has eliminated the rubber dam, this alone would recommend it to the 
 
THE CAST GOLD INLAY 151 
 
 helpless victim whose sufferings in the application of this necessary adjunct to the 
 old methods of filling teeth were only equaled by the tortures of the inquisition. 
 
 Who has not suffered from the application of ligatures? Who has not suffered 
 from having a sore tooth malleted upon until every blow seemed worse than the 
 one previous and then the final tortures of the disks, stones and strips in the finishing 
 process until dentist and patient were about as nearly nervous wrecks as they pos- 
 sibly could be ? 
 
 No wonder dentistry and the dentist have been avoided. Even the dentist 
 avoids the dentist. You will find in the mouths of dentists as bad a state of affairs 
 existing as j^ou will find in an equal number of patients. But a different state of 
 affairs should exist today, through the methods we have of eliminating the sensation 
 in the tooth and all of the disagreeable features formerly connected with the malleting 
 of fillings in the teeth. 
 
 It will be but a short time when the demands of the patient will compel us all 
 to use more humane methods in our work. The physician today who would attempt 
 even minor operations without the use of some anesthetic would be classed as a 
 butcher. 
 
 In regard to the technique I will have very little to say. As I said before, it 
 is my impression that we have only a slight knowledge of the possibilities of this 
 work and our methods up to the present time are very crude. I feel that Dr. Price 
 with his pressure gauges and heat gauges is on the right track when it comes to 
 getting perfect and uniform results. 
 
 Up to the time the cast inlay was introduced, large restorations of the tooth were 
 very frequently made with amalgam or crowning. But it is now possible to save 
 teeth in a way that crowning has to be resorted to only on rare occasions. As at- 
 tachments for bridges where at one time extensive grinding of tooth structure was 
 necessary or gold was unnecessarily displayed, we can now use gold inlays and gold 
 overlays with pins running into the root canals as attachments for practically all 
 bridges, and the resulting work is not only practical but substantial and beautiful. 
 
 For a great many years all-gold crowns made by me were made after the method 
 suggested by Dr. J. Rollo Knapp, of New Orleans. The results obtained by this 
 method were perfect for this class of work, but the number of details to be carried 
 out was enough to discourage almost any beginner in this work. The same results 
 or better results are now obtained through our knowledge of casting and with no 
 more details than was required in the old shell crown. The construction of bridges 
 both gold and porcelain at one time meant a multitude of details in its construction, 
 but now with a few simple fittings a bridge constructed in wax with porcelain facings 
 in place, a bridge of any size can be made in one casting and we have never made such 
 perfect fitting plates as we have made by the casting process. 
 
 My method of making inlays consists in making a wax pattern of whatever is 
 to be reproduced, investing this in one of the different investing compounds furnished 
 by the dental supply houses, and using either centrifugal force or the vacuum for 
 forcing the gold into the matrix. In casting directly on porcelain there is no more 
 danger of checking the porcelain than there was by the use of the blow-pipe. It is 
 only necessary that the temperature of the investment and porcelain be raised to the 
 fusing point of the gold. 
 
 There are only two ways that the busy dentist can increase the income derived 
 from his practice, one is by increasing his fees and the other by increasing his output 
 
152 PRACTICAL MANUAL OF DENTAL CASTING 
 
 of work. It is very hard for a dentist with an established practice in a certain locality 
 to very greatly increase his fees, but it is easily possible for him to more than double 
 the amount of work turned out by using the casting process. 
 
 Now, I feel grateful to anyone who will put money in my pocket, and I feel 
 doubly grateful to anyone who will make my business cares lighter. I do not feel 
 that it would be fitting to close this paper without expressing my gratitude to Dr. 
 Taggart for all that the casting process has meant to me in the last few years. If I 
 am to continue in the practice of dentistry I can do so a greater number of years and 
 with greater profits each year than I could possibly have done under former methods. 
 Dr. Taggart is an originator and inventor and whereas he would like some substantial 
 returns as a result of his inventions, for the inventor is usually an erratic individual 
 and not a good business man, he would be more touched and pleased by the generous 
 praise and plaudits of those in his own profession. It is not for me to say whether 
 he is right in obtaining patents and trying to enforce legally what the law says is 
 due him, but I do know that the dentists have made a very poor show of appreciation 
 for the many benefits they have derived from what Dr. Taggart has taught them. 
 Whether casting was known to the Egyptians or Phoenicians cuts no figure in this 
 case. Dr. Taggart taught you what you know about this process and the chances 
 are if it had not been for the energy, the sleepless nights and the outlay of money that 
 Dr. Taggart has put in this work, we all would be plodding along in the same old rut. 
 
 DISCUSSION 
 
 Dr. L. E. Custer: Dr. Myers, after reviewing the malleted filling, first says it is quite unnecessary 
 to separate the teeth for an inlay. This is true in all proximal fillings in teeth in normal position. That 
 which was heretofore so hard to do is now one of the easiest parts of the work to produce — proximal 
 contours in inlays — and in addition it has been my practice to melt a pin-head sized piece of 22-in. 
 gold upon the contact point of the inlay, thus giving it a nicely curved surface of hard gold. That 
 which was so hard to secure, and at the same time so important to secure, in a malleted filling, is now 
 most easily produced in the inlay. 
 
 He correctly says that the rubber dam has been eliminated and with it the ligatures and the hours 
 of painful malleting. I would also add that half of the pain of cavity preparation has also been elim- 
 inated, for as a rule the preparation of a cavity for an inlay does not require so much cutting in the 
 dentine as for a malleted filling. A large part of the work can be done with the chisel and in the 
 enamel. With the malleted filling the time was when the operations were feats of endurance on the 
 part of the patient and dentist rather than of skill. But what a wonderful change has come about, 
 not only in the humane methods of technique but in the final result. For who can deny that a cemented 
 filling is not a better saver of teeth, a support rather than a strain upon frail walls, a preservative of 
 color and one of less thermal conducting property? 
 
 The essayist is too modest in what he says regarding gold crowns. In my own practice the inlay 
 has taken the place of fully 50 per cent, of the gold crowns formerly used. Sufficient time has now 
 elapsed to test the merits of the inlay, and viewed as a method of practice, I regard it as the most 
 revolutionizing step, all things considered, taken in dentistry in the past decade. 
 
 Dr. Henry Barnes, Cleveland: From the secretary I received a communication stating that I 
 have had a large experience in cast gold inlay work, and requesting that I should discuss the paper. 
 As a matter of fact, my experience has profited me nothing, for I have not succeeded to my satisfaction 
 in this field. 
 
 There are those who claim success and I have seen beautiful work by this method. Not suc- 
 ceeding myself I reasoned that the thing for me to do was the thing that I could best do, so if agreeable 
 to you I will briefly outline the method which I am using. 
 
 Before outlining the method, I desire to state that the cast method is in no wise condemned except 
 so far as I am personally interested. Several months ago Dr. Alexander, of North Carolina, called 
 upon me and outlined his method of packing moss fiber gold into a cavity, removing same, investing, 
 and then melting 22k. gold plate into the mass. My cavity preparation was such that most of the 
 gold remained in the cavity when attempting to remove the mass. However, thought was stimulated 
 
THE CAST GOLD INLA Y 153 
 
 and a gold matrix was placed within the cavity and this was filled with moss fiber gold (I now use 
 Ney's No. 4 soft gold foil with equal success and a saving of time), the whole removed from the cavity, 
 placed on the charcoal block and 22k. gold plate sweated into the mass, using the Lane blow-pipe and 
 the mouth as a bellows. A little practice with this method will surprise you in the rapidity with 
 which the work can be performed. Many cases can be made in the time required to make the wax 
 model, and the margins are assured if your technique has been correct. To shape the gold matrix of 
 .3-1000 pure gold, orange or other suitable wood is used, spatulate at one end and rectangled at the 
 other, also another stick is used shaped at one end exactly as your grandmother used to notch her 
 clothes pole; this serves to smooth matrix over the margins. Do not use metallic instruments on 
 matrix except the matrix forming instruments at the cervical margins. Use no Hux in sweating gold 
 into fiber. 
 
 Question: How do you get occlusion? Answer: Fill matri.x to occlusion and at the last use a 
 little flux over occlusal surface, including matri.x margin, then sweat 22k. gold plate over same. No 
 flux is used previous to this time. 
 
 Question: Do you condense the fiber gold? Answer: Only as much as can be done by the hand 
 with the wood point and to the anatomical form. If you fail to obtain a good cast inlay grind margins, 
 place matrix in cavity, cast in this, remove and sweat 22k. to cast and matrix. 
 
 Dr. H. C. Kenvon, Cleveland: From the tenor of Dr. Myer's paper we naturally conclude he 
 is an inlay enthusiast. And while I agree with much he has said, I cannot subscribe to all of it. 
 
 The first thing I want to take exception to is this: 
 
 "In a crude way this method was adopted in my practice and from that day to this I cannot recall 
 a single instance where I have used gold in filling teeth by any of the older methods, and were I com- 
 pelled to again resort to the practice of placing gold in cavities as we have been compelled to do in 
 years past, filling teeth would be the last business that would appeal to me. " 
 
 Unless his practice differs much from mine, I could not subscribe to such a statement as that. 
 I do not believe that all the cases requiring fillings can be filled with inlays more easily than with some 
 other kind of filling, especially the malleted gold filling. I believe there are some valuable things to 
 be gained from the malleted gold filling, put in under intelligent present-day methods. I do not think 
 that a statement like this should go unchallenged when we have young students in our audience who 
 are apt to take statements of essayists as authority rather than opinion. 
 
 I want to endorse fully what he says in regard to the use of the inlay in the place of the crown . 
 I do not believe the inlay comes to replace the malleted gold filling so much as it does some other 
 operations. I scarcely use the gold crown at all now except in cases of bridge work, where I think an 
 inlay may not be of sufficient strength to carry its portion of the stress. In such cases I still use the 
 gold crown because I can get stronger support. The essayist has called attention to some very impor- 
 tant points which ought to change the minds of those who are opposed to the gold inlay, and the cast 
 inlay in particular. One is the question of separation of teeth and the elimination of the rubber dam. 
 I cannot conceive of a sensible operator putting a large gold filling in a tooth that is subject to pyorrhea, 
 and I cannot conceive of a humane man putting a malleted filling in the mouth of a very sensitive, 
 nervous woman whose health is so poor that she cannot sit through such an operation without a case 
 of nervous exhaustion. And I think the doctor is timely in calling attention to the fact that we are 
 practicing humane dentistry as far as we know how. I think we ought to emphasize these methods, 
 and that is one of the strong arguments in favor of the inlay method of filling teeth. There is much 
 that might be said as to whether we should use the gold inlay or the malleted filling. A man might 
 better make a gold inlay than a poor filling. If he is going to leave the cracks there at all it is better 
 to have the cement in them than not. 
 
 Dr. J. V. CoNZETT, Dubuque, la.: I am diametrically opposed to some of the things that have 
 been said, and I very much deplore the fact that any man will get up before a society of scientific men 
 and say that he would not use a malleted filling in any place, because the inlay is a new process and the 
 gold filling is as old as dentistry itself. We know what the gold filling will do, we have great hopes of 
 what the inlay will accomplish, but I believe the man is very short-sighted who will cast aside the 
 gold filling. Things have come and things have gone which were going to take the place of the gold 
 filling, and from time to time men have advised us to throw away our pluggers; but the men who have 
 done so have afterward been found sneaking around in the ash pile hunting for them. I want to con- 
 demn just as severely as it is possible to condemn, any man who will advocate the placing of inlays 
 to the e.xclusion of gold fillings. 
 
 We deplore excessive extension for prevention. I advocate extension for prevention, but it should 
 not be abused. You and I have no business to cut away tissue that can be saved. It may be that 
 there are some men who ought to use cast gold inlays in every place, because they haven't the ability 
 
154 PRACTICAL MANUAL OF DENTAL CASTING 
 
 to acquire the technique to make gold fillings. I do not believe Dr. Myers is that kind of a man be- 
 cause I know of the success he has had with gold foil. 
 
 I want you to understand that I am not condemning the gold inlay. I said in my paper that 
 it had come to stay and I believe that it is going to have increasingly larger uses in restoring lost tooth 
 tissue. But I do believe that the man who is going to be a good operative dentist should be able to 
 use any material. It is a question of judgment; it is a question of technique; study the conditions 
 and then employ the method which will best meet the conditions and restore the tissue to the best 
 usefulness. 
 
 The doctor speaks of extracting a larger fee from our patients. I am glad I do not have to go out 
 and rope them in. They come in. I do not believe that the men who are practicing dentistry as it 
 should be practiced in these modern days have to go out after patients. I do not believe that the 
 patients come to us with fear and trembling. Just last week I had a lady come to me who had some 
 most abominable fillings in her teeth. If you had seen them you would have thought that the dentist 
 had used no cavity preparation whatever. ,She came to me in fear because of the experience she had 
 had. That lady was at lunch with my wife and she said it was a positive pleasure to have her teeth 
 filled in my office. I simply mean by that that because of our modern cavity preparation and the 
 modern methods of using instruments, it is not necessary to infiict the pain that was necessary years 
 ago. I should hate to be a dentist who would have to consume three or four hours in making a malleted 
 filling. I believe I would quit dentistry. I do believe when statements of this kind are made before 
 scientific bodies that we should get the other side. I believe that if we were to wipe out the necessity 
 for making the gold filling— that if the other methods were to take the place of the gold filling — it 
 would yet be best for us to practice the methods of the technique of the gold filling in our schools for the 
 perfecting of our pupils, because there is nothing that will so stimulate a student as the making and 
 perfecting of one's self in the filling of teeth with gold foil. 
 
A COMBINATION CAST CROWN 
 
 By O. H. Simpson, D.D.S., Dodge City, Kansas. 
 
 The all-cast crown has about as many objectionable features as either the seam- 
 less or cap and band crown, and it occurs to me that by combining the two processes 
 a much superior crown can be made. 
 
 In the all-cast crown it is practically impossible to get band bclcnv margin of 
 gum without an element of guess work; besides the band is apt to be clumsy and has 
 little or no tensile strength, which renders it unfit for support of bridge work. If 
 it were not for the fact that the seamless is less angular in form than the average 
 cap and band crown, and the absence of the solder line, there would never be a seam- 
 less crown used. 
 
 The ease with which the band can be adapted to the root makes up in a great 
 measure for the difficulty experienced in getting a graceful union between cap and 
 band. If any extensive reinforcing is done there is always more or less risk connected 
 with the process, and besides, it is difficult to get the thickness where it is most 
 desired, and the solder is apt to shift at any subsequent heating of the crown. 
 
 Fig.] 
 
 Fig. 2 
 
 Fig. 3 
 
 Most of the objectionable features can be overcome by cutting the band wide 
 enough to articulate edge of band with the opposing teeth. Place band on root, 
 festoon and adapt band to circumference of root. The band is readily articulated 
 with opposing teeth by having patient open and close the mouth a few times, thus 
 showing where to trim away the band. Be sure to leave band on the buccal surface 
 as long as the cusps of the adjoining teeth, as the distinct feature of this way of making 
 a crown is, that the band and cusps are made continuous, doing away with the solder 
 joint between cusps and band. The cusps can be made any length or form b\' cutting 
 notches in band and contouring with pliers, as is show'n in Fig. 1. 
 
 The band being longer it furnishes the operator a better opportunity to contour 
 than the old style of narrow band. Place band back on root and readapt to proximal 
 teeth. If it is a short stump, partly fill the open end of band with investment, 
 leaving room for sufficient thickness of wax to make cusps of desired thickness. 
 
150 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Finish filling the band with wax and have the patient bite down to get the articula- 
 tion. Carefully remove band, carve wax to correct tooth form, preserving in a 
 measure the articulating surfaces made by wax on opposing teeth. Fill upper end 
 of band after removing from the root with investment; insert sprue and proceed as 
 with any other casting. See Fig. 2. 
 
 I believe that the advantage of this way of constructing a crown over the short 
 band and cast cusps can readily be seen, as the gold used in casting is not always 
 the same color as the band, and if there is any slight defect in the casting process it is 
 less conspicuous, as it is underneath, instead of on the side. 
 
 I have found Fig. 3 particularly adapted to the support of bridge work on 
 lower cuspids where the patient objects to devitalization and Richmond crowns. 
 Prepare tooth as is shown in Fig. 4, cutting key seats and making sides as nearly 
 perpendicular as the case will permit. Make band open front and back, making it 
 
 Fig. 4 
 
 Fig. 5 
 
 Fig. 6 
 
 fit snug at anterior cervical and sides. Allow band to gap open slightly on the 
 lingual surface so that the keys and back will cast in one piece. Figure 5 shows 
 where I have sealed or melted wax keys and wax back on dry band before forcing 
 it down over prepared tooth. Wax will not adhere so readily to a moist band, hence 
 the precaution to attach the keys and back before forcing it over prepared tooth. 
 Carefully remove; insert sprue wherever it is indicated. 
 
 This band will greatly strengthen this form of bridge support, and is seldom 
 noticeable in conversation. With care the gold at the side and cutting edge can be 
 almost entirely concealed, as is illustrated in Fig. 3. Sometimes when the band is 
 not sufificiently heated, or is too badly oxidized, the cast portion fails to adhere to 
 band. For this reason, I advocate soldering the two together. The seam being so 
 perfect only a small quantity of solder is required. 
 
 Figure 6 illustrates side view of band Figure 3 before wax back and keys are 
 attached. 
 
DESCRIPTION OF AN INTERESTING CASE RESTORED BY ALL-PORCE- 
 LAIN BRIDGE AND BRIDGES UPON CAST BASES 
 
 By J. M. Thompson, D.D.S., Detroit, Mich. 
 
 During the last week of July, 1908, Miss A., a non-resident patient, presented 
 for restoration one of the worst cases of broken down roots (which had previously 
 supported their own and artificial crowns) that it has ever been my fortune to see. 
 The necessities of the case and the fact that it would be of interest to others did not 
 impress me sufficiently at first to warrant my making photos, models, etc., before 
 beginning the work. It was after having an X-Ray picture taken to locate a missing 
 cuspid that it impressed me as a remarkable case. 
 
 Figure 1, as presented here, is the X-Ray picture, and that it may be fully 
 understood, the reader will simply assume that he is looking from within outward, 
 and the description will be easily followed. 
 
 Reading from left to right, we find the first bicuspid the only natural crown in 
 the upper jaw. Letter "a" shows a broken down lateral root supporting a crown 
 
 Fig. 1 
 
 Fig. 
 
 held in jKJsition In- a twist of cotton. Letter "b" shows uncrupted cuspid resting 
 against apex of broken down central root. Letter "c" shows porcelain crown with 
 dowel extending into central root, around which is a roll of cotton which retained it in 
 the gum and tooth. Letter "d" shows right central, a devitalized tooth with an inlay 
 set in one side of the root for the purpose of properly shaping the end so that a porce- 
 lain jacket crown could be fitted, the crown being shown in position. Letter "e" 
 shows another porcelain crown also held in position by a twist of cotton, and letter 
 "f " another held in by the same method. It is needless to say that the patient was 
 somewhat of an expert in the wrapping of cotton around the dowels of these crowns, 
 and two of them were so securely fastened that considerable force was necessary 
 for their removal. 
 
158 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Figure 2 shows central incisor with cotton still in place, having been worn part 
 of a day before the root was removed. 
 
 A bridge of three teeth was first made for the lower jaw (right side), consisting 
 of a shell crown upon the third molar, a Davis crown upon a cast base, for the first 
 molar, with a diatoric molar supported between them. 
 
 Fig. 3 
 
 The root of the first molar was of peculiar type (see a, b, c and d, Fig. 3), having 
 three distinct roots with a perforation separating all three. The surface of the root 
 was ground to a plain surface and a Davis molar ground to fit the tooth as perfectly 
 as possible, and in shaping the porcelain molar it was necessary to place it in the 
 furnace to restore the glaze. A piece of No. 40 pure gold foil was then burnished 
 over the base of the crown and a post forced through the foil into the hole in the 
 crown. The soft wax was then placed in position and the crown pressed down 
 upon the root, the wax protruding through the perforation somewhat. This was 
 trimmed off and again adjusted, and then removed and the porcelain crown taken 
 away and a casting was made with gold foil in place. When completed, a very 
 thin line of gold was all that would give any evidence of its being used upon a 
 gold base. 
 
 Fig. 4 
 
 Fig. 5 
 
 A bridge for the upper jaw (right side) was then made, consisting of a Davis 
 crown cuspid upon a cast base, a gold shell for the first molar with two bicuspids 
 made by waxing the facings into place and forming dummies for casting and then 
 removing the facings and using lead pencil points to preserve the holes for the pins. 
 Thus we have a bridge without putting the facings through the fire. 
 
DESCRIPTION OF AN INTERESTING CASE 159 
 
 Next the lateral, "e," Fig. 1, was removed and a crown of suitable size, shape, 
 and color was placed in position. The porcelain jacket was then removed from "d" 
 Fig. 1, and the root prepared with a facer and a dowel of iridio-platinum set in 
 position to support one end of the bridge which was to be made. The lateral root, 
 "a," Fig. 1, which may be noticed as in the place of the missing cuspid, was then 
 prepared to support the other end of the bridge. 
 
 An impression was then taken and duplicate pins placed in the impression so 
 that the work could be made upon the model and so constructed that it would draw 
 with perfect ease. Four facings were then selected and waxed into position with 
 pink inlay wax upon a base of one-thousandth inch platinum, which had been pre- 
 viously burnished over the model. New porcelain was then placed upon the labial 
 surfaces of the facings at the cervical portion, also covering the platinum to quite an 
 extent. This was then placed before the door of the furnace and the wax melted 
 out, the porcelain holding the facings in their relative positions. No attempt was 
 made at forming a foundation at this time, as it was necessary to form a block of 
 four teeth before attaching it to either of the roots. 
 
 When they were removed from the furnace after the first baking they were 
 again adjusted to the model and pink gum body laid over the first baking and the 
 case again fired. Having secured the block, it was adjusted perfectly to the model, 
 and having made a platinum foundation upon each root in the mouth, the block was 
 then adjusted directly against the roots which were to support it. On account -of 
 possible change of shape, only one end was securely fastened at a time, and in ^s' 
 way a perfect fit was secured, and Figures 4and 5 show the case before and after the 
 work had been finished. 
 
RESTORATION OF BROKEN-DOWN ROOTS OF BICUSPIDS AND MOLARS 
 
 BY CAST METHOD 
 
 By A. W. McCullough, D.D.S., Pittsburg, Pa. 
 
 This method applies principally to bicuspids and molars, which are badly de- 
 cayed or broken down, or where by accident, one cusp has been broken off, the 
 break extending under the gum line, and a portion of tooth remaining. 
 
 First, after canals are placed in proper condition, pack space tightly 
 with some good temporary stopping, and allow to remain a day or two. 
 On removing, the margins will be exposed, and root can be shaped without injury to 
 surrounding tissues. The root should be shaped in most retentive form, leaving a 
 portion of remaining cusp for strength where possible. 
 
 k i 
 
 » 
 
 Figs. 1, 2, .3, 4 and .j 
 
 A post may be used in canal, but usually its being so short, an impression of 
 gold, making the whole in one, is advisable. After root is shaped, an impression 
 of root with inlay wax, extending into canals, properly trimmed to margins, is now 
 taken, invested and cast. 
 
 This assures perfect adaption to root. 
 
 Sprue is now cut off and cast, the part fitted into root, impression taken in 
 plaster or compound, model made and selected tooth built into place with inlay 
 wax; allowing it to extend over lingual cusp in sort of a hood shape to give strength 
 and retention, and then carving occlusion to articulation. 
 
 Tooth waxed in position, model is then trimmed as small as possible, and in- 
 vested again, put on fire and allowed to heat slowly, but to a high degree, so as to 
 assure uniting to cast base and less liability of fracture to porcelain, and then cast. 
 
 If model has been well shaped and smoothed, it will require but little polishing 
 and make a very strong, esthetic crown. 
 
SUBGINGIVAL AND ROOT CANAL RESTORATION IN CROWN WORK 
 
 By Edward C. Mills, D.D.S., Columbus, Ohio. 
 
 This method is offered to meet the requirements in those cases where the root 
 has become extensively destroyed by caries and disintegration, and the root canal 
 enlarged considerably beyond the requirement for inserting a dowel. To obtain free 
 exposure of the end of the root, tightly press away the soft tissue with gutta percha, 
 repeating the procedure at subsequent sittings, if necessary, as time expended at this 
 step will greatly facilitate accurate adaptation (Fig. 1). After removing debris 
 and decay, the sharp irregular edges should be carefully ground down with stones 
 and a carborundum root facer. If sufficient portion of the edges remains, and it is 
 desirable to use a banded dowel crown, proceed as follows: 
 
 Tube 
 
 Inlay 
 
 Tub. 
 
 Inlay 
 
 Tu.ll4j- 
 
 j-yy, 
 
 '^^/z 
 
 /'^/// 
 
 Irtla^ 
 
 Zrrjg:JEZ 
 
 I^estore the root by use of inlay wax or modeling compound, carefully trimming 
 and readjusting until the periphery of the root is re-established. Excess of moisture 
 is then removed and this core secured in position by powdered gum tragacanth. 
 
 Measurement for the band is now made by using Barbour's No. 3 Irish flax,* 
 the ends twisted until the thread is tightly adapted to the periphery of the root; 
 then with a sharp pointed surgeon's shears the thread is cut closely as possible to 
 the root. The advantage of the thread over a wire is the pliability of the former as 
 compared with the springiness of the latter. After cutting, the ends can be brought 
 
162 PRACTICAL MANUAL OF DENTAL CASTING 
 
 together and, if found to overlap, can be trimmed to a butt and an accurate measure- 
 ment is secured. From this make the band of sufficient width so as to permit 
 trimming, that a portion may extend to or sHghtly beyond the edge of the portion 
 restored by the core. 
 
 After selecting a round or square dowel of surplus length, take inlay platinum, 
 1-1000 thickness, and wrap closely around the pin at least twice, making a sleeve, 
 which is carefully slipped ofT and the exposed edge secured with a minute particle 
 of solder. The sleeve is now readjusted to the dowel, correct gauge obtained and, 
 with a bur of the exact size, the canal is extended to sufficient depth. The band is 
 now placed in position, the dowel in its platinum sleeve is coated with sufficient inlay 
 wax and pressed firmly to place, the wax is trimmed fhjsh with the band and all 
 carefully removed. The band is readily slipped off the wax and the dowel from its 
 sleeve, leaving the latter extruding through the wax model, as shown in Fig. 2. 
 
 Place a piece of graphite coated with thin plaster in the sleeve, invest and cast 
 (Fig. 3). After polishing, the excess length of sleeve is removed and the inlay thus 
 formed placed temporarily in position. With the band previously made, the cap is 
 completed in the usual manner, adapted to place on the root, perforated for the dowel 
 at the proper point, and the latter is pushed to its place. 
 
 To sustain the accurate relation of the dowel to the cap, a piece of modeling 
 compound is warmed and pressed against the projecting end of the dowel and surface 
 of the cap, cooled with a spray of water and carefully detached. If the cap and dowel 
 fail to remove, they are easily placed in their respective positions and secured by a 
 speck of wax. They are now invested, being careful that the interior of the cap is 
 filled with investment, and soldered (Fig. 4). 
 
 The cap with the dowel is now polished, and with the tubed inlay in position 
 in the root, it will be found to pass snugly to place. The tubed inlay is then cemented 
 permanently in position and, with the cap and dowel, the crown is completed in the 
 manner desired. 
 
 In cases where a band is not desired or unavailable, due to the condition of the 
 root, the inlay with the sleeve for the dowel is prepared at once and cemented to 
 place. 
 
 This method of restoration reduces the amount of cement to a minimum and 
 insures an accurate and determined position for the dowel. 
 
 *Irish flax is more economical and superior to dental floss in general use about the mouth, 
 can be obtained at any leather supply house. 
 
PORCELAIN AND GOLD INLAYS 
 
 By A. W. Starbuck, D.D.S., Denver, Colo. 
 Superintendent of Infirmary, Colorado College of Dental Surgery, Denver, Colorado. 
 
 In presenting these articles upon porcelain and cfold inlays, it is the desire of the 
 writer to furnish an outline of procedure which has proven very satisfactory in his 
 hands, as well as his many students'. He claims no originality to any of the methods, 
 rather it is a collection of the good ideas introduced and practiced by the eminent 
 porcelain and gold workers of the day. 
 
 The equipment recommended for porcelain inlays may be criticised by many 
 owing to its simplicity. But as this is intended more for the practitioner who has 
 been shut out from the use of porcelain owing to the extensive and e.xpensive equip- 
 ment supposed to be necessary, we will eliminate special instruments as much as 
 possible, thus showing the possibilities using the ordinary equipment of general 
 practice. 
 
 Fig. 1 
 
 Fig. 2 
 
 Fig. 3 
 
 CAVITY PREPAR.A.TION FOR PORCELAIN INLAYS 
 
 Generally speaking, cavities for porcelain inlays should be free from undercuts 
 in the direction in which the matrix is to be removed. There should be Hat seats at 
 right angles to all possible stress from mastication. All walls should be as nearly 
 as possible at right angles to the surface of the tooth. And all margins should be 
 sharp and not beveled. 
 
 The cavities here presented are a composite of the good points gleaned from a 
 careful study of a series of models sent the writer by about thirty of the prominent 
 porcelain men from different parts of the country. 
 
164 PRACTICAL MANUAL OF DENTAL CASTING 
 
 GINGIVAL CAVITIES 
 
 Gingival cavities should be extended only to include all the decayed area. In 
 doing this, endeavor to get an oval or kidney-shaped cavity as it is extremely difficult 
 to properly insert an inlay of circular outline. This extension is best accomplished 
 by the use of chisels and inverted cone burs. In this class of cavities there are 
 frequently several small pits on initial seats ( if decay. These are best united by the 
 use of small inverted cone burs. Then wi..h chisels break down the overhanging 
 enamel walls. This operation should be repeated, first using the inverted cone burs 
 (increasing the size each time), then the chisels until the cavity is extended to sound 
 margins and symmetrical outline. After the desired outline is reached, any under- 
 cuts that may be present should be cut away and the walls made parallel by the use 
 of square-end fissure burs, or better still, a similar-shaped plug finishing bur. 
 
 It is in these cavities we experience so much difficult}' in securing a proper color, 
 especially after the inlay has been cemented to place. Consequently great care 
 should be exercised in getting the proper alignment of the margins, also proper 
 
 Fig. 4 Fig. 5 
 
 depth to the cavity. This being an extremely sensitive portion of the tooth many 
 inlays are failures owing to o. lack in depth sufficient to give enough bulk to the 
 porcelain to exclude the influence of the cement, saying nothing of the strength of 
 the inlay. 
 
 Many will criticise the use of the parallel walls, citing the difficulty of burnishing 
 a matrix to a cavity of this nature. This objection you will find entirely done away 
 with in the methods suggested later for forming the matrix for this class of cavities. 
 The main objections to flaring walls are the lack of retention and the objectionable 
 change of color in the inlay from cement. The nearer you can get this cement wall 
 parallel to the line of vision the less it will change the color of the inlay. 
 
 A final inspection of the cavity should be made to make sure there are no 
 irregularities or small nicks in the margins. This is best accomplished with the use 
 of a lens. The marginal walls should be smooth, yet not polished, as cement will 
 not adhere properly to a polished surface. 
 
PORCELAIN AND GOLD INLAYS 16r> 
 
 The writer can not recommend too strongly the plan of seating the patient in a 
 normal position at this time and carefully viewing the walls of the cavity to make 
 sure they are parallel to the line of vision, as this is so essential to the appearance of 
 the inlay when set. How often have we viewed an inlay with pride when the patient 
 was tilted back in the chair, only to be disappointed even to the removal of the inlay 
 when the patient was standing or sitting in a normal position. 
 
 SIMPLE PROXIMAL CAVITIES 
 
 Among the many excellent ideas brought forth and taught by Dr. Black and his 
 disciples is one point which, if possible, is of greater value to the porcelain worker 
 than to the gold worker, and that is: 
 
 STUDY THE OCCLUSION 
 as the durability of an inlay depends largely upon the manner in which stress is 
 brought to bear upon it. This one thing should receive our first consideration. 
 
 Fig. 6 Fig. 7 
 
 In cases where there is excessive stress porcelain is contra-indicated. However, in 
 ca,ses with moderate or ordinary stress porcelain will prove satisfactory, provided 
 proper cavity preparation is considered and the inlay is carefully baked. 
 
 The patient should be requested to close the teeth, first, normally, then have him 
 move his jaws in such a manner that every peculiarity of occlusion at that particular 
 point can be carefully noted. Frequently what at first seemed a favorable case has 
 proved dangerous when considering the lateral movements of the jaws. Many such 
 cases may be improved by slight grinding of an angle of the tooth or the tip of a cusp 
 when this portion is slightly elongated. 
 
 In inlays where stress of mastication is a factor of consideration they should 
 always be removed in the direction from which such stress comes. There should also 
 be fiat seats antagonizing any force brought to bear from this direction. 
 
 Generally speaking, proximal cavities should be so prepared that there will be 
 no difficulty in removing the matrix where there is but slight separation. 
 
 Fortunately, the lingual wall is generally the weaker, consequently it is a less 
 sacrifice to cut away this wall to permit the easy removal of the matrix and this is 
 
166 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 the logical procedure in the upper incisors and cuspids (the teeth we are dealing with 
 mostly), unless we have an abnormal occlusion. 
 
 In preparing a single proximal cavity in an upper incisor, first break down the 
 weak enamel walls, using chisels or hatchet and hoe excavators. Then with smooth, 
 square-end fissure burs in the right angle entering from the lingual the cavity may 
 be formed. 
 
 The cavity should be slightly larger at the lingual than it is at the labial to 
 permit the removal of the matrix. The axial wall should be as nearly flat as possible 
 and parallel with the long axis of the tooth. The incisal and gingival walls should be 
 at right angles to this. These walls are formed with the sides of the bur, while the 
 square end forms a flat seat under the labial plate. Any imperfections following the 
 use of the bur may be remedied by the use of the hatchet and hoe excavators. All 
 margins should be made at right angles to the surface and should be sharp and well 
 defined. At this time the patient should be placed in a normal position and a close 
 inspection made of the labial margin to make sure it is parallel to the line of vision, 
 and if not it should be so altered as to remedy the trouble. 
 
 Fig. S 
 
 Fig. 9 
 
 Fig. 10 
 
 It is needless to say that all remaining decay should be removed. In case this 
 .should cause undercuts or pockets they may be filled with cement. 
 
 The important points for consideration are: First, the caviiy should be larger 
 at the lingual than at the labial; second, the axial wall should be flat; third, the incisal 
 and gingival walls should be at right angles to the axial wall; fourth, there should be a 
 flat seat under the labial plate; fifth, all margins should be at right angles to the sur- 
 face and not beveled; sixth, the labial wall should be so modified, if necessary, to make 
 it parallel to the line of vision. 
 
 In cases where the lingual wall is strong and the cavity is near the labial surface 
 the preparation may be so modified to permit the matrix being removed to the labial. 
 This would be permissible only in very small cavities and those caused by an over- 
 lapping tooth and then when it did not involve the lingual wall. 
 
PORCELAIN AND GOLD INLAYS 
 
 167 
 
 The preparation of a cavity in a lower incisor, regarding the manner of removing 
 the matrix, would depend largely upon the condition of the labial and lingual walls, 
 but it would be preferable to remove to the labial. 
 
 In cavities of this class there has been considerable criticism by many as to 
 whether porcelain was indicated in any case. However, time has proven that they 
 will stand, under proper conditions, even eciual to the average gold fillings. 
 
 Again, it is of the greatest importance to 
 
 STUDY THE OCCLUSION 
 
 This is something that should become a habit with every dentist. Very few 
 men even think of the occlusion until the patient goes to leave the chair and com- 
 
 Ki;4. II Fig. 12 Fig. 13 
 
 plains of the filling or crown being too high. By carefully observing the occlusion 
 on the start, it may prevent after disaster and possibly change the entire procedure. 
 
 In cases of an edge to edge bite and showing considerable wear, porcelain 
 should be used with great caution, if at all. While teeth with normal occlusion may 
 be filled with porcelain if due consideration is made of the preparation of the cavit>- 
 and the results will be permanent and serviceable. In ail cases we should endeavor 
 to get the maximum thickness of porcelain possible. The method used by some of 
 leaving the labial plate and building up the lingual plate only, at the incisal edge or 
 vice-versa, is a dangerous and frequently disastrous procedure. 
 
 The method of cutting away the labial plate, (Figs. 8, 9, 10), to a straight line 
 parallel with the long axis of the tooth and depending upon the depth of cavity and 
 parallel gingival and incisal walls upon the lingual, has merit in cases where the tooth 
 
 Fig. 14 
 
 is of considerable thickness labio-lingually and there is sufficient dcptii of cavity in 
 the direction of the pulp, but as a rule there is not sufiicient anchorage to withstand 
 the stress of mastication. The better method, and I think the one adopted by the 
 
168 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 best authorities, is to gain additional retention by extending the cavity on the incisal 
 edge, forming a step. 
 
 In shaping the labial margins, it is preferable to extend so all portions of the 
 margins will either be at right angles or parallel to the long axis of the tooth. For 
 example, if we had a tooth broken down as illustrated in Figure 11, it should be cut 
 away with a carborundum stone until the margin assumes lines illustrated in Fig. 
 12, rather than shaping it as illustrated in Fig. 1.3, or again in a more extreme case as 
 shown in Fig. 14, instead of simply smoothing the surface of the break, leaving the 
 general view as it is, it is preferable to form a series of steps as shown in Fig. 15. 
 A cavity thus prepared will show less and in many cases have increased retention. 
 The principal reason for such a procedure, however, is the fact that the fine line of 
 union takes on the appearance of a developmental groove, or a natural crack in the 
 
 Fig. 16 
 
 Fig. 17 
 
 Fig. 18 
 
 tooth and is hardly noticeable. An inlay that is a shade or two ofT in color will 
 hardly be noticeable, while a bias margin is noticeable even with a perfect match. 
 
 The m.atrix should be removed in the direction from which occlusal stress conies; 
 namely, to the lingual in the upper anterior teeth with normal occlusion. In all 
 cases there should be flat seats antagonizing any such stress. 
 
 In preparing cavity Figs. 8, 9, 10, the labial plate may be formed with a knife- 
 edge carborundum stone. The lingual plate is removed with chisels and hoe ex- 
 cavators; then with a smooth fissure bur extend and shape the gingival and incisal 
 walls of the cavity sufficiently to permit the easy removal of the matrix. The axial 
 wall should be flat and parallel with the long axis of the tooth and the gingival and 
 incisal walls at right angles to this. The junction between these walls should be a 
 well defined angle and not rounded as some advocate. With the end of the bur a 
 fiat seat is formed under the labial plate. Then remove any remaining decay and 
 carefully inspect all margins to make sure they are sharp and well defined. Finally, 
 .seat the patient in a natural position and carefully examine the labial wall to make 
 sure it is parallel to the line of vision from the cavo-surface angle inward. In other 
 
PORCELAIN AND GOLD INLAYS 
 
 169 
 
 words, only the cavo-surface angle should be in view. Especial attention should be 
 given to the gingivo-labial angle, as it is at this point we have a tendency to cut 
 insufficiently. A cavity of this nature is seldom indicated as it lacks sufficient 
 incisal retention if there is any great amount of stress. 
 
 The method preferable and generally used is one where additional incisal re- 
 tention is obtained by use of a step. 
 
 The main portion of the labial wall and the step are formed with a knife-edge 
 carborundum stone. It will be noticed in Fig. 16 that the gingival wall of the step 
 is not quite at right angles to the long axis of the tooth, but dips down slightly as 
 it approaches the axial wall of the step. This is necessary to afford retention from 
 dislodgment to the approximal as the fulcrum is at the cavo-surface angle of the 
 gingival-surface; hence, the inlay in the step moves incisally slightly, if dislodged. 
 
 Fig. 19 
 
 Fig. 20 
 
 Fig. 2] 
 
 By examining Fig. 17, it will be noticed that the line of the pulpal wall of the 
 step is broken, thus affording additional strength to the porcelain at this point. 
 This is formed with a small inverted cone bur held parallel to the long axis of the 
 tooth. The diameter of the step mesio-distally should be about two millimeters 
 ordinarily and about the same diameter inci.so-gingivally at the narrowest point; or, 
 in other words, should be of sufficient dimensions to give strength to the porcelain. 
 
 The main portion of the cavity is formed with a smooth fissure bur in the right 
 angle. Special attention should be given to the gingival wall to have it at right 
 angles to the long axis of the tooth, also to have a flat seat under the labial wall. 
 Many advocate grooving this seat near the axial wall, but this is a very dangerous 
 procedure as there is danger of cutting through the dentine to the enamel, which 
 would completely destroy the strength of the wall, as there is no strength to enamel 
 when not supported by dentine. Nor is a groove along the gingival necessar\' if that 
 wall is perfectly flat and at right angles to stress. 
 
 Again inspect all margins carefully to make sure they are smooth and sharp 
 and note the angle of the labial wall, especially the gingivo-labial angle in the main 
 portion of the cavity and the gingival wall of the step. 
 
170 PRACTICAL MANUAL OF DENTAL CASTING 
 
 If the labial wall is thin and lacks sufficient dentine to give it adequate strength, 
 there should be an additional step made inciso-gingivally upon the lingual surface. 
 
 This is formed with an inverted cone bur in the right angle and should extend 
 from the incisal step to the gingival seat. The step should be on an average about 
 one and one-half millimeters wide and a corresponding depth. Some authorities 
 advise a groove extending inciso-gingivally along this step, which has advantages in 
 many cases, but care should be taken to consider carefully the location and size of 
 the pulp in live teeth. 
 
 INCISAL RESTORATIONS 
 
 In considering cavities involving the incisal third of the six anterior teeth, it 
 might be well to divide them into two classes: First, fractures; second, atrophied 
 teeth. 
 
 In fractures, the teeth may be broken diagonally or almost at right angles to the 
 long axis of the tooth. In either case, the labial margins should be cut at right 
 angles to the long axis of the tooth. If the break does not involve both angles, as 
 in Fig. 22, the margin should be cut away as shown in Fig. 23, or if the fracture is 
 
 Fig. 22 Fig. 23 Fig. 24 
 
 at a greater angle, the surface may be stepped, as in Fig. 24. This method of prep- 
 aration will be much less conspicuous than wliere the margin is at an angle. 
 
 Porcelain "tips" are very disappointing in many cases, especially where they 
 involve the entire incisal edge. We may have a perfect match for the color before 
 cementing, and there may be no apparent change in the color of the porcelain after 
 cementing to place, but the shadow caused by the tip and cement will cause the re- 
 maining portion of the tooth to turn dark and be decidedly unsatisfactory during 
 ordinary conversation. If there is an approximal cavity which can be included in 
 the restoration, this trouble does not seem to appear. 
 
 In large cases, involving more than the incisal third, it is preferable to follow 
 the method suggested for badly atrophied teeth. 
 
 The retention for fracture cavities may be formed by cutting away the dentine 
 to a depth eciual to the extent of the fracture, as in Fig. 25, This extension for the 
 retention is done with an inverted cone bur, followed with a smooth fissure and all 
 walls should be parallel to each other. 
 
 In cases where there is danger of encroaching upon the pulp by using the above 
 method, the procedure may be reversed, the enamel and a small portion of the dentine 
 
PORCELAIN AND GOLD INLAYS 
 
 171 
 
 removed, as in Fig. 26. If tiiese methods do not seem to give sufficient anchorage, 
 or the tooth is broken well up on the lingual, the cavity should be extended sufficiently 
 on the lingual to gain the required retention, Fig. 27. 
 
 Fig. 25 
 
 Fig. 26 
 
 With the exception of very large, thick restorations, pins are contra-indicated as 
 they so weaken the porcelain that it is sure to fracture at this point. 
 
 In atrophied teeth the labial margins should be extended gingivally sufficiently 
 to reach the normal contour of the tooth, otherwise the inlay will be noticeable. 
 If this extension does not go beyond the incisal third the retention may be formed 
 the same as in fractures. If the defect is in the middle third of the tooth, it is 
 advisable to remove the entire labial surface on account of the objectionable changes 
 of the gingival third. First remove the enamel with carborundum stones, then shape 
 with inverted cone burs, extending it to the free margin of the gums and well to the 
 
 mesial and distal. Fig. 28 (mesial) Fig. 29 (distal). The porcelain should form the 
 contact point with the approximating teeth, otherwise there would be danger of 
 recurrence of decay. 
 
 THE MATRIX 
 
 Both platinum and gold foils have their advantage as a matrix material. While 
 gold can be used only for low fusing porcelains, it has the advantage of close adap- 
 tation to the margins of the cavity, thus makinga better fitting inlay with less burnish- 
 ing. It has the disadvantage of becoming very soft when subjected to the heat of 
 
172 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 the furnace, thus necessitating the careful investing of the matrix before baking. 
 For this reason platinum is becoming more popular daily. There are three thick- 
 nesses of platinum foil upon the market ordinarily, 1-1000, 1-1200 and 1-2000. The 
 thicker foils are more commonly used, the 1-1200 being preferable to the 1-1000. 
 This foil is slightly thinner and is sufficiently rigid to withstand the manipulating of 
 the porcelain without changing the shape. 
 
 It is not necessary to anneal platinum foil before using. .As a rule it is much 
 softer as it comes from the manufacturer than we can possibly make it without 
 subjecting it to high temperatures in the furnace. 
 
 GINGIVAL CAVITIES 
 
 If we have prepared our cavity afler the lines previously suggested it 
 will be found to be very difficult to force the matrix to the bottom of the cavity 
 without tearing. To facilitate matters it is an excellent plan to first shape an orange 
 wood stick to loosely fit the cavity, as shown in Fig. 30. Over this the platinum is 
 
 Fig. 30 
 
 Fig. 31 
 
 roughly formed. Fig. 31, care being taken to avoid large folds in the foil. If the stick 
 has not been too large I he foil will drop to the bottom of the cavit}' without a bit of 
 pressure having been brought to bear upon the thin foil. Next, place a pellet of 
 moist cotton in the bottom of the matrix thus formed and with one burnisher hold 
 the matrix to place again.st the Hoor of the cavity while wii;h the other carefully 
 burnish, starting at the center of the floor and gradually working towards the walls 
 of the cavity. At no time allow the burnisher to touch the platinum, always have an 
 intervening cushion of damp cotton. The matrix should he adapted to every portion 
 of the floor of the cavity before any attempt is made towards the walls or margins. 
 The final burnishing is done along the margins and on the surface of the tooth. 
 
 At first thought you would think the folds, formed in shaping the matrix over 
 the stick, would remain in the finished matrix; however, if it is carefully done every 
 one will disappear as the burnishing proceeds. 
 
 After the burnishing is completed the matrix should be packed full of camphor 
 gum (Dr. Allen) letting it extend slightly beyond the margins. This will tend to 
 remove any rocking that may be present. After teasing the matrix from the cavity, 
 the camphor may be burned away, leaving the matrix clean and in normal shape. 
 
PORCELAIN AND GOLD INLAYS 173 
 
 SIMPLE APPROXIMAL CAVITIES 
 
 The orange wood stick is equally of value in these, as it was in the gingival 
 
 cavities. In the first case the end of the stick was fitted to the cavity, while in this 
 
 the side is used, as in Fig. 32. The platinum is shaped over one side, the two edges 
 
 and the end of the stick, as in Fig. 33. On account of the approximating tooth it 
 
 Fig. 32 Fig. 33 Fig. 34 
 
 is necessary to bend the edges of the platinum forming a flange around the matrix. 
 In this manner the matrix readily goes to place even though there is but little sepa- 
 ration, Fig. 34. The matrix is then filled with damp cotton and burnished to place, 
 starting at the deepest part of the cavity and graduallj^ working towards the margins. 
 After this is accomplished any rocking of the matrix may be removed by stretching 
 damp English twill tape tightly over che matrix, or better still, u.=e a heavy rubber 
 
 Fig. 35 Fig. 36 Fig. 37 
 
 band, stretching this over the entire matrix and burnishing over this sufficiently to 
 bring the platinum finally against the tooth. 
 
 If it is necessary to trim the matrix that it may be removed easily, it should 
 be done before the final burnishing, then replaced and burnished, using the rubber 
 band. 
 
174 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 CAVITIES INVOLVING THE INCISAL EDGE 
 
 Ordinarily the most difficult matrix to form without tearing, is one for step 
 cavities But by carefully carrying out the following instructions it will be found 
 very simple and in the step where folds are so annoying there will not be a wrinkle. 
 
 In shaping the orange wood stick, one side, the end and one edge are used, as 
 in Fig. 35. Over this the platinum is shaped, as in Fig. 36, again bending the edge 
 of the platinum back in the form of a flange in order that it may pass freely between 
 the teeth. 
 
 Place in the cavity and pack with cotton and burnish carefully into the deep 
 portion of the cavity, being careful not to permit the platinum folding over on the 
 labial surface. It should stand perfectly parallel with the labial margin. With a 
 pair of cotton pliers gradually bend the matrix into the step, Fig. 37. With a flat 
 burnisher adapt closely to the labial wall and in the step, then with the same burnisher 
 
 Fig. 38 
 
 Fig. 39 
 
 Fig. 40 
 
 carry the surplus on the labial wall to place, Fig. 38. Next carry the approximal 
 portion of the step to place. Fig. 39, and finally fold back the portion covering the 
 gingival of the step. Fig. 40. This fold in the platinum stops at the cavo-surface 
 angle, consequently it does not interfere with the adaptation of the inlay. Burnish 
 over the lingual margin carefully and use the rubber band as in the preceding case. 
 
 EQUIPMENT 
 
 .Before taking up the manipulation of the porcelain, I wish to say a word in regard 
 to the nece-ssary equipment. 
 
 It will be noticed that very few burnishers were mentioned in the making of the 
 matrix. There are several sets, of from ten to fifteen instruments each, upon the 
 market. These are good, but an unnecessary expense to the man who does not 
 expect to make a specialty of porcelain, and even if he has this in mind, he has 
 di.scarded all but one or two before he reaches the point to be called a Specialist. 
 The writer .seldom uses anything but the S. S. W. amalgam burnishers Nos. 33 and 
 34. In these we have two sizes of ball burnishers, two flat burnishers, the edge of 
 which also works very nicely to draw the matrix into the angles of the cavity, and 
 the angle between the ball of the burnisher and the shank makes a very good sub- 
 stitute for the notched burnisher commonly used to burnish over the cavo-surface 
 
PORCELAIN AND GOLD INLAYS 
 
 175 
 
 angle of the cavity. Thus the two instruments are really equivalent to six. Besides 
 the two burnishers, the only instruments used were a pair of locking pliers and a pair 
 of small shears for trimming the matrix. 
 
 In buying a supply of porcelain it is well to procure the whole set of colors, even 
 though some of them are seldom used. 
 
 The selection of a furnace depends entirely upon the operator's surroundings. 
 If he is located where there is nothing but a night current of electricity, or no current 
 at all, he will have to get along with a gasoline furnace. While, if there is a day 
 current, he should not stop short of an electric furnace with a pyrometer attach- 
 ment. The time is coming when a man will be just as much out of place with a 
 furnace without a pyrometer as he would be with a vulcanizer without a ther- 
 mometer. 
 
 The proper baking of porcelain should not be underestimated. Many a good 
 inlay has been ruined because the dentist thought he could time his furnace or tell 
 by the glow of the muffle. 
 
 If you have no day current you can get very satisfactory results with the use of 
 a device designed by the writer after the suggestion of Dr. Woodbury, of Council 
 Blufifs, Iowa. Obtain a soapstone crayon from a book store or a dealer in metal 
 
 Fig. 41 
 
 worker's supplies. Take a piece two and one-half inches long and shape as in Fig. 
 41. At "A" it is simply made smaller to make a more convenient place to get a 
 hold with tongs in putting in and removing from the furnace. From "B" to "D" 
 it is hollowed out about 1-16 of an inch to prevent the gold dropping into the furnace. 
 " C " is a series of small depressions made with a large size cherry bur. These should 
 be as close together as possible without running into each other. "E" is a hole 
 extending almost through the block and is used for holding crowns while baking, and 
 also acts as a "center" for placing the inlay. As all gasoline muffles are hotter in 
 the rear than in the front there is a certain point, between "E" and "D," at which 
 the pure gold will melt, exactly the same time that a higher fusing porcelain reaches 
 a proper bake, when placed directly over "E," which is in a hotter portion of the 
 muffle. Pure gold should always be used and by a little experimenting one can 
 regulate his pyrometer by shifting the pellet of gold from one hole to another so that 
 he may get any kind of a bake he desires, from a biscuit to a high glaze. The inlay 
 should be placed at exactly the same spot each time and the slab placed in the 
 muffle exactly the same distance each time. A mica door should be used and the 
 slab and work should be removed just as soon as the gold is seen to melt. The same 
 device will work in electric furnaces, but not so well, as the heat is more uniform 
 throughout the muffle. 
 
 SELECTING THE COLORS 
 
 Many methods have been used in building up the colors for an inlay. A popular 
 method is to select at least three colors, one for the gingival third, one for the middle 
 third, and another for the incisal third. 
 
176 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Although we are dealing with a substance entirely different from the tooth 
 structure, I believe the best results can be obtained only by following Nature's 
 scheme. In this manner there is a gradual shading from the brownish yellow neck 
 to the blue tip. 
 
 We will first consider the anatomy of a tooth. From a practical standpoint 
 all dentine (unless artificially stained) is the same color, namely, a brownish yellow, 
 and all enamel is blue. If this one point is remembered by the beginner, three- 
 fourths of his trouble will be eliminated. It is so common to find a man trying to 
 use every color in the outfit, when in reality two or three colors properly applied will 
 meet almost every requiremant, except in discolored teeth. 
 
 A longitudinal section of a tooth will clearly show the relation of the enamel 
 and dentine, Figs. 42-43. It will be noticed that the enamel at the neck is thin and 
 the dentine predominates decidedly, while at the tip the enamel predominates. As 
 the dentine is of a brownish yellow color and there is very little blue enamel covering 
 it in the gingival third, naturally the tooth would have the color of the dentine, while 
 
 Fig. 42 Fig. 43 
 
 at the tip, where there is practically no dentine, it would take the color of the enamel, 
 and in the middle third, where the dentine and enamel are more nearly equal, we 
 find a composite of the two colors, or a greenish gray. 
 
 To prove that it is a difference in quantity of dentine and enamel, and the 
 relative proportions of each that gives us the various shades in teeth, rather than a 
 difference in coloring matter, examine a few of the patients who present themselves. 
 
 Patient A , we will say, has a decidedly yellow tooth. On examination we will 
 
 find the crowns are short and labio-lingually they are very thick. The dentine 
 
 extending to the cutting edge, Fig. 42. Patient B has a light blue tooth; here 
 
 we find a much thinner tooth labio-lingually. Fig. 43, the labial and lingual plates 
 of enamel come almost together in the middle third, consequently the tooth is 
 light and receives most of its color from the enamel. 
 
 In selecting the color of a tooth, get the shade of the dentine as near the gingival 
 as possible where the enamel is the thinnest, and select the enamel at the very tip, 
 where it is free from dentine. Always cover the shade guide with a finger, except 
 
PORCELAIN AND GOLD INLAYS 177 
 
 an amount in proportion to the tooth. As a matter of convenience, the series of 
 shades should be grouped together, ranging from light to dark. This makes the 
 selection much easier. The normal dentine colors, in the leading makes of porcelain, 
 ranging from light to dark, are as follows: 
 
 White's High Fusing: T, R, P, I, H, J, K. 
 
 Brewster's High Fusing: A, B, C, D, E, F, G, H. 
 
 Consolidated High Fusing: B, C, D. I, J, K, L, M. 
 
 Whiteley's Inlay Porcelain: 3, 4, 5, 6, 7, 8, 23, 24. 
 
 Brewster's Gold Matri.x: 1, 2, 3. 
 
 Jenkin's Porcelain Enamels: 22, 20, 17, 4, 7, 27, 12 
 
 Brewster's Low Fusing: 1, 2, 3, 4. 
 
 The colors of the enamels are: 
 
 White's High Fusing: E, C. 
 
 Brewster's High Fusing: T; occasionally U. 
 
 Consolidated High Fusing: S, T. 
 
 Whiteley's Inlay: 13. 
 
 Brewster's Gold Matrix: 10. 
 
 Jenkin's Porcelain Enamels: 5, 25. 
 
 Brewster's Low Fusing: 11. 
 
 There is no rule in the selection of colors for discolored teeth. The discoloration 
 is always in the dentine and may be a decided brown, or a dark blue, or a combination 
 of the two. 
 
 In selecting the color for the dentine we may find the color between two shades 
 upon the ring; if this is the case always select the tlarker shade — for example, if we 
 were using S. S. W. high fusing porcelain and find "I" a little light and "H" a little 
 dark, use "H." It is seldom necessary to use more than one shade for reproducing 
 enamel. 
 
 APPLYING COLORS 
 
 In the high fusing porcelains it is advisable to first use a porcelain of different 
 density, as the translucency of these porcelains is so great that if we should use the 
 sa-ne porcelain throughout, we would have considerable trouble from shadows 
 and cement, changing the color of an inlay. This porcelain, commonly known as 
 foundation body, should be slightly higher fusing and of different refracting proper- 
 ties. It is not necessary, as some think, that this should be of a different color. On 
 the other hand, better results can be obtained easier by using a foundation body of 
 a color more nearly resembling the dentine. 
 
 We will first consider the building of the colors for a gingival cavity. After 
 removing the matrix from the cavity, grasp it in a pair of pliers at some point where 
 there is an excess of platinum. 
 
 Take a small portion of the yellow foundation porcelain upon a glass slab and 
 mix with just enough water to make a doughy mass. There should be no excess of 
 moisture standing upon the surface. A good way of knowing when the mix is just 
 right is to pass the edge of the spatula through the mass; if the halves do not flow 
 back together or break in cutting, the proportions of water and porcelain are correct 
 Take a small amount of the porcelain upon the point of the spatula and place in the 
 bottom of the matrix, then with the gnarled portion of the handle, jar to place. An 
 excess of moisture, or too much jarring, will have a tendency to separate the particles 
 of porcelain, the heavier going to the bottom, leaving lighter on the surface, thus 
 
178 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 ruining the quality of the finished porcelain. Just as soon as an excess of moisture 
 appears upon the surface it should be removed either by bits of blotting paper or 
 by touching the damp porcelain to the dry powder, then removing any that may 
 stick with a dry camel's hair brush. This foundation porcelain should in no case 
 come to the margins of the cavity, but should be built only to within about a milli- 
 meter of the surface, as shown in Fig. 44. It is not necessary to use any scheme to 
 direct the shrinkage, such as cutting crosses in the porcelain, varnishing the matrix, 
 etc., as even if the matrix does change, we have an opportunity of reburnishing, 
 as we left all our margins free. This should be baked to a low glaze. 
 
 WKM 
 
 W^ 
 
 
 ^ 
 
 ^ 
 
 
 ^ 
 
 ■^ta 
 
 
 £0 
 
 , w| 
 
 w f 
 
 m 
 
 
 ^^mW^^^ 
 
 „,^ MCl$g^ 
 
 ?/ 
 
 
 M 
 
 
 ««d 
 
 
 — .^ 
 
 M 
 
 
 e- 
 
 m 
 
 1 ■■'5|^^ 
 
 II 
 
 44 
 
 H^^^^^^l 
 
 45 
 
 
 46 
 
 Fig. 44 
 
 Fig. 45 
 
 Fig. 46 
 
 After reburnishing, grasp the matrix in locking pliers and take a small quantity 
 of the porcelain selected to restore the dentine and carefully fill the crevices caused 
 by the shrinkage of the foundation body. Then add enough of the dentine porce- 
 lain to reproduce che dentine of the tooth. Great care should be taken in placing 
 this porcelain, as just the right amount of space should be left for the overlying 
 enamels. The dentine porcelain should be carried to the surface at the gingival, 
 receding gradually as the incisal is approached. Fig. 45. If the shrinkage is ex- 
 cessive a second bake may be necessary. This should also be baked to a low glaze, 
 and, in fact, every bake until the last, otherwise the porcelain would be overbaked 
 on the finish. Next, restore the enamel with the blue porcelain. Fig. 46, never 
 building it beyond the margins, as the amount of shrinkage is verj' uncertain. If the 
 shrinkage brings the surface below the proper contour, add sufficient to restore the 
 shrinkage. 
 
 Do not try to make inlays in a hurry. If a few extra bakes will give a better 
 result, do not try to do it all in one. 
 
 The same scheme of building colors, as illustrated for gingival cavities, is used 
 for simple approximal cavities. 
 
PORCELAIN AND GOLD INLAYS 
 
 179 
 
 In Fig. 46 you will notice the manner of building up the foundation porcelain. 
 As before, the margins are kept entirely free, thus preventing a change in the matrix 
 in this region and enabling the operator to reburnish if he feels in doubt of his adapta- 
 tion. Fig. 47 shows the restoration of the dentine. If the cavity is large and the 
 gingival margin extends to the neck of the tooth, this porcelain is built quite to the 
 surface, receding as it approaches the incisal margin. It will be noticed that both 
 the labial and the lingual surfaces are trimmed away about equally. This was done 
 simply for the pleasing effect if examined on the lingual. However, the writer often 
 thinks it prevents, to a large extent, the change in the inlay, from shadows. It 
 may be necessary to apply this dentine portion the second time to compensate for 
 the shrinkage. On this the enamel porcelain is built, bringing it just flush with the 
 margins. This will necessitate a second baking, but it is difficult to judge shrinkage 
 and it also gives one an opportunity of making a slight change in the colors if his first 
 selection was not correct. 
 
 Fig. 46 
 
 Fig. 47 
 
 In cavities of the third class, the foundation body is carried only to within about 
 a millimeter and one-half of the incisal edge. Fig. 48. The dentine porcelain may 
 stop about the same point or extend entirely to the cutting edge, depending entirely 
 upon the labio-lingual diameter of the tooth. As a rule we will find it necessary to 
 extend the dentine quite to the surface at the gingival, Fig. 49, as we select the dentine 
 where it is modified to a certain extent by the enamel and do not get the true dentine 
 color. 
 
 In all cases be particular to restore the contour of the dentine as it originally 
 was in the tooth. Fig. 50. The enamel is contoured exactly as you wish the finished 
 inlay and just flush with the margins. Never guess at an excess which will compen- 
 sate for the shrinkage, as there is no fi.xed rule regarding the amount of shrinkage 
 and the less we use a stone in finishing our inlay the better the result. 
 
 Before taking up the next step, it may be well to mention a few precautions, 
 helps, etc., in the working of the porcelain. Never lay the matrix down, but grasp 
 it in a pair of pliers and lay the pliers so that the inlay will stand out from the edge 
 of the table. 
 
 Distilled water is preferable to alcohol for mixing all porcelains, as it evaporates 
 more slowly allowing ample time for carving the porcelain. Do not try to work the 
 
180 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 porcelain too damp, as it is impossible to build contours, and the porcelain ingredients 
 have a tendency to separate, thus producing a weak product. 
 
 It is seldom necessary to mix colors. Get shades by laying one color over 
 another. Never attempt to build in the enamel color without having first baked 
 the dentine color to a low glaze, as the colors will blend and produce an entirely 
 different result. In removing an excess of moisture, the best absorbent is the dry 
 porcelain powder which is being used at the time. Touch the inlay to the dry powder, 
 then brush away the adhering particles with a soft dry camel's hair brush. Never 
 use a damp brush to remove the excess of porcelain on the margins of the matrix, 
 it simply makes a thinner layer of the porcelain and makes it difficult to remove. 
 A better way is to loosen the particles of the body with the point of the carving in- 
 
 Fig. 48 
 
 Fig. 49 
 
 Fig. 50 
 
 strument and brush away with a dry brush. Remember that low fusing porcelains 
 are more nearly opaque than the high fusing, consequently it is necessary to carry 
 the dentine color to the surface of the inlay. Otherwise the enamel color will cut 
 it out completely. 
 
 Before baking, always examine the under or cavity surface of the matrix to 
 make sure there has no porcelain run over on that side. If there has, it should be 
 removed before placing in the furnace, as it will be impossible to remove the matrix 
 and will prevent the inlay going to place. Be sure the porcelain is entirely dry 
 before placing in the hot furnace. Do not bake too rapidly. A much higher grade 
 of porcelain will be produced by starting with a cool furnace and gradually raising 
 the temperature, using plenty of time to allow the heat to penetrate the body. 
 Placing in a hot furnace or raising the temperature too rapidly will cause a crust to 
 form on the surface and the inner part will be porous. 
 
 Do not apply the body in the center of the inlay and expect it to flow to the 
 margins by jarring. It may seem to do this, but at the final bake a row of bubbles 
 will appear along the margins as a result of this. It is better to build all over the 
 surface to a slight excess, then trim down to the desired contour. 
 
PORCELAIN AND GOLD INLAYS 
 
 181 
 
 REMOVING THE MATRIX 
 
 After the inlay has been properly baked, the next step is to remove the matrix. 
 This should be carefully done by grasping the free edge of the platinum in a pair of 
 pliers and peeling toward the center. This may be more easily accomplished bj' 
 first dipping the inlay in water. 
 
 After removing the matrix the cavity surface of the inlay must be roughened 
 to permit the cement to properly adhere. This may best be accomplished by 
 imbedding the inlay in wax, leaving only the cavity surface exposed and etch with 
 hydrofluoric acid. It should be left in the acid from two to five minutes, depending 
 upon the porcelain and the strength of the acid. This is very important and should 
 not be neglected. A simple gingival inlay with four antagonizing walls will not hold 
 if it is not properly roughened. 
 
 The acid should be thoroughly removed by washing, using a fine, stiff" brush. 
 
 Figs. 51-52 
 
 SETTING THE INLAY 
 
 The so-called "Cement Problem" has confronted the porcelain worker for years. 
 A great deal of the change in color, on cementing an inlay to place, is due to a too 
 thick layer of cement between the inlay and the cavity. This may be due to lack of 
 adaptation of the inlay, using cement so thick that the inlay fails to go to place, 
 or having a cement that is so coarsely ground that it will not permit the inlaj' going 
 to place. The color of the cement has little to do with it, a light cement being nearly 
 as bad as a dark under similar circumstances. Thin layers of cement will transmit 
 light; therefore, if we expect our inlays to retain their color after setting, we must 
 have our adaptation so perfect that the layer of cement will be thin enough to trans- 
 mit light. 
 
 No cement should be used except one which is especially ground for inlay pur- 
 poses. The writer prefers a cement pearl gray in color. This should be carefully 
 mixed to a creamy consistency, being careful that there is sufficient powder to take 
 up all the free acid. This should be spread over the dry cavity with an explorer, 
 using as nearly as possible the exact amount necessary. Force the inlay to place 
 and keep under pressure until the cement sets. If the work has been properly done 
 there should be little or no grinding to do after the inlay sets. 
 
182 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 GOLD INLAYS 
 
 Probably nothing ever introduced into dentistry was so universally taken up 
 and created such wild enthusiasm as did the gold inlay, when Dr. Taggart introduced 
 the casting process. There was scarcely a practitioner, no matter from how remote 
 a corner of the land he came, who had not adopted the process within the year. 
 And today, alas, how expensive this wild rush has been to many a man's practice. 
 Undoubtedly greater care is needed in making a gold inlay than ever was called for 
 in porcelain restorations. The difficulty in thoroughly roughening the gold to insure 
 perfect adhesion of the cement, necessitates a careful consideration of mechanical 
 retention in the cavity. 
 
 Although the casting process has decided advantages in most cases, there are 
 certain cases when the old method of burnishing a matrix is preferable. While in 
 others a combination of the two will produce the best results. 
 
 In small cavities with four walls, much time can be saved and an equally good 
 inlay made by burnishing a matrix of platinum and filling with pure gold. In cases 
 of large size where it is difficult to remove the wax without impairing the margins, a 
 combination of a pure gold matrix and the remainder cast, is indicated. 
 
 Figs. 53-54-.55 
 
 STUDY THE OCCLUSION 
 
 Before starting the preparation of a cavity for a gold inlay a careful consideration 
 of the occlusion must be made. A cavity must have a resistance form to antagonize 
 all stress upon the inlay or it will surely be dislodged. Have the patient move the 
 jaws laterally and notice the stress in this direction, then mesio-distally, as well as at 
 rest. Many peculiar conditions are brought out by doing this, which may completely 
 change the nature of the cavity preparation. 
 
 CAVITY PREPARATION 
 
 Simple Approximal Cavities 
 The general outline of a cavity for a gold inlay for simple cavities is very similar 
 to that given for porcelain. In cases where the occlusion is normal, the lingual wall 
 should be cut away to permit the removal of the wax pattern or matrix, in that 
 direction. The incisal and gingival walls should be parallel to each other mesio- 
 distally and there should be a decided seat under the labial wall. The incisal and 
 gingival walls should diverge slightly from labial to lingual, to permit the removal 
 of the pattern. 
 
PORCELAIN AND GOLD I NLA YS 
 
 183 
 
 The technic of the operation consists of, first, breaking down an>' thin enamel 
 margins and cutting away the Ungual wall with chisels, always remembering that 
 unless enamel has an underlying support of dentine, it is worthless and should be 
 removed. Next, with a smooth square-end fissure bur in a right angle, entering 
 from the lingual, extend the gingival margin sufificiently to permit the removal of the 
 pattern. Form the incisal wall in the same manner, and with the square end of the 
 bur cut the seat under the labial wall. Then, with hatchet and hoe excavators 
 make a definite angle at the junction of the incisal, gingival and labial walls with the 
 axial. In very deep cavities it is well to build in with cement, care being taken not 
 to carry it to an extreme. All margins should be smooth and slightly beveled. 
 
 CAVITIES INVOLVING THE INCISAL ANGLE 
 
 In this class of cavities it is preferable to use a step for incisal retention. In 
 cutting this, fine grit carborundum stones are used, extending it sufficiently laterally 
 to permit making a pit in perfectly sound dentine. On the labial, only sufficient 
 should be cut away to give the enamel a protection of gold. Much less cutting is 
 necessary as compared with that for a gold filling. 
 
 57 
 
 
 Figs. .56-57-58 
 
 The lingual wall of the step should be cut away to permit good anchorage in 
 dentine. At the end of the step should be a well defined pit. 
 
 The body of the cavity is prepared much the same as that for porcelain, cutting 
 away the lingual to permit the easy removal of the pattern. The gingival wall 
 should be flat and there should be a flat seat under the labial plate. In deep cavities 
 the axial wall may be built out with cement, care being taken that all margins are 
 freed from cement before the impression is taken. 
 
 CAVITIES IN BICUSPIDS AND MOLARS 
 
 The ideal place for gold inlays is in the bicuspids and molars. They eliminate 
 the great difficulty of placing cohesive gold in inaccessible cavities and have greater 
 strength. Within a very short time the inlay will almost take the place of the gold 
 crown. The misfitting band and inflamed gum will be a thing of the past. 
 
 In all proximal cavities in bicuspids and molars there should be a step including 
 all fissures on the occlusal surface. 
 
 Figs. 56, 57 and 58 represent a cavity in the bicuspid. In the proximal portion 
 there should be a flat gingival seat, the buccal and lingual walls should be as near 
 parallel to each other as possible and permit the removal of the impression. The 
 
184 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 occlusal portion should be of sufficient width and depth to give strength to the inlay 
 and should terminate in a definite dove-tail which affords retention from dislodgment 
 approximall}'. In badly decayed teeth, the cavity should be built out with cement, 
 to within a millimeter and a half of the surface. This will give sufficient bulk of gold 
 and will make the inlay of better retention form. 
 
 In larger cases, especially where both mesial and distal surfaces are involved, 
 and the buccal and lingual walls are weak, the cusps should be removed and the tip 
 restored with gold. 
 
 Molar cavities, Fig. 59, are prepared along the same lines, making an occlusal 
 step extending into all the deeper fissures. The pulpal and gingival walls should be 
 flat and at right angles to stress. The buccal and lingual walls should be as near 
 parallel to each other as possible and permit the removal of the pattern. 
 
 All the above cavities are for the restoration of lost tooth structure, and are not 
 intended to carry lost teeth in bridge work. The cavities following are intended more 
 especially for use in bridge work and the retention of teeth. 
 
 Fig. 59 
 
 GOLD INLAYS FOR BRIDGE ABUTMENTS 
 
 The casting process opens a field in bridge work of inestimable value. In the 
 past many teeth have been mutilated for the construction of bridge work, which in 
 the future will be saved almost in their entirety with the use of inlays. We have all 
 experienced the difficulty of properly shaping molars and bicuspids to permit a close 
 fitting shell crown. While in the anterior teeth it necessitated the use of a shell 
 crown or the entire destruction of the crown of the tooth for a Richmond crown to 
 permit of bridge work. With inlays a much more sanitary and an equally strong 
 anchorage may be made. It is a system, however, that will necessitate the greatest 
 care on the part of the operator in regard to every detail in the preparation of the 
 cavity adaption of the inlay and attachment of the dummies. 
 
 In preparing a cavity for an abutment we should examine the occlusion minutely 
 and make a careful estimate of the stress that will be brought to bear upon the 
 restoration. Always bear in mind that there is a certain amount of movement of 
 teeth in their sockets and that the movement may not be equal at both ends of the 
 bridge; hence unless we have an absolute mechanical anchorage the inlay will surely 
 be dislodged. 
 
 We will first consider the preparation of a cavity in a cuspid. In most cases it 
 is advisable to devitalize and use an iridio-platinum pin as anchorage. After having 
 
PORCELAIN AND GOLD INLAYS 185 
 
 removed the pulp and filled the canals, take a carborundum stone and remove the 
 approximo-lingual angle. Then with inverted cone burs extend the proximal 
 portion well to the gingival, Figs. 60-61-62, making a flat gingival seat. The ap- 
 proximal portion of the cavity should be extended labially sufficiently to make the 
 labial margin perfectly self-cleansing and at the same time not so far as to show the 
 gold appreciably. The pulpal wall of the main portion of the cavity should be 
 
 Figs. 60-61-62 
 
 made flat and at right angles to the long axis of the tooth. The incisal edge should 
 be cut away sufficiently to permit its restoration with gold. In no case should the 
 labial plate be left standing without this protection. All margins should be at right 
 angles to the surface of the tooth with a slight bevel of the outer third of the enamel. 
 The root canal should be enlarged to admit a 16-gauge iridio-platinum bar and be a 
 depth equal at least the length of the crown of the tooth. 
 
 Figs. 63-64-65 
 
 In cases for small bridges a staple inlay may be used without the necessity of 
 devitalizing, as Figs. 63, 64, 65. The lingual plate of enamel is removed with car- 
 borundum stones entirely to the incisal. Each approximal surface is prepared 
 similar to that described above. Then with inverted cone burs make the lingual 
 wall flat and at right angles to the surface. At the junction of the middle and incisal 
 thirds a step is formed with an inverted cone bur. The cavity should be extended 
 to, and include, the incisal edge, which should be restored with gold. 
 
186 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Figs. 66-67-68 
 
 Figs. 66, 67 and 68 represent a lateral incisor with an approximal preparation 
 for bridge anchorage. In this case the cavity is stepped on the incisal and an 18- 
 gauge iridio-platinum pin extends into the canal from the step. In all cases the 
 important points are, first, extend the cavity to self-cleansing areas; second, obtain a 
 thorough resistance form, and third, procure positive anchorage from all stress. 
 
 Figs. 69-70-71 
 
 In bicuspids and molars there should be post anchorage in badly broken down 
 cases. Where the greater part of the tooth is intact, the cavities should include 
 both mesial and distal surfaces extending well to the gingival on both approximal 
 surfaces. Fig. 69. 
 
 Figs. 70 and 71 show a badly broken down molar with the pulp chamber built 
 out with cement. In these cases it is important to have flat gingival seats with 
 sufficient breadth to withstand stress. All the cusps should be ground away suf- 
 ficiently to protect them with gold. 
 
 FORMING THE MATRIX OR PATTERN 
 
 In small approximal, pit, gingival and occlusal cavities, it is much easier and 
 quicker many times to use the old method of forming a platinum matrix and filling 
 with pure gold, rather than the new method of casting. 
 
PORCELAIN AND GOLD INLAYS 187 
 
 Wc will take for example a gingival cavity. Here we have the secretions of 
 the mouth to annoy us, as well as the close proximity of the gum margin. The wax 
 has a tendency to crumble under moisture and again it is difficult to remove the wax 
 when the cavity extends beneath the gum. In simple approximal and small occlusal 
 cavities it is a comparatively simple matter to burnish a matrix, within a very few 
 minutes it may be filled with gold and ready for cementing to place and finish. 
 
 The method preferred would be to form an orange wood stick to loosely fit the 
 cavity, over this shape a piece of 1-1000 platinum foil as described for a porcelain 
 inlay, (Figs. 30-31). Remove the matrix and place in the cavity and burnish to 
 place, being careful to spread over the floor of the cavity first, then gradually over 
 the walls and margins. The excess may be trimmed almost entirely away along 
 the gingival margins if the gum interferes. Remove from the cavity, heat in a 
 flame until all carbon has been burned off, cool and coat the surface next to the 
 cavity with a thin solution of chalk in alcohol. Great care should be used in ap- 
 plying the chalk, not to permit any to run into the matrix, as it will cause no end of 
 trouble in melting the pure gold. Allow the alcohol to evaporate, then place 
 the matrix upon a soldering block and fill about one-half with pure gold. Do not 
 use flux, as it is unnecessary' and causes pits in the inlay. Immediately drop 
 the matrix into nitric acid which will remove the chalk. Place in the cavity and 
 reburnish. Unless the inlay is large the second time the gold may extend to the 
 surface. After cleaning in nitric acid, roughen the surface with a small bur and 
 cement to place. Before the cement starts to cr^'stalize, burnish all margins care- 
 fully. Then finish the same as a filling. If there are small tears in the bottom of 
 the matrix there will be no danger of the gold flowing through, if the cavity surface 
 is carefully coated with the chalk. 
 
 In large contour cases the preferable method is to use the casting process. 
 When this method was introduced, it seemed so easy and simple that the majority 
 of men rushed at it with little thought of what the probable outcome would be. There 
 is no operation in dentistry more difficult than properly removing and investing a 
 wax pattern. This may seem a strange statement but it is true, nevertheless. In the 
 first place the cavity should be so prepared with parallel walls that there is a certain 
 amount of frictional retention and if this is done there is considerable danger of dis- 
 torting the pattern in removing. 
 
 When it comes to investing the pattern there is great danger of changing its 
 shape. 
 
 THE WAX PATTERN 
 
 In considering this step in inlay construction, it is important that we first con- 
 sider the material we are to work with. There has been almost as many makes of 
 wax thrust upon the profession as there have been casting machines, and the majority 
 are absolutely worthless. The fact of the matter is, our best base plate waxes are 
 far superior to the majority of inlay wax offered for sale. 
 
 The important feature in an inlay wax is to have one with the least possible 
 amount of inorganic material present. In other words, one that can be completely 
 destroyed by moderate heat. The next essentials are, tenacity, close grain and 
 rigidity when cool. The ideal wax should be one that could be softened and formed 
 in a cone with dry heat and when soft should work like chewing gum. When forced 
 into the cavity it should not crack or crumble, but mold to any form desired, either 
 with the use of the fingers or instruments. After chilling, it should carve easily and 
 take on a high polish. 
 
188 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 When making the wax pattern, the tooth should be slightly moist to prevent 
 the wax sticking. Warm the wax until it is like putty, shape in the form of a cone 
 and force into the cavity with the thumb and finger, compressing the wax as much as 
 possible with the fingers to insure perfect adaptation to the walls of the cavity. In 
 approximal cavities an excellent plan is to use a heavy piece of dam, placing it between 
 the teeth, first allowing it to rest against the approximating tooth until the wax is 
 forced into the cavity, then with considerable tension upon the rubber, force the 
 wax to place in the cavity. With flat burnisher, working from the center of the 
 cavity towards the margins, work down smooth and at the same time remove the 
 excess. The wax should be as nearly as possible the exact contour desired in the 
 finished inlay, having no more of an excess over the margins than the thickness of 
 paper. After getting as smooth as possible with the burnisher, polish with a pellet 
 of cotton or a soft tape passed between the teeth. 
 
 Great care should be used in the removal of the pattern. It is best not to 
 attempt the insertion of the sprue until the pattern has been removed, as many 
 times it would be impossible to attach at the most advantageous point. With gentle 
 pressure upon the labial and lingual surface, using a small pellet of cotton in the 
 cotton pliers, loosen the pattern. The greatest care should be used in its handling 
 
 Fig. 72 
 
 after it has been dislodged, as the margins are thin and easily bent out of place. A 
 very convenient receptacle to allow the pattern to drop onto, from the cavity, is a 
 large size mouth mirror frame, one that has the glass broken away and replaced with 
 a thin layer of cotton. As soon as removed, the sprue should be attached and the 
 pattern covered with a thin layer of investment and should never be permitted to 
 lie around, even in water, for some future time to invest. 
 
 In bicuspids and molars after forcing the wax to place in the cavity, have the 
 patient close his teeth and move the jaws laterally, in order that the occlusal surface 
 may be as nearly perfect as possible. After trimming down the approximal portion 
 and smoothing as much as possible, have the patient close again to make sure the wax 
 has not been misplaced in the smoothing process. 
 
 A careful examination of normally occluding teeth will show the fissures and 
 sulci of the tooth extend deeper than the tip of the occluding tooth. So we should 
 carve the fissures slightly deeper than the impression made by the occluding tooth. 
 A very good tool for this purpose is a small pointed lancet, or in many cases the 
 ordinary hook scaler is excellent. After shaping the occlusal surface the occlusion 
 should be again tested to make sure the wax was not misplaced in carving. 
 
PORCELAIN AND GOLD INLAYS 
 
 189 
 
 At this point it might be well to mention the use of iridio-platinum pins as 
 anchorage. In many cases it is not only difificult to get the wax into the pits but it is 
 uncertain about their casting and lack of strength when cast, so a much better 
 method is the use of pins. An iridio-platinum wire, about 20 gauge, is preferable 
 for incisal anchorage, and 16 gauge for anchoring single inlaw's in root canals. If the 
 inlay is to be used for bridge retention, 14 gauge sprue wire should be used. In getting 
 
 Fig. 73 
 
 the pattern for an inlay where 20 gauge wire is to be used for incisal retention, it is 
 best to force the wax home in the cavity first, then heat the pin slightly and push it 
 through the wax into the pit. 
 
 In using pins in the canals, it is better to shape the wax in a cone around the 
 pin before inserting into the cavity, having first shaped and bent the pin to conform 
 to the cavity and canal. 
 
 In an inlay to be used as an abutment for a bridge, a square 14 or 16 gauge 
 iridio-platinum pin should be used. The pin should extend into the canal at least 
 
 Fig. 74 
 
 the length of the crown of the tooth, and should be bent at right angles and extend 
 beyond the contour of the tooth sufficiently to insure thorough union with the 
 dummies of the bridge. 
 
 The writer does not believe a soldered union direct with an inlay is good practice. 
 In the first place our solders lack strength and consequently in order to get sufficient 
 strength it is necessary to use such a large quantity of solder that we have destroyed 
 our self-cleansing margins. By using the heavy iridio-platinum union, all margins 
 can be made self-cleansing without weakening the bridge. If we are using a vital 
 
190 PRACTICAL MANUAL OF DENTAL CASTING 
 
 tooth as an abutment, it is a question in the writer's mind if it is good practice to 
 attach the inlay direct to the bridge, unless the extension is very large. A simple 
 approximo-occlusal cavity in a bicuspid should never be used in this way. If the 
 cavity is a mesio-occluso-distal, it may prove satisfactory, but the inlay should always 
 be constructed with the use of an iridio-platinum wire, as shown in Fig. 75. 
 
 If a simple approximo-occlusal inlay is used for anchorage it is not well to make 
 a solid union to the bridge, but instead, the iridio-platinum bar should rest within a 
 tube and set in the inlay. This is easily formed by shaping a piece of platinum plate over 
 the wire to be used, and this set in the wax in the region of the contact point. This 
 method allows a certain amount of movement which is always present during mastica- 
 tion, and prevents dislodgment of the inlay. 
 
 Fig. 75 
 
 In attaching the sprue, care should be taken to attach at such a point that the 
 gold will be forced as near as possible towards all margins of the inlay. If this pre- 
 caution is taken the defects, if any, will not be at the margins but some place upon 
 the surface of the inlay where it can be more easily repaired. 
 
 INVESTMENTS AND INVESTING 
 
 This particular phase of inlay work does not receive the attention it should. 
 In the first place the wax pattern should be so carefully made and polished over the 
 surface that it is without a flaw, then secondly, it should be invested with an invest- 
 ing material that will conform to the pattern and produce a casting as perfect as the 
 original pattern. Our neglect lies in using a too coarse investment and the careless 
 manner of applying it. 
 
 It is preferable to use a fine investment first, one which is easily painted over the 
 surface of the pattern and later invest in the cup with a coarser, more substantial 
 material. An excellent preparation for first coating the pattern is equal parts 
 powdered rouge and plaster, while there seems to be nothing better than equal parts 
 of extra fine powdered silex and plaster for the outer investment. If these invest- 
 ments are prepared by the dentist, he should be careful about thoroughly mixing the 
 ingredients, otherwise the investment will crack and shrink. It should be passed 
 through a fine sieve at least five times. 
 
 After removing the wax pattern from the cavity and attaching the sprue wire, 
 examine very carefully, and if there is any collection of saliva or blood, the pattern 
 should be thoroughly cleaned, first, in a stream of water from a water syringe, then 
 
PORCELAIN AND GOLD INLAYS 191 
 
 wiped carefully with a brush or pledget of cotton, moistened in alcohol. Attach the 
 sprue wire to crucible former and we are ready to invest. 
 
 Mix a small teaspoonful of the red investment with water until it is the con- 
 sistency of thick cream, then with a small camel's hair brush paint the surface of the 
 pattern carefully, making the first application very thin and be particular about work- 
 ing it into every minute angle. Gradually build up with this investment until there 
 is a thickness of at least 1-8 inch over the entire pattern. This investment should 
 extend down over the sprue wire and crucible former, otherwise there might be a 
 slight crack between the fine and the coarse investments, which would fill with 
 gold and possibly destroy the value of the inlay. 
 
 After the fine investment has set, nearly fill the cup, if you are using that style of 
 receptacle, with the coarser investment and invest the pattern and sprue and with 
 gentle jarring settle to place. If a ring is being used, set it over the inlay and fill 
 with the investment, being careful to work into every minute crevice and irregularity 
 of the first investment. 
 
 After the investment has set, the ring should be placed over a slow fire to dry. 
 It is preferable to have the investment heat slowly, as there is less danger of a change. 
 The heat should be gradually increased until the investment is a dull red to the 
 center, when it is ready for casting. 
 
 PREPARATION OF GOLD 
 
 It is very important to have our gold for casting free from all foreign matter 
 before placing it in the crucible to be cast. If we have been particular with the 
 treatment of the wax pattern previous to this time and it is a perfect counterpart 
 of our cavity, very little burnishing of the margins is necessary. Consequently it 
 is possible to use our scrap plate rather than pure gold. If we have been reasonably 
 careful with our scrap, kept it free from platinum or silver, the color is not bad for 
 fillings and it has the advantage of retaining its shape better than pure gold. 
 
 If scrap is used, it should first be boiled in 50% nitric acid to remove any base 
 metals that may be present, wash and place upon a charcoal block and melt. While 
 the mass is in a molten condition it should be sprinkled with Ammonium Chloride 
 (Sal Ammoniac). This should be repeated untilthe gold ripples like water. This 
 may be remelted in a carbon crucible and cast into ingots for use or used as it is. 
 
 If we are melting our gold in a crucible formed in the investment very little 
 flux, if any, should be used, as there is danger of its closing the opening into the 
 mold, thus preventing a perfect cast, if the gold goes down at all. 
 
 The importance of having our gold in perfect condition for casting must not be 
 overlooked. 
 
 It is hardly necessary to mention machines for casting, as there are so many 
 and all will get results if properly handled. Some require a little more care than 
 others, but good inlays may be had in any, from a tin can lined with wet asbestos 
 to the most complicated machines. I think, however, the centrifugal principle 
 among inexperienced college students, will give the most uniform results. 
 
 After the inlay is cast it should be washed thoroughly to remove all invesc- 
 ment attached, then placed in Hydrofluoric Acid, which will remove any fused silex. 
 The sprue should then be carefully cut off and the cavity surface examined minutely 
 for any small bubbles of gold that may be attached. If the red investment was 
 painted on very thin at first there will bo little troul)!e in lliis respect. 
 
192 PRACTICAL MANUAL OF DENTAL CASTING 
 
 If there is any difficulty in getting the inlay seated in the cavity, an excellent 
 method is to heat the inlay slightly and apply a very slight layer of mercury to the 
 surface; this will unite with the gold and, upon evaporating away with increased 
 heat, the gold will be left with a frosted surface. If the inlay is now placed in the 
 cavity any point that may rub against the walls will become burnished and can be 
 cut away. When the inlay goes to place perfectly, the surface should again be 
 etched for the better adhesion of the cement. 
 
 All inaccessible surfaces of the inlay should be trimmed and polished before 
 setting. However, if it is possible to reach the margin with a burnisher, it should be 
 left slightly flush to permit a thorough burnishing before the cement sets, after which 
 the margins should be finished and polished the same as for a gold filling. 
 
 AMALGAM BASE FOR GOLD INLAYS 
 
 By Steele F. Gilmore, D.D.S., Indianapolis, Ind. 
 
 In deep lying approximal cavities that are inaccessible (such as are distal cavities 
 in molars and bicuspids) rendering the adaptation of the wax model and its gold 
 replica to the cervical border uncertain, resulting in secondary or recurrent decay at 
 this point, this method is indicated. 
 
 Technic: After the preliminary opening of the cavity in a gross way, apply 
 the Ivory band matrix, and with it in place excavate the cavity floor with right angle 
 burs. The matrix acting as a guide to your instruments prevents them from slipping 
 into the soft parts, causing unnecessary pain and irreparable damage to the delicate 
 tissues occupying the interdental space. If you are satisfied with the preparation 
 of the cavity floor, together with its buccal and lingual walls, remove the matrix and 
 carefully stone the margins. Now if the approximal surface of the neck of the tooth 
 is irregular (concave, for instance) you can, with pliers, so swage and manipulate this 
 soft steel as to adapt it accurately to the surface above mentioned. Properly mixed 
 amalgam, in very small pellets, may now be vigorously burnished in and built up as 
 far as your judgment may dictate. Insert temporary stopping until the next sitting, 
 when complete preparation of the occlusal surface can be made. Or a quick setting 
 amalgam may be used and the model obtained at the first sitting. 
 
 Advantage: A perfect adaptation, without any of the elements of guess work 
 in this dark corner. The surface alignment of your filling is automatically provided 
 for at the cervical margin. To the delight of the patient, approximal ti'immers and 
 burnishers are not needed. You have re-inforced the weak point of all inlays. 
 There can be no electrical disturbance, since the two metals are insulated by the 
 intervening cement. 
 
SOME PLACES WHERE THE CASTING PROCESS HAS BEEN 
 FOUND USEFUL 
 
 By E. T. Tinker, D.D.S., Minneapolis, Minn. 
 
 In the following article it will be my endeavor to give 3011 a lew appliealions 
 of the casting process. 
 
 The first of which will be a method of casting a coping for a Richmond or 
 Porcelain crown, where it is necessary to reproduce the entire enamel margin, as in 
 cases of split roots, roots that have been supporting crowns and through improper 
 preparation are causing gingivitis, as well as many other cases that may come under 
 our care. 
 
 CASTING A COPING FOR RICHMOND OR PORCELAIN CROWN 
 
 In brief, the procedure is as follows: 
 
 Before removing all the enamel and beveling the root, take the measure and make 
 band of 22k. -30g. gold plate, contouring and roughly fitting same (Fig. 1). Prepare 
 the root as in Fig. 2; place the band in position and force softened casting wax to 
 place (Fig. 3). The band being slightly larger than the root acts as a matrix, forcing 
 
 1 
 
 S 
 
 Figs. 1, 2, 3, 4 and 5 
 
 the wax in direct contact; the free margin of the gum determines the depth to which 
 it shall go. Trim away all surplus wax, warm an iridio-platinum pin and force 
 through wax into the canal, attach the sprue and remove band, wax and post intact, 
 mounting same on crucible former (Fig. 4) and cast. By the aid of stones and disks, 
 dress down and polish, leaving a finished co];ing (Fig. 5), which is very strong and 
 one to which the gums take kindly. 
 
 I was very much interested in reading Doctor Kabeli's article in the May 
 number of Items of Interest, from the fact that it brought out the same difficulty 
 which some of my friends as well as myself have been ha\ing with the shrinkage of 
 gold when cast. 
 
194 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 TIN FOIL TO CONTROL SHRINKAGE IN CASTING 
 
 Through the courtesy of Doctor H. A. Knight, I will give you his method of 
 using tin foil to control the shrinkage in casting boxes for porcelain bicuspids and 
 molars when used as dummies for bridge work. Take a common pin tooth, molar or 
 bicuspid, cut off the pins and grind it as shown in Figs. 6 and 7; Fig. 6 showing it 
 from the occlusal and Fig. 7 from the gingival point of view. Take a sheet of casting 
 wax and adapt some very thin tin foil over one side of it. Warm the wax and press 
 to place, having the tin foil next to the ground surface of the tooth and carve as you 
 wish the finished piece. Attach the sprue in some convenient place, chill and using 
 
 8 
 
 Figs. 6, 7, 8 and 9 
 
 sprue as a handle, remove wax and foil from the tooth, chill again and with a pair of 
 small pliers grasp the foil by some small projection and separate from the wax (Fig. 
 8), being careful not to distort wax form, invest and cast. The space gained by the 
 foil will just about compensate for the shrinkage of the gold, the tooth slipping to 
 place without further grinding (Fig. 9). 
 
 Figs. 10. 11 and 12 
 
 GINGIVAL MARGIN RESTORATION 
 
 Another place where difficulty is often encountered is at the gingival margins 
 in large M. O. D. inlays. Doctor F. B. Kremer, of this city, suggested that in cases 
 where we have an otherwise perfect inlay, that we grind away a part of the defective 
 margin (Fig. 10), placing a little inlay wax and forcing inlay home over it (Fig. 11). 
 Remove inlay and wax intact, casting anew, which gives a very good result (Fig. 12). 
 This idea has been carried out in a good many different ways, for instance where a 
 
WHERE THE CASTING PROCESS HAS BEEN FOUND USEFUL 195 
 
 margin of a cavity containing an otherwise good inlay has become fractured, or 
 where a root has become affected by caries under a well made Richmond, the de- 
 fective parts of tooth can be prepared, wax placed over them and the old work 
 pressed to place, removed intact and cast, producing practically a new piece of work. 
 Numerous other conditions will present themselves to which this idea can be applied 
 advantageously. 
 
 CAST C;OLD CROWN 
 
 For contact, contour, occlusion and perfect relation to the root and gums, the 
 gold crown made by the following method comes as near the ideal for posterior teeth 
 as anything I have as yet found. Prepare the root along the accepted lines, construct 
 a gold band of 22k. -30g. plate and accurately adjust to the root and gingival, paying 
 no attention to contour as that will be taken care of later. Obtain a bite of occluding 
 teeth in wax and an impression of band and teeth mesially and distally in plaster. 
 Remove band and place it in impression. Make models and mount on an anatomical 
 articulator, oil all plaster adjacent to band, place warm casting wax in band and close 
 the articulator, giving it a lateral motion as in mastication, so as to produce a correct 
 occlusion, and carve. With a camel's hair brush paint melted wax on exterior of 
 band and carve contact points and contour. Remove from model, invest and cast 
 and when finished it will be found as near anatomically correct as any which have so 
 far been made, and its one great advantage lies in the fact that by not contouring 
 the band, we do not take the risk of disturbing its relation to the root, the perfection 
 of which we are all aware is the cardinal point in the construction of any crown, the 
 health of the surrounding tissues and the life of the operation depending almost 
 wholly upon it. 
 
CAST GOLD SPLINTS FOR PYORRHEA 
 
 By Dr. J. G. Lane, Philadelphia, Pa. 
 
 Showing more particularly a method of uniting the two plates of the splint 
 and the technique of making up the uniting medium. 
 
 Fig. 1. Finished splint in position. The two plates fastened tosrethcr by means 
 or iridio-platinum screws. 
 
 J /' 
 
 ^^^ 
 
 J. G. LANE, D. D. S. 
 OM 830 PERRY BUILDING 
 
 PHILADELPHIA 
 
 Fig. 2. Pattern for one plate of splint, showing graphite rods in position to 
 core the hole for the screws. In order to get the proper lineup for the cores they are 
 placed in wax pattern before the latter is removed from the model. 
 
 Fig. 3. Iridio-platinum blank for screw. Surplus material for head obtained 
 by partly fusing the end of the wire. 
 
 Fig. 4. Heading tool. Made by drilling a hole in a piece of steel and councer- 
 boring the hole to any sufficient depth with a round bur. This must be tempered. 
 
 Fig. r>. Sketch showing section of Heading Tool. (Xotc shape and depth of 
 counter-bore.) 
 
 Fig. (). Screw blank after same has been placed in the Heading Tool and the 
 surplus for head hammered down in counter-bore. 
 
 Fig. 7. Finished screw. Shank threaded, surplus material on head removed 
 with a file and slot cut with ribbon saw. 
 
CAMPBELL'S COW-BELL METHOD OF CASTING PLATES 
 
 By Dayton Dunbar Campbell, Kansas City, Mo. 
 
 In describing this simple and unique method of casting aluminum plates, we will 
 not go into the question of the superiority of the cast metal denture over one made 
 of x'ulcanitc, but give in a homely way the procedure in detail: 
 
 INVESTMENT MATERIAL 
 
 After taking your impression, coat it with your favorite separating fluid and 
 when dry rub well with soapstone and pour with an investment compound after the 
 formula originated by Dr. C. C. Allen, which consists of equal parts of Portland 
 cement and dental plaster. This compound is in keeping with the simplicity of the 
 casting machine, and in fact, is cheaper than plaster, sets very fast and is free from 
 shrinkage and expansion, making an ideal compound in bridge work. 
 
 It is hardly necessary to say that the plaster and cement must be mixed dry 
 beforehand, and so thoroughly that when patted down with a spatula no particles 
 of plaster are distinctly recognized. To obtain the best results, this material must 
 be worked thicker than plaster. 
 
 SEPARATION 
 
 On separating the impression from the model, if the former when poured is 
 jarred down well, the model will present a finished surface. The part of the model 
 the plate is to cover is now rubbed well with soapstone. This gives the model a 
 metallic luster and a surface very desirable to cast metal against. 
 
 WAX 
 The model is now covered with a new, clean piece of common yellow base-plate 
 wax and care taken that it is of even thickness throughout, and that it has not buckled 
 on the ridge in the median line. The wax is now trimmed as you wish the plate to be, 
 and care taken to cut it low where the depressor muscles have action, usually in the 
 region of the first bicuspid. The outer edge of the wax is now stuck to the model all 
 the way around with a dry, sizzling-hot spatula, held at a right angle with the wax. 
 A strip of wax 3-lG of an inch wide is now cut lengthwise from a sheet of wax and 
 laid down flat on the wax model, even with the edge, except near the heel of the plate, 
 where it is brought over to the lingual surface. The wax strip is brought as near 
 the top or bottom of the ridge on the palatal or lingual surface as the case will permit, 
 the idea being to do away with as much rubber as is possible. The outer sixteenth 
 of this strip is now made a part of the wax model by thrusting a dry, hot spatula 
 through the strips all the way around until the model is felt beneath. The surface 
 next the outer border of the strip is now filled in with wax and smoothed up with a 
 chip l)lower and alcohol lamp, care being exercised to leave the inner edge of the strip 
 sc|uare. At this point lower the temperature of the wax, which has become soft by 
 working, by dipping model and all in water that is not cold; then, with a dull instru- 
 ment, raise the inner border of the wax strip all the 7vay round, as is shown on right 
 side of Model No. 1. It should be lifted away most near the canine eminence and 
 the lingual border of the heel. If this is done right, it affords all the attachment 
 necessary. Sometimes it would be impracticable to use the strips on the labial border; 
 
198 • PRACTICAL MANUAL OF DENTAL CASTING 
 
 it can be done away with altogether, and for the attachment of the rubber, loops of 
 German silver or aluminum can be set in place on the wax and cast successfully. Of 
 course, there is no union of the metals, but they are held in place mechanically tight 
 enough to serve their purpose. 
 
 If you desire to cast directly on the teeth, the front is left open for the pink 
 rubber, and a space of one-half to one millimeter left between all the teeth. This is 
 imperative, because the contraction of the alloy or metal used in casting the teeth 
 would all be checked or broken off. 
 
 The model is now trimmed even with the heel of the plate and a little roll of wax, 
 about the size of a slate pencil and about three inches long, is stuck on the model 
 with a hot spatula, even with and joined to the wax plate. Don't lay this piece of 
 wax over on the wax, as it will not facilitate casting, buf will be difficult to remove 
 in the cast. 
 
 The last thing to do before you invest is to cut the model all over to get rid of 
 the "slazy" surface it has taken on from handling, rubbing with soapstone, etc., 
 so it will unite, so to speak, with the investment, and put it in a bowl of cold water. 
 The flask is a No. $ Hoosier cowbell, and will cost you seventy cents. 
 
 The strap at the top of the bell is placed in a heavy vise and removed. The 
 rivet that holds the clapper is filed off some and driven out with a punch. A one- 
 eighth inch hole is bored a half-inch from the mouth of the bell at its extreme width 
 on either side, to afford attachment for three feet of bailing wire, and you now have 
 a plate-casting machine, as shown in the cut. 
 
 INVESTING 
 
 To invest: Begin mixing your home-made investment compound, and while it 
 is thin, remove the model from the water and with a camel's hair brush fill in the 
 grooves made by lifting the wax strip; then, working quickly, mix the investment 
 thick and pour it in the cow-bell (it should be not quite two-thirds full), now put in 
 the model; then, by holding the cowbell between the thumb and three fingers of 
 either hand, the index fingers are left free to push the model down; it should be 
 jarred and pushed down until the model is about an inch below the surface, or, say 
 until the fingers are in the investment to the first joint. Now remove the fingers, 
 and by pressing on the wax pencil the model is kept in place while the jarring is 
 continued until the surface of the investment is even. 
 
 The surface now presents a semi-liquid appearance which is immediately 
 sprinkled with the dry investment to hasten the setting. In a very few minutes the 
 top of the investment is scraped with a large vulcanite scraper (no attention is paid 
 to the wax pencil, it being cut or twisted off and scraped down with the investment); 
 until it is firm and solid. Then the investment, from an inch to an inch and one-half 
 on all sides of the wax is lowered about one-half inch and the whole top washed out 
 to get rid of any small particles that might fall into the investment and cause a hole 
 in the plate. 
 
 The bell is now placed on a slow fire and the wax burned out. 
 
 This idea of the disappearing model, of course, belongs to Dr. Taggart, and it is 
 to him all credit should be given should this article prove beneficial to you. 
 
 The burning of the wax usually takes an hour or more. When the bell can be 
 removed from the fire and there is absolutely no smoke issuing from it, you are ready 
 to cast. The flask does not have to be ver}' hot, and for this reason a very good 
 cast can be made over' a common plaster-paris model. If you are going to cast 
 
CAMPBELL'S COW-BELL METHOD OF CASTING PLATES 199 
 
 directly on the teeth, the method of investing and removing the wax is also a little 
 different. The teeth are painted with whiting to prevent any excess of the metal 
 adhering to the porcelain, a phenomenon that occurs that to me is very striking. 
 An attempt to remove a film of the aluminum that may have run over one of the teeth 
 without whiting means to remove just so much of the porcelain. 
 
 Place the flask on its side in a clean vessel and fill with cold water until it is 
 covered two or three inches, set on a slow fire and bring to a boil until the wax is all 
 out. Place on fire as before and heat slowly, but in this case, before you cast, the 
 case must be heated pretty hot to bring the temperature of porcelain up to something 
 near the temperature of the molten metal. 
 
 To cast, the cowbell is laid on one side with the mouth elevated an inch or so. 
 An ingot of pure aluminum, or Aerdentalloy, is then laid in the mouth of the bell 
 and melted with a common gasoline blow-pipe. As the metal melts the bell is raised 
 and it runs over the hole left by the wax. This is done for two reasons — first, to 
 keep out any small particles that might fall into the mold, and to give you better 
 access with the blow-pipe until the metal is thoroughly melted "and a little bit 
 more," then, without hurrying, but rather on the pokey order, lay aside the blow- 
 pipe, take hold of the bale, already cold, and get where you will have plenty of room; 
 swing the bell back and forth like a pendulum once or twice and then over your head, 
 like you would a small bucket of water. The plate is cast, of course, the first round, 
 but the swinging should be kept up half a minute, so that crystallization may take 
 place under pressure. All casts made in this manner are better on account of their 
 closer molecular construction. 
 
 The flask is now allowed to cool and the investment and plate shaken out; 
 the excess cut oflf with a hack-saw and the plate finished. 
 
 The impression can be waxed up or the model scraped down at this point, but 
 it is purely guess work and unscientific. As a last resort, when the plate is cast and 
 still needs to be raised at this point, a plaster model of the plate is poured, and when 
 very hard, removed and scraped down as far as you want the plate. The plate 
 is then placed back on the model and with a ball hammer beaten down to place. 
 
WILSON'S CAST ALUMINUM PLATES 
 
 By George H. Wilson, D.D.S.. Cleveland, Ohio. 
 
 1. Cast of silica sand, wash silica and plaster of Paris, equal parts by measure. 
 Base-plate of paraffin built up with pure yellow beeswax, showing stages of con- 
 
 Waxed impression, showing method of waxing 
 
 Finished casting 
 
 Casting as it came from investment 
 
WILSON'S CAST ALUMINUM PLATES 201 
 
 Showiiu^ uhiniimiin cast to teeth on palatine surface 
 
202 PRACTICAL MANUAL OF DENTAL CASTING 
 
 struction; also the sprue formers. The pouring sprue must not exceed 3-16 of an 
 inch. 
 
 2. Casting as made in the BiUmej^er bucket. 
 
 3. Finished pure aluminum base-plate. 
 
 4. Complete denture mounted on Snow antagonizer. The upper is cast direct 
 to the tooth. This is not practicable with platinum pin teeth, as aluminum is a 
 solvent for platinum. Attachment of the teeth with vulcanite is the practicable 
 and desirable method as exemplified in the lower denture. 
 
 SOME PHASES OF THE CASTING PROCESS 
 
 By C. S. Van Horn, D.D.S., Bloomsburg, Pa. 
 
 To test a pattern wax hold a piece in the mouth until it assumes body temper- 
 ature, when, if it becomes plastic, susceptible to change on moderate pressure either 
 by the teeth or fingers, it is not suitable for the purpose for which it was designed. 
 There is a long train of maladies attending the use of a plastic wax that may be 
 largely or entirely eliminated by the use of a non-plastic wax. 
 
 Assuming the cavity to be approximo-occlusal, involving all or part of one or 
 more cusps, either of bicuspids or molars, the wax, which has previously been softened 
 in water at 183 degrees F., is quickly thrust into the cavity and molded quickly to 
 place, and the patient directed to bring the teeth into normal occlusion, when with 
 the fingers and proper instruments the buccal surplus is pressed into contact with the 
 buccal wall of the cavity, the instrument being pressed into the interproximal space, 
 thus forcing the wax into contact with the cervical margin of the cavity. As a 
 generous surplus of wax has been used we have a rather uninviting appearing mass, 
 which is soon reduced by rough carving to something like normality. In carving it 
 is of the utmost importance that the pattern remain stationary in the cavit3^ i. e., 
 without moving and rubbing against the cavity wails; the best way to prevent this 
 is to carve the occlusal surface before disturbing the contact of the pattern with the 
 adjacent tooth. The support given to the pattern by the adjacent tooth, together 
 with properly directed force in carving, enables us to make the most extensive restor- 
 ation with seldom an appreciable movement of the pattern. After the occlusal 
 surface has been carved, our attention is directed to the lingual margins, then to the 
 buccal margins, and lastly to the cervical margins, all these margins being finished 
 flush with the square tooth-margins for reasons previously described. 
 
 We now have a pattern — not an impression — carved to form, except that it has 
 a contact surface — not point — with the adjacent tooth, and is unpolished. The 
 polishing should be done in the same order as the carving; First, the occlusal surface 
 is gone over, touched where necessary with the carving instruments to bring out any 
 artistic lines, and highly polished; then the lingual and buccal margins. Then with a 
 pellet of cotton wet with cold water and held against the occlusal surface to prevent 
 any movement of the pattern, a hot, very thin flat instrument is passed between the 
 adjacent tooth and the pattern, and the abnormally large contact surface converged 
 into a normal contact point, and polished with a wisp of cotton, the teeth having 
 been previously separated, as they always should be, to admit of a subsequent 
 normal contact being formed. 
 
 If all the steps have been followed with precision and a high regard for artistic 
 attainment, we have a beautiful restoration of the lost part in wax. 
 
SOME PHASES OF THE CASTING PROCESS 203 
 
 To extricate the pattern an explorer is usually employed, though any of the 
 well-known methods may be used, being especially careful to prevent the slightest 
 marginal distortion. Here again it is of advantage to have square margins where 
 sheltered, for it is manifestly easier to remove without distortion a pattern with 
 square, well-defined margins than it is to remove one with feather-edges. The 
 pattern is then attached to the sprue and examined under a magnifying glass co as- 
 certain its perfectness, and if it is found to be flawless in iis marginal impressions 
 any carving which may be deemed essential may be done on the cavity side — and I 
 might say right here that it is seldom that the cavity side of the pattern should not 
 be carved, believing that by so doing we increase the efficacy of the finished product. 
 This carving on the cavity bide may be easily and expeditiously done with a light, 
 sharp lancet or a bur in the engine, or a combination of both. The finishing touches 
 being completed, the pattern is ready for investing. 
 
 INVESTING 
 
 It is just as essential that the investing be properly done as any other part of the 
 procedure. I have noted that some use scales, others measures to apportion the 
 investment and water. I am not prepared to comment on this procedure, except to 
 say that at present I use neither. The investment should be mixed just as thick 
 as it can be and yet admit of the pattern being properly invested, and as it requires 
 more time to coat a complex than it does a simple pattern, it is obvious that the 
 investment should be mixed accordingly. Then, too, some are more dextrous than 
 others, being capable of working with a much stiffer mix. Personal equation being 
 such a potent factor in all our work makes it next to impossible to formulate laws 
 for operative procedures in the field of dentistry. 
 
 Ten to fifteen minutes after investing the pattern the investment is, or should 
 be, sufficiently hard to admit of the sprue being removed, which should be done by 
 heating the sprue to a full red heat for several minutes and twisting it out with 
 pliers, thus preventing any distortion of the mold. Remember that we are dealing 
 with the investment while in a semi-set condition, and great care is essential to 
 success. 
 
 The flask is immediately placed over a very low flame, a flame of just sufficient 
 heat to drive out the moisture without creating steam, and as soon as the investment 
 is dry the flame is increased and the wax burned out. Formerly, the investment was 
 allowed to dry over night, but 1 believe this to be at variance with scientific findings 
 relative to the setting of plaster of paris, one of the ingredients in the investment. 
 Be this as it may, I obtain better results by placing the "green" investment over a 
 low flame ten to fifteen minutes after flasking — the castings are just as smooth, just 
 as sharp, and without "feathers." 
 
 CASTING 
 
 It is obviously impossible to go into extended detail of casting without consider- 
 ing the numerous devices that have been placed upon the market for the purpose, 
 and this in itself would require a paper of considerable length. My advice, therefore, 
 is after mastering cavity preparation and formation, to master the complete tech- 
 ni(|ue, and then it is time to master the device with which you expect to do the casting. 
 I fear that a great man\ ha\e fallen and that more will fall by the wayside by be- 
 ginning at the reverse end. That which go(;s to make up the entire casting problem 
 is by no means easy of solution, nor suited to perfunctory methods or desultory 
 application. 
 
204 PRACTICAL MANUAL OF DENTAL CASTING 
 
 At present our work in this field is largely cni|)irical; wc lia\e not practiced 
 castina; sufficiently long to have established it on a scientific basis, consequently we 
 are too many times between the devil and the azure brine to know the how and the 
 why. Some day the clouds will clear, and we shall broaden our horizon and place 
 casting on a scientific basis. Then we shall have what we have not now, a perfect 
 casting machine, a machine which will be automatic in its action, indicating the exact 
 pressure on the gold in the mold and at the same time the temperature of the metal, 
 just as our pyrometer furnaces indicate the temperature of the porcelain. This 
 together with a perfect pattern wax and a perfect investment rhaterial will have a 
 powerful influence in eliminating stumbling blocks in the paths of those not especially 
 adapted or reasonably versatile. 
 
 The two most important considerations, with the present machines arc to de- 
 termine the requisite pressure and the proper state of fluidity of the gold. Too 
 much pressure will expand and crack the investment, causing an imperfect casting, 
 and if the gold is not sufficient!}' fluid a sharp casting is not to be anticipated. 
 
 No machine of which 1 have any knowledge will give an exact, sustained, de- 
 terminable pressure on the gold in the mold, arid with the machines of the "plunger" 
 type it is risky, if you have a regard for veracity, to hazard a guess on the pressure. 
 Therefore, no difference what device you use, experiment until you have mastered it, 
 and by that time you will have discovered that the more fluid the gold is at the time 
 when force is applied, the shai-per the casting will be. 
 
 One way of determining the proper state of fluidity of the gold is this: First 
 the gold assumes a globule, then the "bull's-eye " appears, and finally we get what may 
 be termed the sun-glow. When this stage is reached, if you are watching the gold 
 very closely, 3'ou will notice a very slight spreading and flattening of the globule; 
 this is the time to put on the pressure, and if it is done properly, and if 24k. gold in 
 very generous quantity — a quantity admitting at least 5 dwt. surplus — is the metal, 
 you may be reasonably certain of success, though on rare occasions failure will stare 
 you in the face. But, since it is in degree by our failures that we advance, they are 
 not always to be despised but rather viewed as stimulants to subsequent success 
 through fathoming the cause. "If at first you don't succeed." ascertain the cause, 
 for the effect will follow in natural sequence. — Cosmos. 
 
THE WORKING MODEL FOR INLAY PRACTICE 
 
 By H. W. Arthur, D.D.S., Sc.D., Pittsburg, Pa. 
 
 1 1 is not the purpose of this paper to advocate the use of the working model to the 
 exclusion of the direct rqethod of practice in making inlays. 
 
 The working model method, aside from the fact that it is not so expeditious, has 
 otherwise all the advantages, as well as supplying the means of overcoming difficulties 
 attending the direct method of practice. In any and all cases, an accurate adap- 
 tation to the cavity with contact and occlusion, in bicuspids and molars, as well as the 
 more simple cases, can be assured by the working model method. The working 
 model, while specially to be preferred, for the production of porcelain inlays, meets 
 all the requirements for gold inlays. With the working model as it should be, that 
 is, an accurate impression of the cavity, the appro.ximating tooth and the correct 
 occlusion, the operator, in this class of cavities, has control of conditions and the 
 manipulative procedure in a way that he cannot have by the direct method. 
 
 Having the porcelain inlay specially in mind, the following advantages may be 
 claimed for the working model: 
 
 The cavity can be approached conveniently from all directions, so that the 
 platinum matrix can be more readily adapted. 
 
 The porcelain material can be applied with the platinum matrix on the model, 
 thus avoiding the liability to change of form to which the matrix is subject when 
 held in pliers. 
 
 Proximal contact and accuracy of occlusion can be gauged on bicuspids and 
 molars, and more readily attained with the anterior teeth. 
 
 Several inlays (there need be no limit to the number) of different shades may be 
 made with but little more expenditiux of time than for one, thereby giving a choice 
 of the one best suited to the case. 
 
 It supplies the means, in case of an accident, of repeating the operation without 
 annoyance to the patient. 
 
 Nicety of detail can be worked out at leisure. 
 
 The model, properly registered, with shade record, may prove convenient for 
 future use. Aside, we might add, that the temptation to insert a "good enough" 
 inlay cannot be so readily excused. 
 
 The above will apply equally to the gold inlay, where the procedure is in common. 
 
 To insure the best results, the working model must be an exact reproduction of 
 cavity and surroundings, as found in the mouth. This necessitates that, not only 
 should the impression be accurate, but that there should be no change of bulk of form. 
 Experience has demonstrated that modeling composition and copper amalgam 
 supply the materials that meet these requirements. Where there is direct access to 
 a cavity, a good impression can be taken by the simple method of shaping the modeling 
 composition to a point and then softening the point. This, with the harder composi- 
 tion to give resistance, can be forced to all parts of the ca^•it^• and cavo-surface angle. 
 
20(5 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 In most cases, however, a suitable ca\ity tray is necessary to give resistance to 
 force the impression material to the distant parts of the cavity and cavo-surface 
 angle, as at the cer\ical margins of proximal cavities and under the gingiva-labial 
 surfaces. 
 
 To meet these requirements your essayist has contrived a number of cavity 
 trays, described as follows: 
 
 No. 1. Designed for taking impressions under the lahio-gingival margins of 
 the anterior teeth. 
 
 Xos. 2 and 3. Designed for taking impressions (rights and lefts) of the prox- 
 imal cavities, mesial and distal, of the anterior teeth. 
 
 Nos. 4 and 5. Designed for taking impressions of mcsio-occlusal and disto- 
 occlusal cavities of bicuspids and molars. 
 
 No. 6. Designed for taking impressions where the lingual or buccal portion 
 of a tooth is wanting. 
 
 No. 7. Designed for taking impressions of labial, buccal or occlusal cavities. 
 
 No. 8. Designed for taking impressions of disto-occlusal cavities of third 
 molars, including the occlusion. 
 
 A- more recent device has, in a measure, taken the place of Nos. 4 and 5. It is 
 designed not only to take an impression of the cavity, but includes proximal contact 
 and occlusion. So that, mounted on the articulator, we have all the conditions of 
 the mouth. 
 
 The device is simple, designed to confine the impression material; can be made 
 in a few minutes. The same appliance has been used by your essayist as a matrix 
 in the operation of filling for years. It co.nsists of a thin piece of sheet metal, shaped to 
 pass above the cervical margin and around the embrasures of the tooth, with a lip 
 turned down to rest on the ridge of the proximating tooth. The appliance, when 
 in place on the proximating surfaces of bicuspids or molars, as the case may be, 
 
THE WORKING MODEL FOR I NLA Y PRA CTICE 207 
 
 should be wedged lightly at the cervical portion with cotton, where there should be a 
 slight yielding, so that the impression material may pass over the margin of this 
 portion of the cavity. 
 
 The lip resting on the ridge of the proximate tooth prevents the forcing of the 
 appliance onto the gum when taking the bite. The parts of the appliance passing 
 around the embrasures should be free and yet not enough so to allow the impression 
 material to pass around the embrasures to the extent that it will interfere with the 
 withdrawal of the impression. 
 
 Sufficient impression compound should be used to fill the cavity and cover the 
 occlusal surfaces of the adjacent teeth. The patient should be instructed to bite 
 and give lateral motion. With the impression in hand, copper amalgam is prepared 
 for inserting in the usual way. It should be inserted with care, pressed well onto the 
 thin margins, ox'cr the impression of the ca\'ity and embrasures, and well onto the 
 occluding surface of the tooth. It is better to wait until the amalgam has hardened 
 before completing the mounting on the articulator. 
 
 On the articulator the slight obstruction to exact occlusion, caused by the lip 
 of the matrix, is corrected in the absence of the obstructing lip. 
 
 The thickness of the matrix doesnot interfere with securing the correct proximal 
 contact. The working model should supply all the conditions of the mouth; it has, 
 in addition, all the aforesaid advantages for manipulations. 
 
 The appliances we have described are so readily made, and the taking of an im- 
 pression so simple, that it is well to have it at hand, even though it ma^' only be for 
 contingencies. 
 
 Where the occlusion and contour can be allowed, as in the anterior teeth or on 
 exposed surfaces, the copper amalgam counter of the impression of a cavity can be 
 mounted in plaster in a suitable receptacle, thus supplying a convenient means for 
 forming the platinum matrix by the use of the water bag, under screw pressure, and 
 for correcting the shape of the matrix, if need be, after the first fusing of the bod^- in 
 the matrix. 
 
 The convenience of the working model for making gold inlays is too ob\'ious to 
 enlarge upon it. 
 
 Having as an object the insuring of the best results, as a means to that end, the 
 working model has a place not only in inlay, but in other lines of practice. 
 
 ABSTRACT OF DISCUSSION 
 
 Dr. Frank L. Wright, Wheeling: I should like very much to have seen a copy of Dr. .\rthur's 
 paper. I have never used copper amalgam. I have used Dr. Weston A. Price's method of artificial 
 stone, which is perhaps not as good, but I have had some very good results, especially in proximal 
 cavities between bicuspids and molars. I have made four fillings at one time, using artificial stone; 
 separating a little to get the contact point, and have had results in fillings dropping right into place 
 with a beautiful contact point. The advantage of any model is the almost complete finishing of your 
 filling before putting it in the mouth. You can polish the filling on the artificial stone down to a very 
 fine edge, with little extra work necessary after cementing your filling. The only method I am familiar 
 with is the Dr. Price method. He has different little impression cups for taking impressions. He uses 
 a wax, and the artificial stone is mixed up and put in the wax after it hardens, and the stone does not 
 harden until after heat is applied, and you can make a good model in that way. Your casting wax 
 is then molded right into your cavity, contouring it the same as Dr. Arthur has told us about; and you 
 can get perfect occlusion. Finish your filling, and if you have two or three proximal cavities using his 
 articulator, breaking your model apart. It is nicely adjusted so it can be opened for contouring, 
 graded down to the milometer; spread your teeth just a little and your fillings will go in in verj- nice 
 shape. 
 
 Dr. L. G. Beerbower, Terra Alta: I am sure we have all appreciated this paper very much and 
 
208 PRACTICAL MANUAL OF DENTAL CASTING 
 
 will yain many splendid points from it, but I have not used the method enough, have not endeavored 
 to put it into practice, to discuss it. I know it is a good method from a common sense standpoint. 
 
 Dr. Arthur (closing) : I have endeavored to put it into as few words as possible and make it as 
 plain as possible. I claim considerable originality in what I have produced there, and I am satisfied 
 when you see it in clinic you will see that it is a valuable means in producing results. That is what we 
 are after. 
 
 As to Dr. Price's method, I know of it; have practitioners nearby who follow it up, but think my 
 method is simpler than Dr. Price's and have something in reserve. In Dr. Price's you break up j'our 
 model, but I have had the impression that in breaking that up you are likely to injure your filling. 
 I regard it as a good method; I wouldn't place this method in contrast with it at all; I am .satisfied that 
 it is good and have been prompted to take it up, but have not just done so, probably because of my 
 own scheme. 
 
 CONDUCTIVITY OF CAST INLAYS 
 
 By S. H. Guilford, D. D. S. Philadelphia 
 
 The clanger of pulp irritation and often the devitalization from placing a metal 
 filling in contact with a thin layer of dentin overlying the pulp has long been recognized 
 and, in a measure, guarded against by interposing some less conductive substance 
 between the two. 
 
 For this purpose different materials have been used, such as a coating of varnish, 
 a layer of paper or asbestos with some adhesive and non-irritating medium to hold 
 it in place, and either alone or in connection with any of the foregoing, a layer of 
 one of the cements. 
 
 These have answered their purpose remarkably well in connection with foil 
 fillings but only the last one has been found really available when cast inlays are used. 
 
 If the employment of an intermediary is deemed essential under a foil filling in 
 large or deep cavities, an even thicker layer of non-conductive material is necessary 
 under an inlay to insure subsequent comfort and guard against pulp devitalization. 
 
 However dense a foil filling may be it is never so dense as an inlay. The former 
 contains a portion of air between its particles and air is one of the best non-conductors. 
 In the latter the molecules are more closely in contact and thermal changes are in 
 consequence more rapidly transmitted. 
 
 In this fact lies one of the chief dangers in the emplo^'ment of the cast inlay. 
 Another fact worthy of consideration is that a gold filling may be removed piece- 
 meal if for anj' cause the tooth should be sensitive to thermal changes after being 
 filled. A cast inlaA^ could not thus be removed and would have to be pried out 
 with wall fracture as an almost certain result. 
 
 We therefore feel that the necessity for providing against thermal shock under 
 cast inlays should be strongly emphasized. 
 
 It has been a common practice, in deep cavities, to partially fill them with cement 
 and then give to this material and the adjacent walls the shape necessary for the 
 placing and removal of the wax inlay form. This is a good practice and in many 
 cases has to be resorted to, but it takes time, and delay's the completion of the 
 operation. 
 
 A better plan, in cases where caries has not made too extensive inroads, is to 
 remove only the softer portions of decay and prepare the cavity so that the wax 
 form will draw, at the same time shaping all margins in the most careful manner 
 just as we wish them to remain. 
 
 After the inlay is constructed and ready to insert the inner portion of the cavity 
 is further excavated and prepared in the usual manner. The removal of this last 
 
CONDUCTIVnV OF CAST INLA VS 2Un 
 
 portion of decalcified material forms a space for the cement to occupy when the inlay 
 is set. But this is usually not enough. The wax form after its removal from the 
 cavity with the sprue-wire firmly imbedded in it should be reduced in size on its 
 cavity side so as to provide greater space for the non-conducting cement. 
 
 This is an exceedingly delicate operation owing to the danger of distorting the 
 form and rendering it useless. To trim it with a cold spatula or bistoury would 
 necessitate the application of too much force. A heated spatula would be liable to 
 melt too much of the wax and cause it to flow and ruin the form. Heat, however, 
 seems to be the most available medium for the purpose if some means be provided 
 for carrying away the wax as fast as it is melted. For this purpose a coujilc of de^'ices 
 lia\c Ix'en placed on the market consisling of a liandlr with a bull) or receptacle 
 near its (juter end and a metal or glass capillary tube leading from it. TIu' liandle is 
 hollow and connected with an exhaust pump of some form. 
 
 When the bulb is heated the free end of the small tube is applied to the portion 
 of the wax form to be removed and as it melts is drawn by suction through the tube 
 into the bulb where it is absorbed by the cotton. 
 
 A device of this kind serves its purpose admirably but it lacks simplicit}. .An 
 equally efficient method, but far simpler, has been suggested by someone and adopted 
 by the writer. It consists of an old excavator from which the point has been broken 
 and the shank slightly roughened with a file. If cotton is wrapped in a spiral about 
 the point for half or three-quarters of an inch and the shank heated some distance 
 farther back, the point, when applied to the wax form, will melt it and the cotton 
 instantly absorb it. 
 
 In this way, with deft handling and the occasional renewing of the cotton, any 
 quantit}' of the wa.x form may be removed, and any shape given it. In fact, the wa.x 
 which is usually convex on its under side, may, by this method, be made concave or 
 partially hollow, which will not only materially lessen the amount of gold used, but 
 also aid considerably in its retention. 
 
 The main object, however, in rcmo^'ing a portion of the wax form is to pro\'ide 
 space for a greater quantity of the non-conducting cement. 
 
 The writer has also found it of advantage to groove the wa.x form for retention 
 purposes instead of doing it later on the cast inlaj-. To do it after the gold has been 
 cast is a delicate operation sometimes resulting in twirling the small piece out of the 
 fingers onto the floor and occasionally wounding the fingers when a small circular 
 saw is used. 
 
 Grooves are easily cut in the wax form, if the sprue-wire is firmly attached to 
 it, by drawing a fine exca\'ator along the surfaces to be undercut. A fine bead will 
 be raised on each side of the groo\e but this is casih' remoAcd from the gold surface 
 after casting. 
 
 With the rapidly extending use of the gold inlay, improved methods of renio\'ing 
 surplus wax from the form and of grooving its sides will probably soon be evolved 
 from the brains of the man^' who are concentrating their thoughts upon the further 
 development of this most valual)le method of tooth preservation and restoration. 
 
 — The Garrelsonian. 
 
METHOD OF REPRODUCING FLOWERS, INSECTS AND 
 THE LIKE BY CASTING 
 
 By T. C. Hutchinson. D.D.S., Decorah, Iowa. 
 
 As time goes on the science of art and invention are making rapid strides towards 
 producing wonders in the mechanical Hne, all for the benefit of man, to aid him in 
 accomplishing work more rapidly, in doing it better, and at the same time making 
 work easier on the man. This is certainly an age of invention and the dentist who 
 thinks that he knows all about the casting of inlays, crowns, etc., has yet something 
 along these lines to learn. 
 
 With the invention of casting, as brought out by Dr. Taggart, the dentist does 
 his work more rapidly and in the hands of the average man, more perfectly, than by 
 the use of former methods of accomplishing the same results. The dentist has more 
 time in which to rest and occupy his time with things of interest, and the writer 
 knows of nothing that would give him all of this, better than the making of metal 
 
METHOD OF REPRODUCING FLOWERS, ETC., B Y CASTING 21 1 
 
212 PRACTICAL MANUAL OF DENTAL CASTING 
 
 flowers, etc. To practice this worlv you will not only find pleasure in the work but 
 you are bound to learn something relative to your work in casting plates, etc. The 
 illustrations here presented of the cast figures will give you an idea of its possibilities.. 
 
 In a few words I will tell you how to go at it: Take any flower, no matter how 
 delicate it may be, and immerse it in a mild solution of sandarac varnish, shaking the 
 surplus off by taking hold of the stem; then mix the investment material, and with a 
 camel's hair brush paint the top of the petals as you would your wax inlay. Next, if 
 it be a flower of several petals, pour some of the investment material in the palm of 
 your hand and lay the flower in this and pour more investment over it; jar your hand 
 and the investment will fill up all of the interspaces. (Note that the coating of 
 sandarac attracts the moisture of the material.) Having poured some investment 
 in the bottom of your flask, take the partially invested flower by the stem and lay 
 in the flask and then pour the flask full. Use the stem of the flower for the sprue. 
 Make the crucible form for 3'our metal the same as for inlay work. 
 
 In burning out the flower, which is placed as close to the bottom of the flask as 
 possible, put your blast heat on the investment instead of the flask. You will have 
 to make a cast flower to learn how to ascertain the time required to burn it out. With 
 the heat directed near the flower one should not consume much more time than it 
 would take to burn out the same amount of wax. 
 
SOME MORE PROGRESSION 
 
 By R. C. Brophy, M.D., D.D.S., Chicago, III. 
 
 The dental profession is a progressive body. It may be that some of its mem- 
 bers did not vote the Bull Moose ticket at the late election, but it is probable that if 
 they did not, they voted for Mr. Wilson through a belief that he is just as progressive 
 as is Col. Roosevelt. 
 
 Especially are dentists, as a body, progressive in considering new ideas pertain- 
 ing to practice. Very few innovations are introduced that are not followed by a 
 general looking up and taking notice, and a general manifestation of a purpose to 
 investigate; but when a new idea has been tested and found worthy of adoption, 
 they exercise no less progressiveness in acquiring the best facilities obtainable for 
 the application of that innovation in their work or practice. 
 
 It has been observed by a good many, however, that while dentists are actuated 
 in their progressiveness in adopting new methods of practice by a desire to subserve 
 
 the best interests of their patients, when it comes to the matter of doing the work 
 their progressiveness is actuated by pure, all-wool-and-a-yard-wide selfishness. 
 For instance. Dr. j. C. Y. Moore, of Aurora, 111., believes, with a great many of his 
 brother dentists, that the best way to conserve the interests of patients who have 
 decayed teeth, in a large percentage of cases, is to make and insert inlays in the 
 cavities, and he does it. 
 
 Dr. Moore, one day, made an inlay, and was intently at work finishing it to the 
 degree usually considered before insertion, when it flew from his fingers and alighted 
 through an aperture of a floor register. Dr. Moore, just at this time, began to forget 
 about his patient, and commenced to think about Dr. Moore. The inlay was re- 
 covered. It was a small inlay, and as Dr. A'loore pinched it harder and as the little 
 disc played upon the inlay and upon Dr. Moore's thumb and finger in a mutual 
 manner, he thought more and more of Dr. Moore. The patient was forgotten 
 wholly, brotherly spirit lay dormant in his breast, and no thought of even floor 
 registers or sore fingers, other than his own, entered or emanated from Dr. Moore's 
 mind; but the idea was then and there born therein that he would try to make some 
 
214 PRACTICAL MANUAL OF DENTAL CASTING 
 
 kind of a holder that would hold Dr. Moore's inlays while being finished. Dr. 
 Moore did set about it, and the process of evolution finally developed a perfectly 
 practical instrument, an efficient little device for that purpose. 
 
 It was a clear case of progress being pushed ahead by pure, unbridled selfishness. 
 No consideration of the uplift or maintenance of p.itients' interests nor of anyone 
 else's interests save Dr. Moore's, had a thing to do with the pushing. 
 
 As a matter of fact, the latent disposition of Dr. Moore to be of service to his 
 brother practitioner by offering to let him share the benefits of his instrument would 
 have continued to sleep had it not been for the persuasion of the writer. 
 
 It would be all right sometimes, and, as a matter of fact, would be better lots of 
 times for a man to hide his light under a bushel, but it is positively wrong for a 
 member of the Christian-spirited profession of dentistry to keep as good a thing as 
 Dr. Moore's inlay vise out of the hands of his professional brother. He might let 
 him chase the festive collar button down his back, under the dresser, or any other 
 place, but he should not let him chase the inlay, if he can prevent it, as Dr. Moore 
 can do. 
 
 The cut shows the two styles of Dr. Moore's vise. The one at the right com- 
 prised by his willing but inappropriate fingers, which he condemned, and abandoned, 
 and the one at the left, much simpler in construction, yet excelling it in every es- 
 sential, which he has substituted therefor. 
 
 It is unquestionable that dentists feel that if they had an instrument which 
 would hold inlays of every size and every form in a perfectly rigid grasp on the end of 
 a handle nicely fitting the clasped hand, and thus holding it without contact with 
 the fingers or obstructing the view, operate upon the outer surface and margins, a 
 long and urgent need would be met. 
 
 Having been instrumental in getting Dr. Moore to make his instrument avail- 
 able to the profession, I am writing this because I regard it equally important that 
 attention of the profession be called to it. 
 
HOW TO OBTAIN A SMOOTH, DENSE SURFACE ON CASTS 
 
 By F. L. Olds, D.D.S., Toledo, Ohio. 
 
 To insure smooth, dense surfaces on plaster casts, also on casts made of invest- 
 ment materials, we recommend that impressions of all-plaster be used; or, if modelling 
 compound or wax be used, that a thin layer or coating of plaster be applied to the 
 surface of the impression. 
 
 To prepare the impression for pouring a model of model-plaster (New York 
 plaster), for vulcanite work, first give the impression a thin coat of shellac varnish. 
 When this has become dry, which it will in about thirty minutes, give the impression 
 a thin coat of sandarac varnish. This also should be given time to harden, about 
 twenty minutes, after which we place the impression in water and allow it to become 
 saturated before pouring the model. As an experiment, take any piece of plaster 
 that has been lying around the laboratory for a few hours, and put it in water; 
 bubbles will rise on the surface very freely, even through a varnished surface. Now, 
 if freshly-mixed plaster or investment material were placed in a dry impression, the 
 same thing would occur; bubbles would come from the surface of the dry plaster and 
 a model full of holes, forced in by these bubbles of gas, would be the result. The 
 reason for using the varnishes, as stated, is that the shellac acts as a filler on the 
 fresh plaster surface, just enough being used to fill the pores and stain the plaster 
 to a slight depth, leaving the surface, so far as the fine lines of the impression are 
 concerned, just as it was before varnishing. 
 
 If the impressionweretobepouredatthisstage, with just the shellac as a separating 
 medium, there would be difficulty in separating, as the plaster, in setting, creates 
 enough heat to soften the shellac and thoroughly glue the two parts together. 
 
 Some are in the habit of using oil or soap to prevent this sticking together of 
 ihe impression and model, but this is not good practice, as the oil or soap will unite 
 with the fresh plaster, and a very poor surface on the model is sure to be the result. 
 So we use sandarac varnish, thin sandarac varnish, as a second coat on the impres- 
 sion. All that is needed is just enough to give a smooth, glossy surface. We prefer 
 a colored varnish, as it is easier to ascertain just how much is being used. 
 
 When the varnish has hardened, place the impression in water and leave it there 
 until saturated, so that no bubbles of gas will rise up and fill the surface of model 
 with the holes that we all have seen, and so that the dry plaster will not take up some 
 of the necessary water from the fresh plaster, and give us a porous surface of poor 
 quality. 
 
 Sandarac varnish is practically inert so far as the pouring of impressions is 
 concerned and can be separated by carving away the impression over the ridge until 
 the stain made by the shellac appears; then place the point of a knife under the edge 
 and gently break away from undercuts and around teeth. 
 
 After separating the impression, the first thing to do is to give the surface of the 
 model a good coat of castgloss, or silex, before anjiihing else gets onto the surface. 
 
216 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Hot wax or grease of any kind, if run over the surface before applying silex prepara- 
 tion, will prevent the plaster from taking up the silex, and a rough, porous surface 
 on the palate of the plate will result. 
 
 After applying castgloss, wipe the model dry with a piece of cotton, rubbing 
 hard enough to polish the surface somewhat. Hot wax or any other material may 
 now be run over the surface of the model, and the plate will still come out with a 
 smooth, clean surface. 
 
 For models of investing material for casting, we prepare the impression the 
 same as above, with the exception that whatever relief is desired for the case should 
 be carved in the impression; and if it is necessary to fit the plate a little closer at the 
 periphery, just add a little wax to the impression, as the model cannot be carved when 
 made of investment material without making a rough surface. The surface of a 
 model for casting should be left just as it comes from the impression, without any 
 alterations whatever. 
 
 The surface of any model will be just as smooth as the surface on which it is poured. 
 If plaster is poured onto glass, a glassy surface is the result. If poured on a rough 
 surface, the surface will be rough. Therefore, to have smooth models we must have 
 smooth impressions, and the impression must be treated so that it will be practically 
 inert so far as the pouring of freshly-mixed plaster or investment is concerned. 
 
CASTING, WITH SPECIAL REFERENCE TO CASTING ON PORCELAIN 
 
 By W. C. Gillespie, D.D.S., Nashville. Tenn. 
 
 The process of casting metal under pressure has opened the greatest field of 
 possibility for saving and restoring teeth that the dental profession has come into 
 in many years. The casting machine stands next to the dental engine in line of im- 
 provement in dental equipment and in variety of uses to which it may be put. 
 
 There are countless numbers of devices for casting metal under pressure, but 
 all are variations of four basic types — those that utilize centrifugal force, suction, 
 compressed air, or steam pressure. 
 
 The application of pressure casting — a verv' old process — to dental art will raise 
 the general average of tooth-savang ability, practical merit, and artistic product of 
 the profession because it will enable the less skilful practitioners to form in plastic 
 substance and reproduce in metal better dentures than the}' were able to do direct 
 in the more refractory substance. 
 
 Casting is neither an experiment nor a fad; neither can it be conducted on the 
 nickel-in-the-slot basis. A few porcelain facings or teeth and a little scrap gold 
 dumped into the machine before you go to dinner will not be a beautifully finished 
 bridge when you return. Brains are as essential to successful casting as a properly 
 constructed casting machine and necessary materials. 
 
 The limitation of the application of casting depends entirely upon the ingenuity 
 and skill of the one who employs the process in constructing dental restorations. 
 By this means anything of which a mold may be obtained may be reproduced in 
 metal with ease. 
 
 Castings consisting entirely of metal, such as inlays or all-gold bridges, may be 
 produced; or gold may be cast directly in contact with porcelain surfaces without a 
 previous adaptation of backing. A simple inlay or a six-tooth bridge may be cast 
 with the same ease and same amount of labor in so far as the casting is concerned- 
 
 The amount of time required to cast an inlay may be as long or shorter than 
 would be required to condense foil in the same ca\'ity; but the physical labor is not a 
 tenth part so strenuous, and the patient will rise up and call you blessed. More 
 patients ma}' be seen in a day, because when the wax model is obtained the patient 
 may be dismissed and the casting made when there is nothing else to do. 
 
 The advantages of cast gold over welded gold are too well understood to need 
 comment, and where the inlay is preferable to a condensed filling depends entirely 
 upon conditions to be met in each case. 
 
 The time required to construct a bridge by the process of casting is \er\- much 
 less, as a rule, than that by soldering, and the time and labor are just as much less 
 as would be necessary to do the things avoided by the process of casting — namely, 
 greater amount of grinding porcelain bodies, backing, making dies, swaging cusps, 
 waxing cusps in position, coaxing solder to go where \v)u wanted it and grinding off 
 the excess solder yuu knew \(>u did not nt'ctl i)ul wtTe afraid nol to |)Ut tlicre. 
 
218 PRACTICAL MANUAL OF DENTAL CASTING 
 
 The time required to wax up, invest, drj' out, and heat up is the same for either 
 process; but the actual casting requires much less time than building up the amount 
 of solder would do. 
 
 Grant, for the sake of argument, that the time required by both processes is the 
 same for a given case, the results obtained, labor and material saved, and avoidance 
 of fatigue and discomfort to the patient place casting far ahead of condensing fillings 
 and soldering crowns and bridges. 
 
 The dentist who casts only inlays is certainly blind to the possibilities of a simply 
 wonderful and wonderfully simple process which he is employing only in its most 
 insignificant application, as valuable as the process of casting inlays may be. And 
 the dentist who does not cast at all is either utterly non-progressive or too cautious 
 for his own and his patient's best interests. 
 
 The process of casting, intelligently employed, is thoroughly applicable to the 
 construction of shell crowns, all-gold bridges, retaining appliances for regulations or 
 pyorrheal teeth, porcelain-faced crowns, bridges wherein porcelain facings, ordinary 
 rubber-plate teeth, diatoric teeth, saddle-back teeth, removable-pin crowns, or Logan 
 crowns are employed for abutments and dummies and for adapting Logan crowns 
 to roots. 
 
 Any type of porcelain tooth may be cast upon without backing, but care should 
 be exercised not to use a tooth with pins soldered in position or a pin of composition 
 metal that might have a fusing point below that of gold. 
 
 Backing as employed in the old process was to give a surface upon which solder 
 would flow evenly and not ball up. It had little to do with the prevention of check- 
 ing of porcelain, however contradictory that may sound to the teachings and ac- 
 cepted theories of the past. A direct contact of porcelain with heat or flame will 
 not cause checking, provided the cold body is not thrust suddenly into a flame or 
 furnace, but is permitted to heat gradually at first. It may then be carried to a 
 degree considerably above the fusing point of pure gold; and if allowed to cool 
 gradually, no checking will occur, though this be done repeatedly. 
 
 Borax never yet caused a piece of porcelain to check, except indirectly; yet this 
 statement would be regarded as damning heresy bj' the old masters. These things 
 I have proven bj' hundreds of tests and experiments during a practice of nine years 
 and four years' experience with a porcelain furnace. While writing this paper I 
 have had in my electric furnace an ordinary plate molar tooth, a Logan crown, and 
 two diatoric molar teeth, which were rolled in damp powdered borax and placed in 
 the furnace covered with a layer of borax, and the hole in the diatoric teeth filled 
 with it. A nugget of pure gold was placed with them and fused, and the teeth came 
 out without a check, but were most beautifully glazed on surfaces that had been 
 ground with a stone. The borax may unite with the porcelain and cause it to become 
 more brittle if carried very high, but the experiment is cited in proof that it does not 
 directly cause checking. 
 
 Checking of porcelain is more often caused by unequal expansion and contraction - 
 than anything else. This is due to lack of uniformity of distribution of heat or the 
 sudden heating or cooling of the surface or part of the porcelain body. Different 
 degrees of heat produce dift'erent degrees of expansion and the surface or some portion 
 of the body of porcelain heating or cooling faster than the interior or some other 
 portion of the mass; and porcelain being a low conductor of heat, an unequal stress 
 is set up that is relieved only by fracture. 
 
CASTING, WITH SPECIAL REFERENCE TO PORCELAIN 219 
 
 Fracture is also caused by permitting molten solder in soldering or molten gold 
 in casting to flow around an edge, and in the contraction of cooling a grip is set up 
 that will break any porcelain made. Such fracture is due to improper waxing up 
 of the case for either soldering or casting. 
 
 It is also claimed that a metal pin in a porcelain body — such as the post of a 
 Logan crown — will expand faster than the porcelain, and thus cause fracture. That 
 claim sounds plausible, but is little more than sound, for a degree of heat that would 
 expand the metal sufficiently to do that would have already fractured the porcelain 
 by suddenly expanding the surface. Also where there is a post baked into a tooth 
 heat will be conducted into the center of the mass by the metal as well as being ab- 
 sorbed by the surface, and the distribution will be more uniform than if the post were 
 not present. If the heat were applied to the post directly and conducted to the 
 interior of the porcelain while the surface received a much lower heat, then the 
 expansion of the post and the layer of porcelain surrounding it would be faster than 
 that of the surface' and fracture would result. But to do that would recjuire con- 
 siderable trouble to bring about something nobody wants. 
 
 The fractures indirectly caused by borax are brought about by a union of borax 
 with the porcelain, causing it to lose its elasticity and become more brittle, as is the 
 case when gold is alloyed with some base metals. This loss of elasticity renders it 
 less capable of resisting the stress of expansion and contraction, and a slighter in- 
 equality of temperature will cause a fracture, than if the integrity of the porcelain 
 had not been impaired. 
 
 An inlay or all-gold casting of any nature may be successfully cast in a com- 
 paratively cool or a cold mold, as is proven by castings of iron and brass foundries. 
 But to cast upon porcelain without fracture the mold must of necessity be brought 
 to such a temperature that the porcelain bodies contained will be subjected to no 
 undue strain of unequal expansion by sudden contact with molten gold of much 
 higher temperature. 
 
 The investment ring is readily raised to a red heat; but investment material is 
 a low conductor of heat, and several minutes will elapse before the heat is distributed 
 throughout the mass. So, unless sufficient time is given, the porcelain in the mold 
 will be several hundred degrees cooler than the surface, and the molten gold forced 
 into the mold will fracture the porcelain just as cold glass fractures by sudden con- 
 tact with hot water. Get the porcelain in the mold thoroughly hot and you may cast 
 all the gold on it necessary for any denture ever put in the mouth, and the tiniest 
 facing will never be checked if properly waxed and invested. No flux is needed for 
 any cast, and borax when fused is very sticky and, uniting with the investment, inter- 
 feres with the entrance of gold into the sprue-hole. 
 
 Logan crown joints may be fitted as accurately as the margins of inlays, and thus 
 they become the most perfect crown restorations known to the profession, and may be 
 perfectly adapted to roots far below the gum line all around or at any point. Molar 
 stumps in the same condition ma}' be easily and beautifully restored the same way 
 by placing a pin in each canal and using plate teeth with pins baked in or diatoric 
 teeth. No fear need be had in casting into diatoric teeth, for the molten gold enters 
 the recess in them at its maximum expansion, and the contraction upon cooling makes 
 the post thus formed slightly smaller. 
 
 Removable pin crowns, such as Justi's, the Davis, etc., have no lateral openings, 
 as have the diatoric teeth; consequently' the molten gold will not enter and com- 
 pletely fill the recess provided for the pin because there is no avenue of escape for 
 
220 PRACTICAL MANUAL OF DENTAL CASTING 
 
 the air caught in the i^eccss. It, therefore, is better to remove the crown from the 
 wax before investing, and the porcelain need not be subjected to heat at all, but may 
 be cemented on the post after the gold that perfects the adaptation to the root has 
 been cast onto the post. 
 
 To use such crowns for dummies, clip the post off to the desired length, insert 
 in crowns, wax crowns in position, chill with ice water, slip crowns off posts, cast, 
 and cement crowns in place, and you have a most beautiful and practical case. 
 Crowns and dummies thus constructed are far less apt to break away than those 
 backed and soldered, for they are supported by perfect contact of gold at every point, 
 while a backing touches only here and there, and their retention depends almost 
 entirely upon the strength of the pins baked into the porcelain. And if one should 
 break, grind up and cement another on the prj^t left standing. 
 
 Pure gold should be used for inlays and 22-karat gold for everything else. In 
 casting inlays and shell crowns do not waste gold by casting them unnecessarily 
 thick. Hollow inlays are easily made, a much stronger retention is secured, and a 
 greater thickness of cement protects the pulp from thermal irritation. There is on 
 the market a device consisting of a hollow metal bulb, with small extending point, 
 through which a hole extends back to a tube to which is attached a rubber tube with 
 a mouthpiece. This end is taken in the mouth, the metal bulb is heated, and when 
 the hot point is touched to the surface of the wax model to be hollowed out, the 
 melted wax is instantly sucked back into the bulb, leaving edges as clear-cut as if 
 cut with a knife. The same thing may be done with an ordinary hot-air syringe or 
 chip blower having a bulbous nozzle. Solder to the nozzle the shank of a hypo- 
 dermic needle, having bored out the needle with a small drill. Connect the rubber 
 bulb to the metal tube with six or eight inches of rubber tubing, so the bulb may be 
 worked with one hand and the metal point directed steadily with the other. Mount 
 the wax model of the inlay on the sprue-pin fixed in a base to hold it steady, and then 
 with the point heated suck out any kind of undercut or hollow you desire. 
 
 This is but a small part of the merits and possibilities of the process of casting 
 as applied in dentistry; but too much time cannot be taken up with one writing. 
 
 — Dental Headlisht. 
 
REMARKS ON CASTING 
 
 By Robert N. LeCron, D. D. S., London, England 
 
 At the present time the cast plate seems to hold the center of the dental stage 
 amongst the; recent reproductions in metal, especially in England, where ijlate-work 
 nourishes to a greater extent than in any other country. Hence, those interested 
 in the exi)erimcntal stages of casting arc called n])on to answer many qucsli'tus as 
 (() the reasons for this, that, and the other regarding the results, possibilities, and 
 (he future of the cast-plate. 
 
 riiis branch of the work still being in its infancy renders some of the cjuestions 
 asked practically impossible to answer. We can only hope to arrive at definite 
 conclusions after a long series of experiments along practical lines, not alone from a 
 demonstrator's viewpoint but from conclusions based upon practical work in the 
 mouth of the dentist himself. Casting under pressure is ancient, yet it is a new idea 
 as applied to dentistry' today, and like all new things, is being worked to death, 
 just as porcelain work was misapplied in many instances; but like all things abused it 
 shall find a place amongst the branches of dentistry according to its merits as tested 
 by time. 
 
 The echo from all sides seems to be complaint as to the casting of thin gold plate. 
 It seems strange that so much stress should be laid upon the idea of a thin plate. 
 True, in the case of gold the thin denture is that which is desired and necessary, but, 
 nevertheless, it is curious that a thin gold plate, full or otherwise, should be the 
 source of so much trouble and comment, when some of the following details are taken 
 into consideration. From a casting standpoint only, the thicker the plate or the 
 more bulky the object to be cast, the greater the air space or cushion within the mold 
 to get rid of, after the wax or object has been burned out and the greater the amount 
 of metal necessary for the casting of same, and in like proportion the greater the 
 surplus metal required, consequently a greater heat must be used to melt this bulk 
 of metal and a still greater care to see that it is not only molten but in a proper con- 
 dition to flow into a mold. Then too, the greater the mass of molten metal over the 
 gate openings,* especially with gold or any of the heavier metals, the greater the 
 liability for that metal to sag or e\'en flow into the gate or gates before the pressure 
 is applied. Hence, the thinner the plate or the object to be cast the less the dif- 
 ficulties and the easier and more certain the result. 
 
 One of the most important factors in casting, regardless of the methotl used, 
 whether it be by gravitation or by pressure, is the getting rid of the air from within 
 the mold quickly and with the least possible resistance to the escape of that air, as 
 the molten metal enters and spreads to the remote parts or crevices of the mold. 
 
 While watching various demonstrations on casting, I have heard the question 
 asked and have been asked many times myself: What becomes of the air cushion 
 within the mold? Demonstrators must have an answer ready at all times, otherwise 
 they are liable to find themseh'es in an awkward position. Some insist that upon 
 heating up the case the air within the mold becomes rarified — and so it does; but not 
 to the extent of producing a vacuum, as sometimes implied, or anything approaching 
 
 The words gate, lead and runner in this article are used to express what is generally termed sprue 
 
222 PRACTICAL MANUAL OF DENTAL CASTING 
 
 such a highly rarefied condition. If it were possible to produce a vacuum — the 
 casting apparatus with the method of melting the metal in a crucible directly over 
 the gate openings would be practically useless. If such was a fact, upon melting 
 the metal upon a flat crucible-like surface of one of these highly heated cases, one 
 would naturally expect bits of the molten metal to be drawn into the mold as parts 
 melt and fall away from the yet unsettled portion, instead of melting gradually and 
 remaining in a liquid mass over the gate openings, until a positive pressure be applied. 
 
 Perhaps the above is the cause of some failures, where the case is heated until 
 it glows red from within through the gate openings. In speaking of extensive castings 
 where fifteen or more hundredweights of heavy metal are used, capillary contraction 
 is not sufficient to cause the molten mass to globuJate to any great extent, far less 
 overcome the suction from beneath, caused by the supposed vacuum within the 
 mold. 
 
 The air surrounding tlic molten mass becomes more and more rarefied, it is true, 
 as the intensity of the heat increases for melting purposes, and no doubt, theoreticalh' 
 overcomes and counteracts the vacuum within the mold, which space has had a greater 
 or less opportunity to cool while melting the ingot. (At least, this is one explanation 
 set forth.) If the above be a correct theory, the question then arises: Why, if the 
 mold be ventilated, is the molten metal more liable to sag into the gate openings, or 
 to actually flow into the mold without the application of pressure providing the mold 
 be sufficiently vented than in a case where mechanical vents are lacking? 
 
 For instance, before Doctor Taggart conceived the idea of casting as it is now 
 applied to dentistr>', some were casting into matrices. Shortly after this method 
 was given out, but not known in detail to the profession generally, many more were 
 experimenting along these lines of gravitation. 
 
 This method is known to all and simply consists of a mold with a vent leading 
 from the same to the outside of the investment, and a large gate opening into the 
 same. The metal, instead of being melted over the gate opening, was melted in a 
 crucible to one side with a lead or avenue to the large orifice of the gate opening. 
 As soon as the molten metal was in the proper condition to flow, the case was tipped 
 to one side allowing the metal to flow into the gate or runner and gravitate thence 
 into the heated mold. This method was applied only to small castings, and the 
 success of the same depended not only upon the thorough heating up of the case, a 
 large gate and plenty of metal, but also upon the vent opening to allow for the escape 
 of the air from within the mold. These cases were heated extremely hot, yet the 
 rarefication of the air within the mold thus brought about was not sufficient to secure 
 a perfect result in any instance, unless there was a vent from the mold to the outside. 
 One realizes quite readily how difficult it is to pour water or any liquid into a bottle 
 or closed flask where the air contained within must escape from the same aperture 
 through which the liquid is being poured. If, however, there be another outlet to 
 the atmospheric pressure within the flask the procedure is quite simple. 
 
 With castings such as poured by the working jewelers in cuttle-fish bone, and 
 those on a larger scale in foundries into molding sand, some of the important details 
 are as follows: Sufficient vents, a large runner, depending on the size and the complica- 
 tion of the casting in hand, and sufficient bulk of metal in a thoroi:ghly molten condition 
 to flow. At least, these were the prime factors most impressed upon my mind while 
 taking a course in a molding shop. All necessary on account of the mold being cold, 
 and the flow of the metal depending alone upon its own weight and surplus behind 
 
REMARKS ON CASTING 22;j 
 
 called the runner and sulhcicnt access to all parts of the mold to enalile the liquid 
 mass to spread quickly co all parts without interference from the air within. 
 
 Though a mold be well vented, if it be filled from the top the casting is liable to 
 be full of blow holes. In such cases dense castings may be obtained by giving an 
 extra length at the top of the mold away from the runner — the unsound portion being 
 thus formed in this extra length and cut away afterwards as the deadhead. 
 
 In casting a metal under pressure, the conditions are ditTerent and allow and 
 necessitate certain changes or deviations from the old method: however, it is always 
 well to bear in mind the law of gravitation and the details go\erning cheoplastic art. 
 
 On account of the metal being melted in a crucible, directh' over the opening or 
 lead into the mold, instead of pouring the liquid mass into a runner — this lead or gate 
 must be much smaller in diameter. If too large, the metal is liable to sag into the 
 same; if too small, the construction offers too great an obstruction to the flow of the 
 metal. With small castings, it is remarkable what a small gate opening the metal 
 may be forced through. 
 
 I have been trying to determine by a series of experiments, not }et completed, 
 the size, length and number of the gate wires necessary for the various castings in the 
 different metals; for each metal allows of a different treatment. With aluminum or 
 any of the lighter metals, most any size gate seems to answer the purpose; but as 
 there is no tendenc>- for these mecals to sag, a very large- gate will be found most 
 useful. The heavier metals in large castings require more care in the selection of 
 the gate wires; with such metals as tin and Watt's metal that melt at a low temper- 
 ature and remain liquefied for some considerable time, smaller gates may be used 
 than with the same case in gold that solidifies quickly. 
 
 If attempting a large casting in gold through one lead, there i? an inlluence 
 towards using a large gate wire, thereby rendering a failure more possible. Hence I 
 prefer to use two or more smaller gates leading to various parts of the mold to 
 minimize uncertainties. Casting a metal into a mold in a bulk is quite different from 
 that of casting the same quantity where it must spread for some distance from its 
 entrance into the mold. 
 
 In short, with the data to hand. I can but sa>' that I adhere to the following 
 details as nearly as possible until I satisfy myself more fully on this subject, /. e., 
 the heavier and the greater the bulk of the metal to be used with the exception of 
 tin and Watt's metal and similar metals and the thinner the object to be cast, the 
 smaller the gate openings and the greater the number of the same radiating from a 
 common center to various parts of the mold, and last, but by no means least, the 
 flatter the crucible or surface upon which the metal is to be melted. 
 
 Certain stress has been laid upon the subject of ventilation, yet a few more 
 words may lie added. There are m.any methods whereby this important procedure 
 may be accomplished. With small work, the porosity of the investment should be 
 quite suiificient. By the word small I not onK' imply inla\s, but crowns, bridges — 
 in fact, any design within the radius of two and a half inches. Larger objects may 
 be cast relying upon the same escape for the internal gases, in which cases the pro- 
 cedure of investing is an important detail, /. f., to be certain that the distance 
 through the investment from the top down to the mold is greater than the distance 
 from the mold down through the base, and where the metal must flow for some con- 
 siderable di.stance from the entrance cf the gate openings into the molds, to be careful 
 that these remote parts be quilr near to the base, so that as the metal enters and 
 spreads to those distant parts the air contined therein is forced thnuiL;h but a \ery 
 
224 PRACTICAL MANUAL OF DENTAL CASTING 
 
 thill layer ot inxestincnt to the outside of the cup; and the pressure from abo\e has 
 little chance of driving air through the thick investment over these parts before the 
 metal spreads to the same. 
 
 The air within the mold is either taken up by the investment similar to a sponge, 
 absorbing water, and like the sponge, it has a limited capacity, after which the re- 
 maining air must be driven through the investment to the outside or remain within 
 with the liability of causing blow holes by reacting upon the molten mass or defects 
 by not allowing the metal to spread. Any air driven out into the investment is 
 driven there under pressure; hence to further assist the escape of internal air or gases 
 I find it quite convenient to perforate the lower strata of investment through into 
 the mold with a fine, smooth broach before the wax or object is burned out. To 
 leave these mechanical vents open is liable to cause trouble if a heavy metal is to be 
 used; by rubbing some of the surplus investment over the base these holes or vents 
 may be temporarily stopped to hold the air cushion within, which in turn prevents, 
 along with other details, the metal from sagging into the open gate while being melted. 
 As soon as the pressure is applied for casting, these slight stoppings blow out, leaving 
 open rents through which the air may pass with the least possible resistance. 
 
 If there is any one detail in the mechanical process more important than another, 
 I should say that it is the melting of the metal. There is a certain condition of a 
 molten metal at which that respective metal will cast to the best advantage, and it 
 is not the boiling point. Any ordinary blow-pipe may be used that will, with the 
 proper manipulation, melt the metal quickly with a strong blue flame; in no instance 
 should a large smoky flame be used, for it only tends to oxidize and spoil the working 
 of the metal. Once the metal has been melted, one should not be too anxious to 
 cast, but should employ a small soft flame for a short time upon the already molten 
 mass until certain it is in the proper condition to flow into a mold. Take, for in- 
 stance, in the ordinary casting of zinc and lead for dies, etc., considerable care is 
 taken that the molten metal is not bubbling from being too hot and, on the other 
 hand, not sluggish from being too cold before pouring. If the metal be in the proper 
 condition one need not be in a great hurry to apply the pressure, for it will remain in 
 a liquid form some considerable time. 
 
 In conclusion, simply because the molten metal is to be driven by force into the 
 mold is not sufficient reason for being careless about the melting of the metal, even 
 in such simple castings as inlays, and yet expect an apparatus of any description to 
 duplicate perfect castings under such adverse conditions. — Dental Brief. 
 
PLATE CASTING BY THE VACUUM PROCESS 
 By W. L. Harpel, D. D. S., and F. L. Olds, D. D. S. 
 
 The first step in plate casting is to obtain a perfect plaster impression. All 
 relief-work necessary must be done on the impression, because the model cannot 
 be altered after pouring. 
 
 When the impression has set, apply a coat of Separlac, filling the pores of the 
 plaster, thus producing a smooth, glossy surface. Twenty to thirty minutes should 
 be allowed for drying the varnish. 
 
 All air must be expelled from the impression. To do this, i)!acc in water and 
 allow it to remain there until Ijubbling stops. 
 
 Models should be made from Imperial Investment Compound. There may be 
 other good compounds obtainable, but we know of none that compares at all with 
 Imperial for the making of models. The cost is so trifling that it is not worth while 
 to experiment. 
 
 The proper mixture is one part water to four parts investment. See that the 
 mix is thorough. Chemical action must take place within every atom of the in- 
 vestment. Do not beat or stir the mixture violently; spatulate it gently but con- 
 tinue until a thorough amalgamation has taken place. Otherwise bubbles will 
 form and the cast cannot be satisfactorv. 
 
 Plate 1 — The Finished Model 
 
 Plate 2 — Model \Va-xed 
 
 After the model has been poured and allowed to harden, requiring ten to fifteen 
 minutes, separate and trim as thin as can safely be handled, allowing flanges to pro- 
 ject as shown in illustration. The smooth surface of the model must be maintained; 
 therefore do not attempt to make any alterations on the model. A little Canton 
 graphite rubbed over the casting surface of the model with the finger will add to its 
 smoothness, anci insure a bright, polished surface on the cast. 
 
 Thin base-plate wax is to be adapted to the model, allowing it to cover it a little 
 higher than the plate is to be v.'hen cast. In trimming the sheet, be guided by the 
 height of the plate, both buccally and labially. Use a wax that does not become 
 quite brittle when cold. A light-colored translucent wax is to be preferred. Do not 
 use highly-colored or dirty wax, as it is sure to leave a residue when removed by heat; 
 likely to cause holes in the plate. 
 
226 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Wax must be carefully sealed to model all around with a hot spatula; otherwise 
 investment may work in between the wax and model. 
 
 Lay a ruler, with beveled edge, the long way of a sheet of wax, and with a warm 
 knife held against the edge of the ruler at an angle of 45 , cut strips of the wax }/^- 
 inch wide and full length of the sheet. 
 
 Warm the strips of wax slightly, and lay around buccal and labial edges of wax 
 base where the pencil mark shows through base plate, to form outer rim. Turn 
 around heel of plate over tuberosities and around palatal portion to form inner rim. 
 These strips of wax will meet at center of plate. Seal strips down with a hot spatula 
 and a little extra wax. 
 
 The beveled edges of the strips must be placed next to the surface upon which 
 attachment is to be made. See that the wax rims thus formed present perfect 
 under-cuts. Cut small lugs of wax and place them where they will give best at- 
 tachment, or the metal may be spurred or picked for vulcanite attachment after 
 casting. 
 
 Cover wooden-sprue-block with a thin coating of wax to facilitate removal from 
 the investment; cut four strips of base plate wax, one-half to three-quarter inches 
 long and three-eighths wide and attach to wooden sprue-block in such position that 
 one will connect with the wax base plate at each of the tuberosities and the others 
 palatally to form gates. This wax should be of same thickness as that used for 
 the plate. 
 
 To determine the distance of sprue-block from wax model, place model on flat 
 outside surface of flask and within one-half inch of bottom or small end, and attach 
 wax strips so that sprue-block will be even with top of flask. 
 
 The gates should not exceed three-eighths inch in width, as , if wider, the metal 
 may be carried down by gravity before the valve is opened, spoiling the cast. 
 
 Place model with wax base and sprue-block in water and let it soak until all 
 bubbling has stopped. 
 
 We are now ready to invest the case for casting; but, before going further, we 
 must be sure that we are ready to proceed with the operation at once. The case 
 must be heated up and cast as soon as invested; otherwise checks are sure to occur, 
 and the cast will be spoiled. 
 
 Standard Investment Compound (not Imperial) is recommended for all casting 
 operations (not for models). It is finely ground, yet porous, withstands the action 
 of heat better than others and reproduces the finest lines with the utmost nicety. 
 
 When ready to invest, not before, mix a sufficient quantity of Standard Invest- 
 ment to a consistency that will just admit of its being poured from the bowl. Paint 
 the model thoroughly with the mixed investment, using a fine brush, being careful 
 to fill all undercuts. Fill the plate-flask three-quarters full of the investment, place 
 the model therein, and gently press to place. 
 
 The model should come to within one-half inch of the bottom of flask. 
 
 The flanges allowed to project at the sides near the labial end of the model will 
 prevent its going into the flask too far. 
 
 Be sure to get model as nearly into center of flask laterally as possible. 
 
 When thoroughly set and dry, which should be in 15 to 20 minutes, slightly 
 concave the investment at the bottom or small end, of flask, place in absolutely clean 
 boiling water and let it remain until the wax is softened; a little gentle pressure with 
 an old rubber file or long instrument, on the sprue-block will cause it to float out. 
 Remove case from water at once and l)rcak waay any frail pieces of investment so 
 
PLATE CASTING BY THE VACUUM PROCESS 227 
 
 that they may not drop into the sprue holes (openings formed by wax gates). The 
 remaining wax can easily be washed out by holding the case slightly oblique and pour- 
 ing a small stream of absolutely clean boiling water into upper gate. Any tin 
 receptacle with a small hole punched through the bottom at one of its edges makes a 
 good vessel for the purpose. Care must be taken to exclude all dirt from the mold. 
 To burn out the wax place point of knife under edge of sprue-block and carefully 
 lift from place; then heat on bracket of adjustable stand very slowly at first, keeping 
 the flame low until steam no longer rises from the case. Then increase the flame 
 until it is giving all the heat po.ssible, holding it there until the wax has entirely 
 burned out and the case is heated as directed above. 
 
 Plate 3 — Model Mounted on Sprue-former, Showing Gates 
 
 If the boiling-out process is used, immediately after boiling place over a slmv 
 fire, allowing it to remain until all steaming has stopped, occasionally turning the 
 fiask. Test for moisture with mirror. When no moisture appears place directly 
 over a spreading flame. Cover with an inverted pan to insure even distribution of 
 heat, occasionally turning flask until it is a dull red all over and stays so. Do not 
 permit flame to strike directly upon the investment at any time. 
 
 When the case has been carried to this point put an ingot of Aerdentalloy or 
 double refined Aluminum in the meltmg crucible and set above flame with Economy 
 Heat Cap over it. Now invert flask and let flame come in contact with crucible 
 surface while metal is melting. 
 
 The overheating of the metal will ruin it, and the melting process must be care- 
 fully watched. A blowpipe flame should not be used directly on the metal. 
 
 When metal has fused (fused, remember, not burned), pump up the vacuum to 
 twenty or twenty-five inches; take case from fire and place on bed-plate of appliance, 
 first examining bottom of flask and bed-plate to see that there is nothing to prevent 
 perfect contact. Turn valve to see if contact is perfect. 
 
 When contact is perfect, the hand of the indicator will fall \qv\ slowly; but if 
 contact is not perfect the hand will fall rapidly. 
 
 Grasp the crucible, containing the molten metal, with a pair of I'nixersal 
 Laboratory Pliers and quickly jiour the metal into the funnel-shaped depression in 
 the top of flask (called crucible). When I he nulai is ail in and the s[)rue holes co\ered 
 turn the \'alve. 
 
228 PRACTICAL MANUAL OF DENTAL CASTING 
 
 The pouring of the metal and opening of valve should be made almost one con- 
 tinuous movement as a very little delay at this point will spoil the case. Never 
 turn the valve until all the metal is in the crucible, but do not delay. Prompt, 
 decisive action is necessary. 
 
 The metal chills very rapidly, and both case and flask should be nearly the 
 temperature of fused metal when pouring. 
 
 Remember, sharp holes in the plates indicate heating too fast and thereby ex- 
 ploding pieces off the investment on the inside. 
 
 Round holes indicate that the case was not hot enough before casting, or at the 
 time the cast was made. Holes along edges indicate that too little metal has been 
 used. 
 
 Let the case stand before opening until it has cooled enough to be picked up by 
 the naked hand. Remove case from flask. Cut off sprues, preferably with saw. 
 finish with files, stones, emerj' paper, felt cones and pumice, and polish with any good 
 material. Clean and oil the flask on the bottom to prevent rusting while flask is not 
 in use. 
 
 We do not recommend the casting of teeth direct to metal plates, although it 
 can be done. The vulcanite attachment is preferred as safer and better. 
 
 Some Important Suggestions * 
 
 Be sure to test the appliance for leakage before attempting to cast. To do this, 
 pump up the gauge to fifteen or twenty inches; put flask or ring on bed-plate and 
 firmly closing the larger opening with the palm of the hand, open the valve; the 
 hand of the indicator will remain stationary, provided contact is perfect and there is 
 no leak. Otherwise the hand will fall, rapidly or slowly, depending upon the nature 
 of the leak. If there is a leak, find it and remedy it before going further. 
 
 If the flask has become oxidized on bottom and that is the point of leakage 
 (which usually is the case) mix some fine carborundum powder with oil on a piece 
 of plate glass (not ordinary glass because its flatness cannot be depended upon), 
 and grind bottom surface of flask on glass until perfectly true and clean. Also oil 
 contact surface of bed-plate. 
 
 Do not let your rings or bed-plate become rusty or dirty; oil them immediately 
 after using and cover bed-plate when not in use. Bear in mind that neglect in keep- 
 ing clean the bed-plate and neglecting to keep the rings flat on the bottom mean 
 failure. 
 
 If the leakage is not found to be as indicated above, place a little saliva or soap 
 suds around the different joints between tank and attachments and around air cocks; 
 then pump up, place the palm of hand over bed-plate and turn the valve. The 
 leakage will cause the saliva or suds to be drawn in. If the leak is at a joint, unscrew 
 the attachment, mix a little dental cement and place it on both connections and 
 screw up. 
 
 Should there be leakage of air about an air cock, remove the thumb control by 
 taking out the screw on rear end and removing cap-washer, when a light tap will 
 loosen it. (Jive all contact surfaces a light coating of special vah'e wax, supplied 
 with the outfit. .Additional quantit\' can be procured from the manufacturer (price, 
 lU cents per box). 
 
 Should it still be difficult to maintain a vacuum in the cylinder, the trouble may 
 be caused by the collection of dust and wax about the pump valve. Remove pump 
 and valve; clean all parts, valve, valve-seat and hexagon cone tip with gasoline and 
 
PLATE CASTING BY THE VACUUM PROCESS 220 
 
 replace. If this docs not rcnicd}- the difficult)-, procure a new \al\e from the man- 
 ufacturer (price, 10 cents); rcmo^■e the pump, take off the nut on its inner end, and 
 the valve will be found in the nut. The nut is of soft metal and must be handled 
 carefully. Use a true wrench, with sharp square jaws. 
 
 Replace the valve removed with the new one, being careful to insert so that the 
 cork in the valve will impinge against the cone-point of the nut when air is exhausted 
 from the Appliance. Smear a very little paint or white lead on the thread of the 
 nut, and screw to place. 
 
 The pump plunger should be oiled occasionally through the holes through which 
 the air escapes. 
 
 Slight leakage of air into the tank is liable to occur owing to the tremendous air 
 pressure if an attempt is made to hold the vacuum too long. It is practicallv 
 impossible to hold a vacuum for any great length of time. The vacuum should be 
 produced, therefore, just previous to melting. 
 
 If the indicator of the gauge does not register correctly, remove the rim, the 
 glass front and the face of the indicator. This allows free access to the simple 
 inner mechanism of the gauge. In re-assembling, put indicator or hand of gauge 
 over its pivot with the point just below the pin to the left. Press the indicator 
 firmly to place, then spring the end over the pin and replace glass and rim. If 
 necessary to remove the gauge, first take out the glass to prevent breakage; then 
 place a light wooden strip across the face of the gauge, resting on the rim, and another 
 across the back. These strips should project beyond the periphery of the gauge 
 sufficiently to give leverage and act as a wrench. Then unscrew the gauge from 
 its seat. 
 
INLAY CASTING BY THE VACUUM PROCESS 
 
 By L. W. Strycker, New York 
 
 Prepare cavity so that wax will draw from it without dragging or becoming 
 distorted. If properly prepared, the wax will draw out in one way only. 
 
 Freely moisten cavity, or use a very little alboline, to prevent wax model from 
 adhering to walls. Be careful to get none of the lubricant on point of wax to which 
 sprue is to be attached, nor upon the sprue wire. 
 
 Soften Standard Inlay Wax and force into cavity, being sure that it goes firmly 
 to every portion; if on the occlusal obtain bite. 
 
 Chill wax in cavity, burnish to margins, carve to conform to occlusion, restore 
 contour, allowing wax to extend slightly over margin of cavity, and remove model 
 with a sharp instrument. 
 
 Select a sprue wire of a size adapted to size of model, being careful not to use 
 one too large; a small one should be used for small models. 
 
 None but perfectly clean wax should be used and the wax pattern should be so 
 carefully made and handled, and the surface so well polished, that it is without a flaw. 
 
 Inlays, either of gold or acolite, should be cast as soon as wax pattern is made, 
 while the wax is still warm from the mouth. 
 
 Slightly heat point of sprue wire and attach it to wax model, adjusting wire in 
 crucible-former so that the bottom of the model will be no nearer than one-eighth of 
 an inch to the bottom of casting ring, when the top of sprue-former is even with 
 the top of ring. 
 
 The investing material should be carefully chosen. It must conform to the 
 pattern perfectly, so as to produce a perfect casting, exactly reproducing the original. 
 
 It should be an investment that will not crack or check, but will harden under 
 heat, so that when the molten metal enters, it will not break down the frail walls 
 of investment. An investment that above all expands under heat, taking up as 
 much as possible the natural shrinkage of metal when cast. 
 
 Standard Investment Compound has been specially prepared for the vacuum 
 process of casting. There are other good investments for other methods, but none 
 is so good for the vacuum process. 
 
 Mix Standard Investment Compound with tepid water to consistency of thick 
 cream and fill ring. 
 
 With a fine sable brush (the finer the better), carefully cover model and wire 
 with the compound, working carefully into every angle and cranny and carefully 
 blowing the investment off once or twice to prevent bubbles forming next to wax 
 model; bubbles fill with metal when cast, causing rough casting; failure to avoid 
 these bubbles, no matter how small, will prevent the fitting of the inlay. Paint on 
 enough investment to cover the model thoroughly, and then place crucible-former 
 with pattern attached on any fiat surface, pattern upward; then set ring over 
 this with small end up. Pour investment in from one side, until ring is filled. 
 Then take firm hold of ring with one hand, being careful not to move it laterally, 
 and slightly raise it, to allow the air bubbles to escape around the bottom of ring, 
 but do not jar it by tai)])ing on the side, lx>cause wax has an affinity for air bubbles 
 
INLAY CASTING BY THE VACUUM PROCESS 
 
 231 
 
 suspended in an investment and tapping will cause them to attach themselves to 
 the wax pattern and will not release. F"or acolite, it has been found better to invest 
 a little higher in ring than for gold. Fig. 1 illustrates a good investment position for 
 acolite and Fig. 2 for gold. 
 
 F'igure 1 also illustrates an incorrectly formed crucible. Flame from blowpipe 
 cannot reach the metal and it will not fuse properly. The form should be shallow 
 and wide as shown in Fig. 2. This allows the flame to envelop the metal and it will 
 fuse properly 
 
 Fis. 1. 
 
 Fig. 2. 
 
 When investment is set (which, if properly mixed, takes about eight minutes in 
 small ring and twelve minutes in large ring), concave the investment slightly at 
 bottom or small end of ring. Avoid a smooth surface, as the air will not draw through 
 a smooth surface as readily as a porous one, and be sure that the bottom of ring is 
 perfectly clean. 
 
 With knife or small instrument gently lift out the crucible-former; the sprue 
 wire will remain in the investment; heat the sprue wire sufficiently over a Bunsen 
 Burner to remove it from investment. In removing sprue wire, hold ring upside 
 down, thereby avoiding the danger of small particles of investment failing into 
 sprue hole. (See Fig. 3.) 
 
 Fig. ,3 
 
232 PRACTICAL MANUAL OF DENTAL CASTING 
 
 Now oil the bottom, or small end, of ring only (with alboline), then ring is ready 
 for heating. Place it, on its side, on the heating stand, over Bunsen Burner, so that 
 heat from flame strikes about the center. Heat very slowly at first, as too rapid 
 heating generates steam within the investment, causing it to explode and break away 
 small particles of investment, thereby endangering the casting. As soon as heat is 
 turned on ring, cover with heat cap and gradually increase heat, turning ring around 
 from time to time, until it has become a dull red all over and the investment is also 
 red hot through and through. This last may be determined by holding the ring with 
 a pair of Universal Laboratory Pliers and looking down into the sprue hole, where it 
 will be seen that it is a dull red at the bottom. Be sure the wax is thoroughly burned 
 out; a frequent cause of failure lies here. 
 
 When case is about heated, pump up vacuum until the gauge registers fifteen 
 inches. See that seat for ring is perfectly clean. When case is hot place ring in 
 position on bed-plate, with small end down. 
 
 Before fusing the metal test the contact of ring to bed-plate, by turning valve 
 on and ofi quickly. If the contact is perfect, the indicator will fall very slowly, if 
 at all. When the contact is not perfect, it is usually made perfect by turning the ring 
 on its base. 
 
 If scrap gold has been kept free from platinum, silver and base metals, it may 
 be used for inlays. It has the advantage of retaining its shape better than pure gold. 
 Before using, however, always melt scrap gold into a nugget, on a charcoal block. 
 Never melt scraps on the investment as small particles may melt before the mass 
 and drop into sprue entrance and clog it. 
 
 If scrap is used it should first be boiled in 50 per cent. Nitric Acid, to remove any 
 base metals that may be present, washed and placed upon a charcoal block and 
 melted. While the mass is in a molten condition it should be sprinkled with Am- 
 monium Chloride (Sal Ammoniac). This should be repeated until the gold ripples 
 like water. This may be remelted in a carbon crucible and cast into ingots for 
 future use or used as it is. 
 
 Very little flux should be used in melting gold, as there is danger of its flowing 
 into the sprue and closing the opening into the mold, preventing a perfect cast, even 
 if the gold goes down at all. Borax should never be used for a flux. It has a ten- 
 dency to seek the bottom of the molten metal and will cover up the sprue hole. 
 
 A nugget of sufficient size should be used not only to cast the inlay but the sprue 
 also, and still have a sufficient quantity left in the crucible to keep air from entering 
 the opening. Holes along the sprue indicate that too little metal has been used. 
 
 Fuse metal, if gold, reducing every particle to a thoroughly liquid state. Then 
 turn the valve and keep the flame on the gold until the indicator shows a drop of 
 five or six points. It is not sufficient merely to melt the gold. A very little Ideal 
 Flux, sprinkled carefully on top of the melting mass, will facilitate melting and flow- 
 ing. No flux need be used in melting 24-karat gold. 
 
 A good blowpipe is very Essential, one that has perfect combustion. The quicker 
 the gold is liquefied while the investment is hot, the better the results and the more 
 perfect the reproduction of the wax model. A natural gas flame is generally not 
 hot enough. 
 
 It is extremely liNporlaiil that gold \>v thoroughly iuaud and in perfect condition. 
 
 After the inlay is cast it should be washed thoroughly to remove all investment 
 attached, then placed in Hydrofluoric Acid which will remove any fused silex. The 
 sprue should then be carefully cut off and the cavity surface examined minutely for 
 
INLAY CASTING BY THE VACUUM PROCESS 233 
 
 any small bubbles of gold that may be attaelud. If (he imesdneiU is painted on 
 very carefully at first there will be little trouble in this respect. 
 
 If there is any difificulty in getting the inlay seated in the cavit>', an excellent 
 method is to heat the inlay slightly and apply a very slight layer of mercury to the 
 surface. This will unite with the gold and upon evaporating away with increased 
 heat the gold will be left with a frosted surface. If the inlay is now placed in the 
 cavity any point that may rub against the walls will become burnished and can be 
 cut away. When the inlay goes to place perfectly, the surface should again be etched, 
 for the better adhesion of the cement. 
 
 All inaccessible surfaces of the inlay should be trimmed and polished before 
 setting. However, if it is possible to reach the margin with a burnisher, it should be 
 left slightly flush to permit a thorough burnishing before the cement sets, after which 
 the margins should be finished and polished the same as for a gold filling. 
 
 To cast Acolite follow directions for casting gold, except that it must be borne 
 in mind that Acolite fuses at a much lower point than gold, and is in the proper 
 condition for casting the moment it becomes fluidic. Do not continue playing the 
 flame upon the metal beyond that point. Heat continued be>ond the fluid point 
 will burn and oxydize the metal. 
 
 Acolite should be cast in molds at much lower temperature than gold. After 
 the wax has been burned out, set the case off the fire and allow it to cool until it can 
 be comfortably handled with the naked hand. Then cast. 
 
 Place the ring on bed-plate, drop the acolite into the formed crucible, apply 
 just enough heat to fuse the metal, and open the valve. For casting acolite the 
 vacuum should never be pumped up higher than 10 inches. Faulty margins are 
 due to lack of pressure or loss of air. 
 
 Perfectly clean wax, water, gold and other materials must be used. 
 
 Investments must be properly mixed and applied. 
 
 The wax must be thoroughly burned out. 
 
 Aerdentalloy, Aluminum and Acolite must not be overheated. 
 
 A sprue wire adapted to the size of model must be used. 
 
 The investing material must be adapted to the vacuum process. 
 
 More metal than is required for the case must be used. If holes appear in 
 casting near or alongside the sprue, more gold m^ist be used; or add 2^(, platinum 
 wire rolled thin, and fed into the boiling gold. 
 
 Good clean gold in nugget form must be used and thoroughly fused. 
 
 Cases must be promptly cast after the investment has set. 
 
 If inlays come out black and rough, case has not been sufificiently heated. Get 
 it hot through and through, so that a dull red spot can be seen when lookingintothe 
 sprue hole. Carbon deposit left by wax must be burned out. Dark spots are 
 caused by gases given off by combustion of wax. If burned out clean before casting, 
 the inlay will be clean. 
 
REINFORCING PRINCIPLE OF MESH IN WAX PATTERN WORK 
 
 By A. W. Tatham, D.D.S., Detroit, Mich. 
 
 Detailed description of any particular form of crown is properly preceded by 
 a few general considerations relative to this subject, so rapidly gaining in the attention 
 of our profession generally. The principle of reinforcing wax patterns for castings 
 is applied most practically to root bases for any form of crown, whether it is anterior 
 all-porcelain with inlay setting or a posterior bicuspid or molar used either as a 
 single restoration or abutment for bridge. Some forms of crowns lend themselves 
 more easily than others to this method. Let us consider first the anterior inlay 
 setting. A perfectly non-impinging coping is, beyond all dispute, the thing to be 
 attained, and may be by the following technique: 
 
 Prepare the root end, making a well-defined bevel, and upon the root place a 
 small strip of mesh — push pin through and trim to approximately the proper size 
 of mesh to be used. 
 
 Now remove and run some hot wax upon the upper side of mesh, replace upon 
 the root, and with a piece of soft red rubber such as is used for pencil eraser, force 
 mesh and wax down upon the root. Special emphasis is laid here upon the use of 
 the rubber, because nothing else will so easily and surely enable you to force the 
 waxed mesh well home and slightly over the edges. 
 
 Take this pattern off, turning the inside upward, and you may find that a little 
 more wax is required. If so, run in just a surface, or, with a hot round burnisher, 
 remelt the whole inside. While this is warm, re-adapt thoroughly to the root, 
 using rubber again. The slight margins may now be very easily and accurately 
 brought to place by the use of a slightly warm flat burnisher. Trim this pattern, 
 as you would a band, to suit the case in hand. Toward the labial side nearly all of 
 the coping may be trimmed off for esthetic reasons. Replace the pattern as many 
 times as is necessary to bring margins to place. To warm the pattern for these 
 re adaptations, drop it into warm water, or move it to and fro over a flame until 
 uniformly warmed through. 
 
 The next step is to place the crown upon the top of the root base pattern, and 
 this is easily accomplished by warming the upper portion of the pattern while it is 
 on the root, with a hot air chip blower. If wax is insut!:cient, run a little more over 
 the surface. The tooth should be slightly warmed to prevent too sudden chilling 
 of the wax. Thus it is readily seen a very thin wax impression, with a slightly 
 
REINFORCIXG PRIXCIPLE OF MESH EX WAX PA TTERX WORK 2:i.-, 
 
 turnover edge for coping, may be manipulated with surprising ease and accuracy 
 This coping will fit when cast and give uniform results. 
 
 The foregoing technique is employed where a pronounced band or margin is 
 required. The following technique will be found ven.- efficient where no extensive 
 margin or turnover edge is essential. 
 
 Another technique especially useful for all anterior teeth where only a thin joint 
 is required is to trim the mesh tooth-wise, press a piece of mesh with thumb upon the 
 tooth, prick hole for head of pin, push pin with flange into tooth, having flange this 
 side of mesh, tack with a little warm wax and trim the mesh around the crown 
 properly. 
 
 The next step is to run enough hot wax around pin and pattern and j'ou arc 
 ready to press crown and pattern upon the root. 
 
 In this technique the method is simple and positive, the mesh acting as a guide 
 for extreme thinness of anterior part of pattern and prevents all spreading and 
 splitting of pattern. 
 
 Note — Hollow sprues are ver\" advantageous in root base patterns. 
 
 It must be quite apparent to anyone having made these patterns, without 
 reinforcement, the number of difficulties encountered. One of the most annoying 
 troubles in forcing down this pattern is the splitting or spreading of the wa.x — to say 
 nothing of the lack of slight turnover, which is wholly absent or inaccurate. This, 
 to my mind, is one of the most important uses of the mesh, as the forming of an ac- 
 curate and esthetic adjustment of the anterior porcelain crown ever>- operator is 
 compelled to face. This operation is rendered practical and easy by the aid of the 
 mesh. 
 
 CROWN" BRIDGE .\BUT.MEXT 
 
 Let us consider a t>pe of crown for crown bridge abutment. The waxed mesh 
 base is practically the same as for the base described above, except that the pin is 
 bent over at a right angle or a thin disc cf gold or silver tacked to pin, with solder 
 mesh ahvays placed upper side of disc, making removal of pattern ea.s>- — also that 
 some roots rccjuirc a definite band. Make this band hy extending the \\axcd mesh 
 
236 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 and trim as you would in forming a metal band. Note at this point a most impor- 
 tant feature of gold mesh, i. e., it does not buckle; it is woven, therefore pliable, 
 giving in all directions, and may be placed upon the root and extended some dis- 
 tance as a band without the annoyances encountered in continuous metal. 
 
 Select a tooth of the Goslee type, or Steele's Facing, all-porcelain type, since 
 these give the Y-shape slant or space necessary for adjustment and surface for 
 soldering the dummy teeth in for bridgework. Here is a means for adjusting the 
 tooth directly in the mouth in most cases without casting the root base separately — 
 eliminating running of models, etc. The mesh is placed upon the tooth, hot wax 
 
 run upon the mesh; pressed to place quickly; taken ofif the tooth; re-trimmed and 
 re-adapted in the same manner as a root base impression. These two patterns are 
 now ready to be attached. The point is that the mesh upon the tooth, the tip end 
 for attaching, may be heated and attached at any angle or removed as often as is 
 necessary, and when finally articulated, the porcelain tooth, by reason of the mesh 
 reinforcing pattern, may be easily taken from the pattern without distortion. 
 
 Furthermore, the mesh-wax patterns are unlike those with a continuous metal 
 backing, because they can be re-shaped or changed readily. The enmeshing qualities, 
 ever present in adjustment, render it possible to achieve through casting, truly 
 splendid results. Only men who will not see or who prefer the old way, just because 
 it is old, fail to see in this progressive method that which gives to casting its most 
 desirable feature. The molar crown can be just as easily manipulated as a bicuspid. 
 In the process of adjustment it may become necessary, in articulating a bicuspid. 
 
 to place a warm little ball of beeswax for a cushion while obtaining adjustment. 
 This ball need not be taken out, but finished right over with the inlay wax. The 
 beeswax cushion, remaining soft a long time, facilitates articulation, which otherwise 
 would be dilificult of accomplishment. 
 
 Should it become necessary to cast the base separately and then take an im- 
 pression and run models, an accurate pattern for base and crown can be easily formed 
 in a short time, and the two patterns can be cast in the same mold. The two castings 
 may then be waxed in place upon the articulation and soldered together. Care must 
 be taken to make the root base pattern very thin. There is to be noted here a very 
 important point in favor of the mesh. A hot spatula may be run over, where pat- 
 tern is in position on root, taking off the wax or shaping right down to the mesh 
 
REINFORCING PRINCIPLE OF MESH IN WAX PA TIERN WORK 2:37 
 
 il.sclf, and ihe impression on the under side will remain unharmed. This palLern is 
 left \er> thin so that there will be room for adjusting the tooth coping to the root 
 base coping when they are set upon the articulator for articulation. It is assumed 
 that a tooth will be selected and approximately fitted before attempting to form 
 any pattern. 
 
 Much might be said concerning the modifications of these two types, but believe 
 that the anterior all-porcelain type for anterior and the saddle shape all-porcelain 
 typefor bridge abutments are the most generally used, being esthetic and economical. 
 The selection of teeth for bridge abutments and dummies for bridgework would be 
 seriously hampered for casting without a proper facing type of tooth suited to wax 
 pattern work. The usual type of fixed pin facing tooth is not very satisfactory for 
 casting. The new Dimelow facing presents a form of facing that is best suited to 
 wax pattern work. The staple pins draw with the wax mesh pattern, giving a 
 re]jlaceable facing The staple pins enter into the holes of porcelain facing at an 
 
 angle, giving strength and permitting the tipping of the cutting edge of the facing. 
 This facing has a distinct advantage in short bite and forming of wax mesh dummies. 
 It will be readily seen that the reinforcing principle may be applied to any form 
 of root of any size, in any position, anterior or posterior — without having always to 
 change technique or to encounter other difificulties. 
 
 ALLOYED EDGES 
 It is quite well established that pure gold, properly treated, casts best. For a 
 thin margin or band, the one objection to pure gold is that, being soft, it lacks the 
 proper tenacity for polishing and burnishing to advantage. The mesh is 22k, and 
 when the pure gold is cast into it the edges or margins become an allo>", giving the 
 pure gold just the required quality for this part of the casting. Thus, one ma\- cast 
 with pure gold and while in the mold form an alloy where it is most needed. 
 
 CERVICAL TWO-THIRDS 
 
 There are very few operators who are not willing to admit thai the approximai 
 space at this point offers some difficulties and inaccuracies in forming the wax 
 pattern. The application of reinforcing the wax pattern at this [wint is so simple 
 and eflectivc that only a brief description of the technique is recjuired. Manii>uiate 
 
238 
 
 PRACTICAL MANUAL OF DENTAL CASTING 
 
 between teeth as you would a piece of silk tape; enter the mesh into the pattern with 
 warm, thin spatula; remove, trim surplus mesh, leaving margin; over this flow a 
 little wax; return to cavity and burnish margin with warm spatula. By this 
 principle you are always certain that the cervical two-thirds is correct. 
 
 Just a word in regard to compound inlays or shallow wax inlay patterns. These 
 patterns often become distorted in drawing, and is not noticed until too late. Many 
 times the adding of wax to an edge or margin of these types of inlays is quite difficult. 
 When the general reinforcement or framework of mesh is employed, these difficulties 
 are obviated. Technique is similar to root base. Another feature of no minor 
 
 importance is the "'Mesh Bite Crown." A band is made and adjusted in the usual 
 way. Attach a mesh cover at top of the band. Tack mesh with solder at two 
 points. A slight amount of wax is placed in the mesh and a bite is taken. Easy 
 and accurate adjustment is quickly made, requiring no carving inside and taking a 
 minimum amount of gold for occlusion. The crown is cast. The outer edges of 
 the mesh prevent the edges of the occlusion from shrinking in over the band. Union 
 is perfect. 
 
 In the case of the gold crown, where the bite is very short and the crown part of 
 tooth is gone, generally requiring a solid construction, and where a porcelain crown 
 cannot be used — make band in usual way; cap with mesh. Insert pins through mesh 
 
 into root channel. The bite is now taken and crown is ready for casting. This 
 gives a strong attachment since the casting usually has at least two pins, and these 
 may be tied together by placing a small amount of wax between the pins close up to 
 the top on the under side. In the casting, gold takes the place of the wax and makes 
 a very strong connection of the pins to the crown. 
 
 CONTROL OK SHRINKAGE AND WARPAGE 
 
 How, it is often asked, can the mesh exert any restraining power over the cooling 
 metal? Let the most conservative but impartial operator make a reasonable 
 number of tests, casting both with and without the mesh, taking the same care that 
 he docs in his ordinary practice in casting, and he will find results more uniform with 
 
REINFORCING PRINCIPLE OF MESH IN WAX PA TTERN WORK 239 
 
 mesh than without. Without mesh, under ideal conditions, with a perfect tech- 
 nique, and the expenditure of much time, observing carefully all the details of 
 casting, one can obtain good results. Now, the majority of busy practitioners who 
 are doing casting, appreciate some of the difficulties, especially in root base work, 
 when they get down to every-day practice and have an open mind and a welcome for 
 a simple and scientific principle that lightens, expedites and assures good results. 
 
 Here is the result of a test made: 
 
 A wax pattern with several thicknesses of mesh, also one without mesh, were cast 
 at the same time, under the same and very favorable conditions, and submitted for 
 analysis to an expert. It was found that the specific gravity of the casting containing 
 
 the mesh was considerably less than that without mesh, indicating that the interstices 
 contained air, and which would have a tendency to throw the contraction from the 
 surface which the mesh immediately underlies. Another theory is that the casting 
 cools quickest around the mesh, inasmuch as tests have proven that the mesh does 
 not melt upon being surrounded by the molten gold, and which would have a tend- 
 ency to minimize the contraction in the surface which the mesh immediately under- 
 lies — the adaptation surface. 
 
 Exhaustive tests have also proven that the mesh does not hamper the casting. 
 Care, however, should be taken to bring the gold to liquid state. Use equivalent 
 to ten pounds' pressure. 
 
 Note. A certain amount of change of shape of wax paltern is due to the wax. The mesh 
 acts as a stiffener and prevents this trouble. 
 
 COMBINATION FILLINGS OF CAST GOLD AND PORCELAIN OR 
 SILICATE CEMENTS 
 
 By Dr. C. H. Neill, Fairmont, W. Va. 
 
 This is a method of using cast gold inlaws in conjunction with hnv-fusing porce- 
 lain and silicate cements. 
 
 In the large approximal inciscjr cavities in the anterior teeth, to replace the 
 ordinary contoured filling or contoured inhu', I prepare the wax model in the usual 
 manner and remove the labial aspect of it; prepare in the labial aspect a box-shaped 
 cavity, cast inlay, cement into position, and start a new operation on the labial 
 cavity prepared in the inlay. That gives us the same strength of a gold inlay without 
 the labial aspect of gold. If artificial enamel is used the incisal edges can be well 
 protected. If low-fusing porcelain is u.sed as a veneer there need be no gold showing 
 at all. 
 
THE TECHNIQUE OF CASTING 
 
 USING STEELE'S INTERCHANGEABLE TEETH AND BACKINGS 
 By Dr. C. E. Talbert, Columbus, Ohio. 
 
 I shall not advance any theories or suppositions in the paper which follows, but 
 will give merely a plain statement of facts which have been proven by several years 
 of experiment and daily practice. 
 
 The technique of casting a crown or bridge, using Steele's interchangeable 
 teeth and backings, is practically the same, up to the point of investing, as that of a 
 crown or bridge that is to be completed by soldering, the only difference being that 
 the backings and other parts to be cast upon must he fluxed in the manner as heroin- 
 after described, and that the waxing must be more carefully done and the piece 
 carved just as it is desired to have it when finished. 
 
 Let us take, for example, an incisor Richmond. You are supposed to have the 
 coping and pin in place, either in the mouth or upon a model. It is imperative that 
 
 Fig. 1 
 
 the pin be either of platinum or iridio-platinum, as a base metal, such as platinoid, 
 will often become disintegrated and weakened. Select the proper tooth and grind 
 to place, preserving the bevel of the ridge-lap, or increasing it a little if necessary, 
 so that when the grinding is completed it will touch the coping at its extreme labio- 
 cervical point only, leaving a V-shaped space between the two. Now place the tooth 
 upon the backing and trim the latter to the tooth, closely on the sides, but leaving 
 it a little longer than the tooth at the incisal edge. Next grind the ridge-lap end of 
 the backing to the tooth, giving it the same bevel. Remove the backing and, 
 grasping it with a pair of soldering pliers, hold it so that the beveled end will be level, 
 and place a tiny speck of 20k solder on the corner of the backing farthest from you, 
 as in Fig. 1. Hold in the flame until the solder sweats down, but remove before it 
 flows. Next take a piece of 34-gauge pure gold or a piece of platinum foil slightly 
 wider than the backing and long enough to balance on the end thereof, with enough 
 material projecting over the ridge-lap to cover the end of the tooth when the latter 
 is in place (Fig. 2). Have this piece perfectly flat so that when it is laid upon the 
 end of the backing it will have a three-point contact, viz: the little globule of solder, 
 the opposite corner of the backing, and the end of the post. Carry carefully to the 
 flame and hold steadily until a slight movement of the piece indicates that the solder 
 has flowed and the piece settled to place. Now put the tooth on the backing and 
 be sure that it goes easily to place without forcing, not only at this time but after all 
 subsequent operations of soldering or casting. If there is found to be any obstruc- 
 tion, remove it carefully before proceeding further. Now trim around the cervical 
 
THE TECHNIQUE OF CASTING 
 
 :ii 
 
 edge, but leave that portion of the Hap that ovi'Haijs the l)aekiiig, which is to l)e 
 burnished down closely, as is also that part which covers the end of the tooth (Pig. '^). 
 Drop the piece, while hot, in pickle and leave for a few minutes. It will then be 
 ready for the flux. The flux to be used — and it is the only one that can be used 
 successfully — is a saturated solution of boracic acid in grain alcohol. This is also a 
 most satisfactory flux for all small soldering operations. 
 
 To prepare a stock solution, fill a bottle about one-fourth full of boracic acid and 
 fill up with alcohol, shake a few minutes and allow to settle, using only the clear 
 
 Fig. 2 
 
 liquid. If you have a considerable excess of the powder, the stock can be kept up 
 by occasionally refilling with alcohol. The best way to apply the flux is from an 
 office preparation bottle with a small camel's hair brush, or the piece can be dipped 
 bodily into it. 
 
 Take the piece to be fluxed in a pair of soldering pliers and apply the solution. 
 Ignite the alcohol from the flame and allow it to burn ofT. Then hold the piece in 
 the flame a moment — until you see the deposit fuse, but do not allow it to approach 
 a red heat. Allow it to cool spontaneously and you will find the surface uniformly 
 covered with a thin film of flux that can be handled without displacement and which. 
 
 Mg. -i 
 
 in the subsequent operation of casting, will absolutely prevent oxidization of the 
 surface to be cast upon. No care need be taken to keep the flux from the face of 
 the backing, nor is any antiflux or other stop-out necessary, as in the case of a 
 soldered piece, as the investment used, if properly applied, answers ever>' purpose. 
 We are now ready to proceed with waxing up the case. Unlike the casting of 
 inlays, the wax to be used is of little importance except as regards its tenacity in 
 holding the parts together and the facility with which it may be carxed. A good, 
 sticky- wax is best to unite the parts so that they may be removed from the mouth or 
 the model. The operation may then be completed with pink baseplate wax. wiiich 
 carves very nicelv, or with anv of the casting waxes on the market. Flow on enouuh 
 
242 PRACTICAL MANUAL OF DENTAL CASTING 
 
 wax to give the desired contour and build the incisal edge to a thickness about equal 
 to No. 20-gauge plate. Trim the wax flush with the end of the backing, which, as 
 previously mentioned, must be slightly longer than the tooth. This is with the 
 object of protecting the porcelain when the piece has been finished and finally 
 mounted, which object may be still farther advanced by grinding the porcelain 
 very thin, thus precluding the possibility of contact with the occluding tooth. After 
 grinding, the porcelain may be repolished with gloss sticks or other polishing material. 
 
 Of course, the entire Richmond or bridge dummy, including the backing and 
 post, may be cast in one piece if desired, in which case the method of procedure would 
 be first to grind the tooth into place, either in the mouth or on the model, and then 
 remove and cither thoroughly wet or oil the slot and back of the tooth. Then flow 
 on, to the proper thickness, some good casting wax, being sure to have the slot well 
 hiled. After chilling it may be waxed to place, carved as desired, the tooth removed 
 and the case proceeded with as hereafter described. There are some serious objec- 
 tions to this method, however, the chief of which are, first, the difficulty of removing 
 and replacing the tooth without distorting the post or backing, and the fact that 
 after casting the post will fit the slot so closely as to preclude proper cementation 
 when the case is completed. Furthermore, no matter how carefully the piece may be 
 invested, there is almost certain to be some minute globules of gold cast along the 
 post or upon the ridge-lap or backing, which would cause considerable trouble in 
 removing. 
 
 Some of these objections may be removed by using the posts for casting which 
 are supplied by the manufacturers, but the danger still remains that the post may be 
 gotten out of alignment or otherwise displaced or the backing distorted. In view of 
 these considerations, I strongly recommend the use of the backings, as supplied by 
 the makers, in the manner already described. 
 
 The investment of the piece is next in order, and the investment material, next 
 to the f.iix, is of the utmost importance. I shall not enter upon a discussion of the 
 qualities necessary to a good investment, but will give you the formula for, and the 
 method of preparing, that which I have selected as the best, after several years' 
 trial of most of those now offered by the dealers. It is composed of four parts by 
 weight of finely powdered silex and one part of French's in- pression plaster. These 
 ingredients must be thoroughly mixed by repeated siftings. I sift them twenty to 
 thirty times through a fine sieve and make up enough at one time to last several 
 months, as the longer the mixture is kept the better it is, provided it is stored in a 
 dry, warm place in isooden boxes, the wood tending to absorb any slight moisture it 
 may contain. Too much importance cannot be attached to the mixing and curing 
 of this investment material. 
 
 The operation of investing the piece is practically the same as that of investing 
 an inlay. Place the sprue wire so that it points directly into the V-shaped space 
 between the ridge-lap apron and the coping, and mount the piece on the crucible- 
 former. Mix a tolerably thick batter of investment and paint it onto the piece with 
 a very small stiff brush, working it well under the backing post and very carefully 
 excluding even the minutest air bubbles. After the piece is well covered, place the 
 casting ring on the base and proceed to pour the balance of the mix, being careful 
 to add but little at a time, and working it down around the sides of the flask with a 
 small cement spatula, and by holding the flask firmly down and tapping the sides 
 with the spatula handle. 
 
 The correct proportions of in\es1ment material and water for a pro[)cr mix, as 
 
THE TECHNIQUE OF CASTING 
 
 243 
 
 well as a sufficient amount to fill the ordinary inlay flask, are 12 dwts. of investment 
 and two teaspoonfuls of water. You double this quantity for a larger flask. Procure 
 a small tin ointment box, and after weighing this amount shake it well down level 
 and trim the box to the level of the material; you will then have a correct measure 
 for all subsequent mixes. 
 
 When the investment is set, which will be in about eight minutes, warm and 
 remove the crucible-former. Grasp the sprue wire with a pair of hot pliers, holding 
 it so for a few minutes that the heat may be transmitted to the wire, when it may be 
 easily withdrawn. Place the flask on its side on an inclined rack, about two inches 
 above the opening of a Bunsen burner, with the sprue opening at the lowest point — 
 that the melting wax may to a certain extent drain out. Have the flame turned as 
 low as possible. It should not be more than half an inch high, as shown in Fig. 4. 
 Keep at this point for twenty-five minutes, at the end of which time turn it up to 
 
 Fig. 4 
 
 Fig. 5 
 
 about an inch (Fig. 5). .\l the end (jf fi^•e minutes more turn up until the flame 
 barely touches the flask (Fig. 6), and after another five minutes turn on the full 
 flame (Fig. 7). After five minutes more it is ready for the cast. To summarize: 
 Twenty-five minutes for the first heat, five minutes for the second, five minutes for 
 the third, and five minutes for the fourth — forty minutes all told. Have the air and 
 gas so regulated in the burner that it will burn with a slightly yellow flame rather 
 than a noisy blue one. The flame during the last heat will then lap entirely around 
 the flask instead of splitting off at the sides. At the end of the time allotted for 
 the heating the flask should show slightly red, but the investment not at all, and it 
 must be removed from the fire and the cast made without allowing it to cool longer 
 than is necessary- while preparing to melt the gold. 
 
 The gold to be used in casting must necessarily be of considerable lower karat 
 than that which it is to be cast upon. It has generally been conceded that the solder 
 sold for use with ISk plate is good enough for a soldered bridge. At any rate, it is 
 the highest karat that can be safely used in casting upon 20k gold or platinum allo>- 
 backings. If you wish to use a finer gold you must have pure gold or pure platinum 
 backings. Before fusing the solder for making the cast it must first be melted into 
 a nugget upon a charcoal block, using plenty of borax and app!>ing only just sufticient 
 
244 PRACTICAL MANUAL OF DENTAL CASTING 
 
 heat to accomplish the purpose. Do not attempt to use less than four dwts. of 
 solder for casting a Richmond, and more in the same proportion for a bridge, as it is 
 important to have plenty of excess. Note carefully the sluggish action of the solder 
 under the blow-pipe so that you may be able to judge when fusing for the cast just 
 when the fusion is complete, as it will not dance and boil as a higher grade of gold 
 usually does. Also after casting, the pressure must be sustained a little longer 
 than is necessary when using a higher grade of gold. 
 
 The technique of casting a bridge does not differ materially from that of a crown, 
 except that provision must be made for easily removing it from the model and a 
 greater number of feeders supplied. 
 
 Before pouring the impression any shell crown must be partly filled with wax 
 and the posts of Richmond crowns partly covered so that by slightly warming they 
 may be readily removed and replaced after cleaning. The model must then be 
 slightly oiled between the abutments with liquid vaseline or other oil, and the case 
 proceeded with as in case of a soldered bridge. This, however, is one of the methods 
 often used in soldered work. 
 
 After the case is waxed and carved as it is desired to have it reproduced, there 
 is nothing more to do but to fix the sprues and proceed to invest the cast. 
 
 The feeders must be at least three in number — one wire placed about the center 
 and two feeders formed by little rolls of wax, one at either end of the bridge converg- 
 ing to the free end of the wire and waxed to it with a hot spatula. It may now be 
 mounted upon the base or crucible-former and proceeded with as previously 
 described. 
 
 In conclusion, I will recapitulate the more important considerations: 
 
 First — The method of fluxing, which has not to my knowledge been published 
 before, is absolutely essential to a perfect union between the metal cast and the metal 
 cast upon and will invariably produce that result. 
 
 Second — The investment must be one that will not shrink or check and one that 
 will spread with a brush like paint and fill in smoothly without bubbles. 
 
 Third — The case must not be overheated — the merest approach to redness of 
 the flask is permissible, but the gold within must not reach the red heat. This result 
 will be closely approximated by following the formula for heating as given, but by 
 experiment may be changed to suit any slight difference in the burner used. 
 
 Fourth — If solder is used in casting much caution must be used not to overheat 
 in fusing, but be sure it is fused and cast as soon as you are certain that it is. 
 
 If these four essential features are carefully observed there will be few, if any, 
 failures. 
 
HOLDING INLAYS WHILE POLISHING 
 
 By Dr. G. B. Speer, Los Angeles, Cal. 
 
 In the February number of the Summary, Dr. R. C. Brophv, of Chicago, gave 
 a description of Dr. Moore's vise for holding inlays while polishing. My way is as 
 follows: 
 
 Take a pair of Dr. W. Van Hook's (or other make) mouse tooth hemostatic 
 forceps, which can be gotten at any surgical supply house for $1.25. Snap them on 
 the inlay and you can hold it in any shape desired. Also, let your assistant turn a 
 stream of cold air on the inlay while grinding and it remains cool. The assistant 
 and cold air have been a great help to me at the chair by keeping the bur cool while 
 cleaning out cavities. 
 
 And while you are buying your hemostatic, also buy a five-pound can of sur- 
 geon's green soap and use same for moistening felt and brush wheels in polishing 
 plates. The remainder may be used for washing the hands. Once you have used 
 this soap you will never go back to any other. It is not only cheaper, but cleanses 
 and softens the hands much better. 
 
 How I make a sprue wire for holding and removing inlays: Take a German 
 silver wire and flatten the end with a hammer; now trim ofif the edges until the flat 
 part is only as wide as the thickness of the wire; now hold the wire in your pin vise, 
 catching close to the flat part, and with a pair of pliers twist the flat part to form a 
 screw, point the end with a file and you have a sprue wire that will hold. 
 
 Do not warm the wire, but insert by a pushing twist, thus screwing the sprue 
 into the impression. Blow a stream of cold air on the impression and your wire will 
 hold. 
 
 CAST BACKINGS AND CROWNS FOR STEELE'S FACINGS 
 
 By James B. Doyle, D.D.S., Grand Rapids, Mich. 
 
 First take the Steele facing, then a piece of platinum or pure gold, about 36- 
 gauge. Pinch it together and insert it in the groove, then take a small instrument 
 and burnish it to place so that it fits the groove perfectly, then take a piece of 22k 
 plate gold or platinum and cut it so it will readily pass into the root canal and the 
 groove of the facing. Remove and solder these two pieces together; after greasing 
 your facing with vaseline you are ready for your inlay wax. Mold it as well as 
 possible to the back of the facing and your root canal pin. Then after the wax is 
 properly warm you insert it in the root canal and press up firmly. Remove and 
 carve until you have the shape desired. Then remove your facing and you are 
 ready for casting. Now you have a perfect fit of your facing to your backing and a 
 perfect fit to your canal. 
 
 I cast all my backings for Steele's facings. You proceed in the same manner 
 except that you do not use a pin. There is a great advantage in making bridges 
 with Steele's facings and casting your backings. The reason so many facings break 
 is because you cannot get uniform thickness with solder. You will get a little more 
 solder in one place than another and it is liable to spring. That spring will be just 
 enough to crack your facing. And another thing, you cannot always get your 
 backings to fit so that the stress of mastication will come upon it. By casting vour 
 backings you overcome these difficulties. 
 
CAST CUSP CROWN 
 
 By C. E. White, Indianapolis, Ind. 
 
 Prepare root in proper manner, cut a piece of 22k gold large enough to make the 
 band, wide enough to include cusps, fit the band to root and trim to occlusion. 
 Contour the band with pliers to form the cusps. Place warm inlay wax, or better 
 still, Alexander's gold, inside the band, condense same or trim and carve (if wax) 
 to occlusion. If wax, invest and cast; if Alexander's gold, place solder on cusp of 
 crown, place over Bunsen burner, burn out wax and sweat solder in the gold. Polish 
 the crown and cement it on at the same sitting. 
 
 AN INLAY FOR COMPOUND CAVITY INVOLVING INCISAL 
 V^ITHOUT STEP 
 
 By H. C. Dean, D.D.S., Columbus, Ohio. 
 
 It is often desired to place a gold inlay involving the approximal side and incisal 
 edge, without sacrificing the sound structure of the tooth to make a step. This may 
 be done by placing an iridio-platinum post near the incisal after the inlay has been 
 completed. Inlay should have a wide, deep groove carved in the approximal surface 
 extending from near the incisal to the gingival. This should be done in the wax 
 model. This groove is to pass over the iridio-platinum post, when the inlay may be 
 set from the incisal without interference from an approximating tooth. There may 
 be an extension of this iridio-platinum post for additional retention in the groove of 
 the inlay. Since the inlay model is completed before the incisal retention post is 
 provided, there is absolutely no interference with the removal of the model. The 
 retention post fits loosely in the tooth and in the inlay until cemented. Post and 
 inlay are both set with same mix of cement. 
 
 HOW TO CAST AN INLAY WHEN YOUR CASTING MACHINE IS 
 OUT OF ORDER 
 
 By Dr. W. J. Boydston, Fairmont, W. Va. 
 
 The casting machine consists of a tube alxnit eight inches long and about an 
 inch and a half in diameter, filled with plaster of Paris to within about two inches of 
 the top. Fill this vacancy with putty or moldine. Over this place wet tissue paper, 
 about six to eight thicknesses. Heat your investment and proceed as in other cast- 
 ing, exerting about six to eight pounds of hand pressure. 
 
 Then this other crown is a porcelain-faced cap crown, by use of Steele facing with 
 cast back. You grind your tooth the same as for a gold crown; then grind buccal 
 surface the same as for Richmond crown. Then cut face of band out; swage your 
 cusp and catch it on the lingual edge of band with solder; readjust to tooth; allow 
 patient to bite and adjust articulation. Then grind Steele facing to approximately 
 fit portion of band ground away; cut back the facing with vaseline; press it into 
 warm casting wax and while still warm place on face of band. Press into place, 
 chili, remove, trim, and build up contour with wax. Remove facing, insert screw 
 in the buccal incisor edge of wax; invest, and proceed as in other casting. After 
 casting flow solder around cast and band. Grind down and finish and place in facing. 
 
TABLE OF CONTENTS 
 
 The Cast Inlay: 
 
 Early Attempts at Inlay Casting C. V. Vignes 12 
 
 Tcchnic of a Cast Gold Inlay A. F. Miller 13 
 
 Cavity Preparation for Cast Gold Inlay Thomas P. Hinman. 37 
 
 Shaping Wax Model for Gold Inlays C. E. Abbott 38 
 
 The Cement Line in Inlays Clarence J. Grieves. 39 
 
 Some Practical Points on Inlays L. E Custer 68 
 
 Separate Base for Gold Inlay F. R. Henshaw 67 
 
 The Cast Gold Inlay James W. Lyons ... 81 
 
 Anchor for Fillings and Inlays W. H. Pelton 105 
 
 Method of Producing Perfect Margins C. Kabell 116 
 
 Nuggets of Gold — Inlays O. E. Lanphear. ... 117 
 
 Limitations and Uses of the Gold Ink}- H. M. Semans 120 
 
 The Gold Inlay J. V. Conzett 122 
 
 Hollow Cast Inlays W. S. Payson 125 
 
 To Hollow Out Wax Model for Inlay S. T. Neill 125 
 
 Casting Wax T. C. Trigger 136 
 
 The Impression Method for Inlay Work Henry W. Gillett. . . 137 
 
 The Cast Gold Inlay C. G. Myers 149 
 
 Porcelain and Gold Inlays A. W. Starbuck. . . . 163 
 
 Amalgam Base for Gold Inlay Steele F. Gilmore ... 192 
 
 The Working Model for Inlay Practice H. W. Arthur 205 
 
 Conductivity of Cast Inlays S. H. Guilford 208 
 
 Some More Progression R. C. Brophy 213 
 
 Inlay Casting by the Vacuum Process L. W. Strycker . . . 230 
 
 Holding Inlays While Polishing G. B. Speer 245 
 
 Combination Fillings of Cast Gold and Porcelain on 
 
 Silicate Cement C. H. Neill 239 
 
 Inlay for Compound Cavity H. C. Dean 246 
 
 How to Cast an Inlay When Casting Machine is Out 
 
 of Order W. J. Boydston 246 
 
 Crown and Bkidgk Work: 
 
 Porcelain Crown with Cast Gold Base W. .\. Sanderson . . 14 
 
 Telescopic Crown for Bridge Work E. L. Kanaga 22 
 
 Casting Process as Applied to Crown and Bridge Work . Hart J. Goslce 28 
 
 Restoring Teeth for Crown and Bridge Work C. Jensen 67 
 
 Hollow Wax Dummies of Bicuspids and Molars T. C. Hutchinson.. . 69 
 
 Cast Gold Crown C. E. Mcerhoff 80 
 
 Cast Jointed Logan Crown C.J. Burris 80 
 
 Casting Pins for Crowns W. A. Stewart 102 
 
 Casting Backings for All-Porcelain Fronts D. Haight 102 
 
 Anterior Bridge Abutments for Splinting George C. McCann. 104 
 
 Cast Posts for Steele's Facings George H. Walker. . 106 
 
 Methods of Casting in Crown and Bridge Work W. G. Crantlall . . 107 
 
 An Ideal Bicuspid or Molar Crown George S. Schlegel. . Ill 
 
 Cast Abutments for Bridges W. W. McCall 112 
 
 Pin and Coping for Porcelain Crown Paul J. l>o\cns 115 
 
TABLE OF CONTENTS— Continued 
 
 Crown and Bridge Work J. H. Laudry 123 
 
 An Anterior Cast Bridge E. Cunningham .... 125 
 
 Casting Large Bridges W. H. Hayden 126 
 
 A Richmond Crown Without Solder T. C. Hutchinson. . . 127 
 
 To Overcome Weakness of Cast Gold Bridge W. J. Montgomery. 136 
 
 A Combination Cast Crown O. H. Simpson 155 
 
 Restoration by All-Porcelain Bridge and Bridges upon 
 
 Cast Bases J- M. Thompson . . . 157 
 
 Subgingival and Canal Restoration in Crown Work.. .Edward C. Mills, . . 161 
 
 Casting on Porcelain W. C. Gillespie 217 
 
 Cast Backings and Crowns for Steele's Facings James B. Bayle 245 
 
 Reinforcing Principle of Mesh in Wax Pattern Work. .A. W. Gatham 234 
 
 The Technique of Casting C. E. Talbert 240 
 
 Cast Cusp Crown C. E. White 246 
 
 Root Restorations: 
 
 Restoring Bicuspid Roots Auber Peebles 18 
 
 Restoration of Fractured Root J. Maurice Crosby. . 64 
 
 Restoration of Broken- Down Roots with Acolite James B. Lester. . . . 103 
 
 Restoration of Roots of Bicuspids and Molars A. W. McCullough.. 160 
 
 Cast Metal Plates: 
 
 Preparing Inlay Wax for Base Plate Newton W. Hiatt. . . 68 
 
 The Cast Aluminum Plate Robert Se^'mour. . . . 133 
 
 Collodion as a Separating Medium B. L. Worthley 136 
 
 Cowbell Method of Casting Plates D. D. Campbell 197 
 
 Cast Aluminum Plates George H. Wilson. . . 200 
 
 To Obtain a Smooth, Dense Surface on Casts F. L. Olds 215 
 
 Plate Casting by the Vacuum Process W. L. Harpel and 
 
 F. L. Olds 225 
 
 Origin and Progress of Dental Casting: 
 
 Ancient Origin of Dental Casting L. W. Stryckcr 5 
 
 Experience and Experiments in Casting. J- R- Osborne 65 
 
 Latest Developments in the Cast Gold Process Albert L. LeGro. ... 71 
 
 Casting; A Retrospect J- G. Lane 91 
 
 The Scope of Casting in Dentistry R. C. Brophy 113 
 
 Gleanings from the Field of Experience: 
 
 Investing to Avoid Shrinkage and Distortion C. J. Clark 15 
 
 Expansion and Contraction of Gold in Casting C. J. Clark 19 
 
 Air Vents in Casting D. D. Smith 68 
 
 A Soldering Device T. B. MaGill 90 
 
 Casting Gold on Porcelain E. Cunningham .... 122 
 
 The Cast Clasp W. B. Caldwell. .116-132 
 
 Places Where the Casting Process Has Been Found 
 
 Useful E. T. Tinker 193 
 
 Cast Gold Splints for Pyorrhea J. G. Lane 196 
 
 Some Pha.ses of the Casting Process C. S. Van Horn .... 202 
 
 Reproduction of Flowers, Etc., by Casting T. C. Hutchinson.. . 210 
 
 Remarks on Casting Robert N. LcCron. . 221 
 
ANOTHER VALUABLE BOOK 
 
 Interstitial Gingivitis 
 
 and 
 
 Pyorrhoea Alveolaris 
 
 By EUGENE S. TALBOT, M. S., D. D. S., M. D., LL. D. 
 
 Late Professor of Stomatology, Woman's Medical School, Northwestern 
 University; Late Lecturer on Stomatology, Rush Medical College, University of 
 Chicago; Fellow of The Chicago Academy of Medicine; Fellowship Member of the 
 New York State Dental Society, 1908; Secretary of Section on Stomatology of the 
 American Medical Association; Vice-President American Medical Association, 1905; 
 Member VII International Medical Congress, 1881, London; Honorary' President X 
 International Medical Congress, 1890, Berlin; Honorary President XII International 
 Medical Congress, 1897, Moscow; Corresponding Member Budapest Royal Society 
 of Physicians; Honorary President International Association of Stomatology, 1907, 
 Paris; Member First French Congress of Stomatology, 1907, Paris; Honorary 
 Secretary Pan-American Medical Congress, 1901, Havana; Honorary Member 
 Odontologischen Gesellschaft, Berlin; Honorary Member Association Generale des 
 Dentistes de France, Paris; Honorary Member Sociedad Odontological Espanola, 
 Madrid; Corresponding Member Dansk-Tandlaegeforening, 1901; Honorary 
 Member Stomatology Society of Hungary; Corresponding Member of the Italian 
 Stomatological Federation, 1910; Member Chicago Academy of Sciences; Member 
 American Association for the Advancement of Science; Charter Member American 
 Institute of Criminal Law and Criminology; Member of the Authors' Club, London. 
 Author of the following books: "The Irregularities of the Teeth and Their Treat- 
 ment;" "Chart of Typical Forms of Constitutional Irregularities of the Teeth;" 
 "The Etiology of Osseous Deformities of the Head, Face, Jaws and Teeth;" "De- 
 generacy: Its Signs, Causes and Results;" "Developmental Pathology: A Study in 
 Degenerative Evolution," Etc., Etc. 
 
 PARTIAL CONTENTS 
 
 Transitory Structures:: The Jaws and Alveolar Process; The Alveolar Process 
 Under the Microscope; The Gums, Periosteum, Mucous and Peridental Membranes 
 Under the Microscope; Inorganic Salts and Interstitial Gingivitis; Theories of 
 Interstitial Gingivitis; Degenerate Acid and Interstitial Gingivitis; Heredity and 
 Environment in Interstitial Gingivitis; Degenerate Tissues in Interstitial Gingivitis; 
 Bacteriologic Researches in Interstitial Gingivitis; Interstitial Gingivitis; Researches 
 on Animals in Interstitial Gingivitis; Researches on Human in Interstitial Gingivitis; 
 Researches on Human in Pericementis; Local Causes of Interstitial Gingivitis; Consti- 
 tutional Causes of Interstitial Gingivitis; Climate Influences in Interstitial Gingivitis; 
 Scurvy in Interstitial Gingivitis; Toxins Producing Trophic Changes; Autointoxica- 
 tion in Interstitial Gingivitis; Urinary Signs of Autointoxication; Arteriosclerosis, 
 Endareritis Obliterans and Nerve End Degeneration; Absorption of the Alveolar 
 Process and Calcic Deposits upon the Roots of the Teeth; Pyorrhea Alveolaris; 
 Constitutional Effects of Pyorrhea x^lveolaris; Treatment. 
 
 See reviews and opinions of this book on next page. 
 
 335 Pages : CLOTH $4.40 : 102 Illustrations 
 Published by The Ransom & Randolph Co., Toledo, Ohio 
 
Dr. James Truman, in an exhaustive review of more than six pages, in The Dental 
 Brief {or July, 1913, says: 
 
 A new work from the pen of Dr. Talbot is an event not to be passed as a mere 
 trifle on the great ocean of professional literature, but as a pronounced advance in 
 scientific knowledge. It seems only yesterday that a work from this indefatigable 
 investigator and writer was published, that the present writer regarded then as the 
 author's masterpiece, but before the ink is scarcely dry in this comes this volume on 
 interstitial gingivitis, the last, it is presumed, that will appear in book form from the 
 author's pen. 
 
 Dr. Talbot's work is always, to the inquiring student, a mine of facts. He does 
 not deal in theories, and the worker in his mine must be prepared with pick and 
 shovel to delve with him deeply in the strata of undiscovered things. 
 
 This work is beyond question the only thorough exposition of this pathological 
 condition familiar to the reviewer, either in Europe or America. 
 
 That there is no specific germ capable of producing this disease is abundantly 
 shown, as the work proceeds, and the researches of Galippe have not been confirmed, 
 either by the author or those associated with him. Dr. Theodore Chapin Beebe* 
 in a valuable article on" Pyorrhea Alveolaris and Treatment by the Opsonic Method," 
 says our vaccines are standardized at staphylococci 3^ c.c. equalling 500 million, 
 pneumococci ]/> c.c. equalling 100 million. These are mentioned as being the two 
 most common bacteria found in inflammatory conditions of the gums. 
 
 Chapter IX is taken up with the question of uric acid, which so largely dom- 
 inated the dental profession at one period, especially by Peirce, Rhein and others. 
 The judgment of the former was based on several experiments conducted at the 
 Drexel Institute, Philadelphia. The author claims that these were too limited in 
 number to be regarded as conclusive. He, the author, had had altogether "nine 
 hundred and fifty cases, and only a fourth per cent, showed uric acid * * * j^ 
 It is safe to say that six per cent, was the actual per cent, of uric acid." 
 
 In the chapter on "Heredity and Environment," the author sums up his con- 
 clusions in a few words, "Interstitial gingivitis and pyorrhea alveolaris are not 
 inherited." 
 
 Chapter XVII is one every dentist should carefully study. It is devoted to 
 "Local Causes of Interstitial Gingivitis." If there was nothing more than this 
 sentence in it, it should cause the average operator to think before deciding to operate 
 on a patient. " In a word, whatever irritates the gum margin, peridental membrane, 
 or alveolar process, is likely to produce inflammation which later becomes chronic." 
 Nothing more suggestive could be framed in words. The author might have ex- 
 tended this chapter in the direction of warnings, and while he covers much, there is 
 still more to be written on errors in crownwork, bridgework, etc. 
 
 In the chapter on "Absorption of the Alveolar Process and Calcic Deposits," 
 the author states that interstitial gingivitis extends to the alveolar process through 
 the periosteum as well as through the peridental membrane, and not (as dentists 
 usually believe) by way of the peridental membrane alone. 
 
 The reviewer rises from the reading of this book of Dr. Talbot with a high appre- 
 ciation of its contents. He feels assured that any one essaying to treat. interstitial 
 gingivitis, or pyorrhea alveolaris, will be better able to effect results, let his method 
 be what it may, or however skilled he may be through experience. No other work 
 with which the writer is acquainted can compare with this in a clear elucidation of 
 the various phases of this important oral pathological condition. It covers all 
 possibilities, but it will demand serious study. To buy this book and place it on the 
 library shelf for occasional reference will not answer the author's purpose, nor does it 
 appeal to the present writer. The work deals with a scientific problem, and problems 
 of this nature require mental devotion of no ordinary character for their solution. 
 The ideas sought to be taught must be made the operator's own. He must learn to 
 think in the language of the science taught, and then diagnoses become a part of his 
 secondary nature. In the final analysis the writer holds that the pathological con- 
 ditions of the oral cavity and its relations to the general system will and must be 
 conquered by stomatologists, and this accomplished, the health of the world will be 
 placed on a much higher plane than has ever previously been known. 
 
 James Truman. 
 
 '*Dental Cosmos for May, 1913. 
 
From The Dental Digest, August, 1913; 
 
 In this new work from the pen of Dr. Talbot we have the sum and suljslance ot 
 an experience covering thirty-five years spent in honest, intelligent and conscientious 
 research study on the subject of the etiology, pathology and treatment of peridontal 
 disease. The etiological experiments and treatment are made from the viewpoint 
 that disease of the gums ancl the alveolar process are of an infectious nature; but as 
 many different tissues and organs of the body undergo physiological and chemical 
 changes, often due to inflammation from irritating causes, the author has endeavored 
 to separate or classify those inflammations due to infections, and those due to 
 chemical and local changes and constitutional irritations. 
 
 Dr. Talbot, in his introduction to this most valuable book, says: "The attempt 
 has been made in the present work to reduce to order the chaotic notions as to 
 etiology, pathology and treatment which, during the present century, have gathered 
 around the morbid conditions erroneously entitled Pyorrhea Alveolaris. While 
 even erroneous titles may have their meaning so fixed by usage that any danger 
 from the error involved in the title may be practically nil, still this is not the case 
 with the title just cited. It suggests erroneous etiology, since pyorrhea implies that 
 there must always be a flow of pus, and hence that the disease must always result 
 from infection with pus microbes. It implies erroneous pathology and erroneous 
 treatment for the same reason. This being the case, such a title is so dangerously 
 misleading as to compel in the present stage of dental science its modified use as a 
 term for disease. With a view of clearing up this question at the outset by the use of 
 a proper title, I have adopted as a designation for the condition hitherto known as 
 pyorrhea alveolaris the term 'Interstitial Gingivitis'." 
 
 He considers the term interstitial is used by some pathologists in a .limited, 
 obscure sense, but by the mass of dental pathologists, surgeons, physicians, and by 
 medical lexicographers, the term is employed in precisely the sense in which it is 
 used in the present work, and he quotes in support of his assertion the English 
 surgeon and lexicographer, Quain, and Foster's "Encyclopaedic Medical Dictionary" 
 (American). 
 
 One should closely read the introduction and thoroughly digest it, for it most 
 fully describes the work which the author so ably presents to his brothers of the 
 dental profession. 
 
 A glance at the chapter heads will give the reader some idea of the scope of the 
 book: 
 
 Chapter V is of especial interest; it is confined principally to the histological 
 appearance of The Alveolar Process Under the Microscope. Chapter VHI deals 
 with Theories of Interstitial Gingivitis. Perhaps the most interesting chapter is 
 XII — Bacteriologic Researches in Interstitial Gingivitis. A number of extremely 
 interesting experiments are reported, and from these reported experiments Dr. 
 Talbot forms the conclusion that "outside of a few specific diseases of the gums and 
 alveolar process, some of which have been enumerated, no one has demonstrated 
 that specific pathogenic bacterial infection is a cause of interstitial gingivitis, al- 
 though the mouth is known to be the breeding ground of an extensive variety of 
 germs." 
 
 Chapter XVII is devoted to "Local Causes of Interstitial Gingivitis." The 
 close reading by dentist and student is recommended for this chapter; indeed, it 
 would b;- difficult to mention any chapter that would not be good and instructive 
 reading. 
 
 The illustrations are excellent, each one being well described. There is also an 
 index, that indispensable appendix to any book of reference. The book is printed 
 on excellent paper in good readable type, and well bound. We wish it success. 
 
fi„i rlate indicated below, oi 
 This book is due on the date m ^^ borrowing, as 
 
 the Librarian in charge. 
 
'RK651 
 I I Practical manual of dental 
 
 P88 
 
 1913 
 
 cap;+. i 
 
 COLUMBIA UNIVERSITY LIBRARIES (hsLstx) 
 
 RK 651 P88 1913 C.1 
 
 Practical manual of dental castinq : 
 
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