Columbia Umbersitp > in uje Citp of Jfteto $orfe Y^kb »djool of Bental ana #ral £?>u?gi&p a practical meatise Artificial Crown-. Bridge-, and Porcelain-Work 15 v GEOEGE EVANS. FORMERLY LECTURER h.V CROWN- AND BRIDGE-WuRK IN THE BALTIMORE COLLEGE OF DENTAL SURGERY; MEMBER OF THE NATIONAL DENTAL ASSOCIATION; OF THE DENTAL SOCIETY OF THE STATE OF NEW YORK : OF THE FIRST DISTRICT DENTAL SOCIETY OF THE STATE OF NEW YORK; OF THE NEW V'lUK ODONTOLOGICAL SOCIETY: HONORARY MEMBER OF THE MARYLAND STATE DENTAL ASSOCIATION. ETC. Seventh Edition, Revised and Enlarged. WITH 754 ILLUSTRATIONS. PHILADELPHIA : THE S. s. WHITE DENTAL MFG. I 0. 1905. vJ, '-*■ /* '" "2^/ L kiiWl (vP i^KVv^ ^ ' "1 i rg\t^V^ M 9 t~zs /&*tt •^ 17 13 CROWN-, BRIDGE-, AND PORCELAIN-WORK. canal. They should be gently given a slight forward and quick backward motion in the canal, and treated more as reamers than drills. The occasional quick withdrawal of the drill from the canal during the process of drilling will aid removal of the debris. The depth to which a canal may be enlarged or reamed is regulated by its actual length and the above-mentioned conditions, and the diameter of the enlargement by the shape and dimensions of the root. The use of these drills is condemned by some for reasons which are fairly attributable to their careless or improper employment, but they are indorsed, in experienced hands, for their adaptability to the work under consideration. They should be frequently sharpened with a suitably shaped piece of Arkansas stone. The Palmer root-canal excavators also will be found serviceable to open up a canal and enlarge it in accordance with its original shape. While the Gates-Glidden drills are serviceable for the work described, the use of Donaldson broaches is safest and most effective in the upper portion of the canal, especially in those of very small caliber. A 75 per cent, aqueous solution of sulfuric acid carried on a platinum probe, then placed in the canal and at first pumped into it with a smooth broach, is most effective as an aid in opening up very small canals or those partly closed by calcification. In the former case the acid softens the dentin of the sides of the canal so that the friction of a smooth broach will materially en- large it; in the latter, in addition to this effect, it decomposes the calcified contents of the canal. This enlargement of the canal with the smooth broach will usually admit of the introduction of a Donaldson barbed broach, first small, then large, by which the canal can be much more rapidly enlarged. Canals by this method can almost invariably be safely opened and enlarged to the apex, and when so opened they are thoroughly divested of organic matter by the action of the acid. The moderate reaming of a root-canal not only simplifies the operation of filling, but also opens up the ends of the tubuli and facilitates the permeation of antiseptic agents. Treatment and Disinfection — Pulpless teeth are presented for treatment in one of the four f ollowing conditions : 1. Where healthy or non-putrescent pulps have just been extirpated from the canals. PULPLESS TEETH. 19 2. Where on opening into the pulp-chamber it is found empty and dry, with the pulp mummified or calcified in the root-canals, and the root externally in a healthy condition. 3. Where the pulp is found diseased or in a putrescent condi- tion. Fig. 6. 4. Where alveolar abscess- is present and a septic condition of the canals and dentin exists. In the first and second classes the treatment should be directed to assuring a continuance of the existing aseptic condition, and as immediately as possible the filling of the canal; in the third and fourth classes, to bringing about an aseptic condition by dis- infection and sterilization, and making certain of its future main- Fig. 7. tenance, including incidentally the cure of any existing disease of the external membrane or of the alveolus. „ In cases of the first and second classes, if possible, saliva should be excluded from the pulp-chamber and canals during their entire 20 CROWN-, BRIDGE-, AND PORCELAIN-WORK. preparation and filling. If necessary, hydrogen peroxid can be used instead of water. The instruments should be sterilized, and the broaches, if serrated, had better be new. In the third and fourth classes, exclusion of saliva or water is not necessary in the preliminary work on the canal; water may be freely used until the process of disinfection and sterilization is commenced. Then and thereafter its entrance must be prevented. To this end the rubber-dam should be applied if practicable. When it is not, as frequently occurs with roots and teeth badly affected with cervical decay, other means of keeping out moisture should be resorted to. In such cases, during each interruption in the operation the entrance to the canal should be filled with absorbent cotton satu- rated with a suitable essential oil or antiseptic fluid, the saliva being thus excluded. After the canal has been properly opened up and its contents removed, it may be washed out with hydrogen peroxid, and wiped out with absorbent cotton. The use of sodium peroxid is recommended by Dr. Kirk at this stage to open up the ends of the tubnli. The next procedure is to secure as thorough a state of dryness in the pulp-chamber as is possi- ble by forcing into it with a hot-air syr- inge (Fig. 6 and Fig. 7), air at a tem- perature higher — as it leaves the nozzle — than is comfortable for the finger. A root-canal drier, with the end tapered as line as a broach at the point, is then introduced into the canal. The writer prefers the form in which the point is made of silver and the bulb portion of copper (Fig. 8). As silver possesses re- markable properties as a thermal con- ductor, the heat is transmitted to the point of the probe very rapidly. The probe being inserted as far as possible up the canal (Fig. 9), the patient is directed to raise the hand as a signal should the ii eat cause pain, when the probe must be moved up and down or withdrawn for a moment. This procedure, following the previous application of the hot air with the syringe, evaporates the moisture and aids the Fro. 8. Fig. !). PVLPLESS TEETH. 21 escape of any gases present in the root-canals and the open ends of the tubuli. The point of the root-canal drier acts as a sterilizer, and may be applied so hot as to carbonize any organic matter which it reaches in the end of the canal, and a portion of this can be re- moved each time on its point. As the silver point can be tapered as small as the finest broach, canal-contents impossible to remove may be reached and rendered inert. In cases of the third or fourth class, sepsis being present, the heat is very serviceable, as it aids the escape of gases from the canal and dentin and acts as a germicide. When in this dry and heated condition, the dentin is in the best possible state for the application of antiseptic agents. Use of Antiseptics. — Great diversity of opinion exists as to the suitability of various antiseptics to the needs in treating tooth- structure, their effectiveness and permanency when so used, singly or in combination, and their adaptability to various conditions. Many of the antiseptics in common use being coagulants of albu- min obstruct the dentinal tubuli, and their diffusibility through t lie dentin is consequently self -limited. To this class belong carbolic acid, creasote, and the like. They are not entirely non-diffusible in devitalized dentin or cementum, as decomposition effects ele- mentary changes in the contents of the tubuli, but their action is slow and limited as compared with that of some other agents, as the essential oils. They are also irritant, and unsuitable in cases where an acute or chronic inflammation of the peridental mem- branes is to be treated. The essential oils, which are non-coagulative in their action, have greater diffusibility, and, according to Miller, Harlan, and others, possess much greater antiseptic power than was formerly attributed to them. Acidulated solutions of mercury bichlorid, hydrogen peroxid, sodium peroxid, — especially in preliminary treatment, — and preparations of iodin that exert a chemical action and retain their antiseptic properties for a great length of time are the most suitable. The selection of antiseptic agents is therefore important, and the choice is indicated by the conditions presented in a pulpless tooth. Teeth from which a healthy pulp has just been extracted, or in which the canal is aseptic, differ in their requirements from those in which sepsis of dentin or diseased or putrescent pulps are present. 22 CROWN-, BRIDGE-, AND PORCELAIN WORK. In the first-mentioned conditions, favorable results usually follow root-filling, with or without antiseptic treatment, the advan- tage of the antiseptic agent in the canal being only to better assure the continuance of the state of asepsis. When a healthy pulp has just been extirpated, and immediate root-filling is practiced, the use of carbolic acid, creasote, or solution of zinc chloric! is indi- cated. The minute fibrous connections with the walls of the canal and the vessels at the apical foramen are severed, and the action of an escharotic antiseptic agent is in fact required, as it acts as a coagulant and instantly seals up the ends of the tubuli. If immediate root-filling is not to be practiced, then the prescrip- tion of such agents as the essential oils, with aristol or iodoform, seems more suitable, as by their action a sort of mummification of the non-vital organic matter follows. Moreover, the oils possess advantages over the coagulants in that they are not miscible in water, and are less easily eliminated. Their use will tend better to perpetuate an aseptic condition. In the second class of cases, — teeth with sepsis of dentin or having diseased or putrescent pulps, — we need the intervention of agents which will not only destroy ptomains, but which will exert a chemical action on sulfuretted hydrogen and ethereal ammoniacal gases, the products of putrefaction, and entirely eliminate them. On this depends the successful treatment of such cases, as the ex- pansion and pressure of tbese gases are a certain cause for constant peridental inflammation, and so long as they are present in the slightest degree in a canal it is in an unsuitable condition to be closed. Carbolic acid, creasote, or the essential oils, under such circumstances exert no chemical action on these gases, merely dis- guising their odor, though it is true that by repeated dressings of cotton saturated with one of these agents the gases are absorbed by the cotton and slowly eliminated. What is required is the action of an agent whose elements pos- sess an affinity for the gases, and so will immediately decompose them, forming new combinations and entirely changing their character. In accordance with these principles, iodin is indicated as prefer- able in practice to the other agents mentioned. Its effects are best obtained from some one of the preparations now in use, — aristol, for instance, — whose odor is entirely unobjectionable, in a strong solution in one of the essential oils. In the writer's practice PVLPLE88 TEETH. 23 the oils of cloves, cassia, and eucalyptus are favored for this pur- pose, the first named being reckoned more sedative in its action than the others. He makes it a point to flood the canal with the solution, thereby to some extent permeating the dentin as well as the cementum at the apex. A more complete saturation can be accomplished by drying and heating the dentin and applying the solution a second time, or by filling the canal with cotton saturated with it, hermetically inclosing it, and letting it so remain for a day or two. As aristol, oil of cloves, and cassia have a tendency to slightly discolor dentin, their use should be confined to the extremity of the root-canal, and plain oil of eucalyptus or myrtol used in the orifice and coronal section of the tooth where maintenance of the natural color of the crown has to be considered in an operation. The disadvantage of immediate root-filling is that, should some fragment of the pulp remain in the extremity of the canal, it fails to receive the benefit accruing from the reapplication of antisep- tics, which would better assure its inertness by mummification. There is such a thing as over-treatment, — an unnecessarily frequent renewal of antiseptic dressing in root-canals, thereby aggravating or producing irritation of the pericementum at the apex of the root. Such cases may be relieved by washing out the canal with alcohol and then applying the alcohol on the dress- ing, instead of the agents previously employed, until the inflamma- tion subsides. The dressing of root-canals is best performed with the aid of the ordinary smooth, flexible rectangular broaches; also root-canal dressers, such as the How. The form of these instruments permits fibers of cotton to be easily wound around them lengthwise and over the point in one connected mass. When the cotton is intro- duced in the canal, it is retained on and carried forward by the in-, strument, which, when withdrawn, leaves the cotton in position in the canal in the form of a cone or tampon that will favor the. escape of gases, and it may still be easily removed^at any time. After one or more treatments in the manner described, between which, if interspersed by intervals of time, the antiseptic agents must be hermetically sealed in the cavity with gutta-percha, the canal is dried and the foramen closed. Closure of the Apical Foramen and Filling of the Canal. — The object of root-canal filling is the maintenance of an aseptic 24 CROWN-, BRIDGE-, AND PORCELAIN-WORK. condition in a sterilized root-canal by hermetically closing it at both the. apical foramen and the orifice, and thus preventing its infection by the entrance of either fluids or gases. Gutta-percha and zinc oxychlorid are generally accepted as most suitable for the purpose. Either gutta-percha in the form of chloro-gutta- percha, or zinc oxychlorid mixed thin, can be pumped or placed in the extreme end of the canal with the aid of a broach or fine-pointed probe. This is one of the advantages that commend the use of these materials. When the chloro-gutta-percha has been placed in the apex, the remainder of the canal can be filled with the prepared cones of solid gutta-percha until no more can be inserted. A current of hot air should then be thrown on the protruding ends of the cones at a temperature sufficient to soften them and warm the dentin, when they should be gently pressed, but not suddenly pushed, up in the canal. A slight twinge of pain to the patient will usually be the signal of their complete impactment in the canal. The solid gutta-percha absorbs what little chloroform was present in the chloro-gutta-percha, and the heat also aids its evaporation, so that the shrinkage so often urged as an objection against the use of chloro-gutta-percha is reduced to a minimum. An advantage possessed by zinc oxychlorid over other mate- rials is its antiseptic qualities; its disadvantage, the difficulty at- tending its removal from the extremity of the canal should super- vening conditions require it. For this reason the apex and extremity of the canal may be filled with gutta-percha, and then the orifice and pulp-chamber with oxychlorid. This combination forms an ideal root-canal filling, as the oxychlorid hermetically closes the orifice of the canal and prevents its infection from the oral cavity. When metallic points of lead and copper shaped to fit are used to fill root-canals, unless a small quantity of zinc oxychlorid is placed in the extremity or on the point used, the complete closure of the canal is doubtful. The use of cotton as a filling in root-canals is to be condemned, unless it is sterilized 1 or iodoformized and saturated with chloro-gutta-percha or zinc oxychlorid previous to insertion. Asbestos is given preference to cotton by some. Tin or gold foil is difficult to insert without 1 Cotton may be sterilized by immersing it for a time in a saturated solu- tion of iodoform in ether, and then drying. It should be kept in a tightly- corked bottle. When this plan is followed, the odor of iodoform is avoided in the operating-room. PULPLESS TEETH. 25 leaving vacuoles. Paraffin combined with a small quantity of aris- tol, as a material to fill root-canals, has been suggested by Dv. Kirk, especially after the use of sodium peroxid. This agent, being a most active solvent of albuminous matter, in a measure frees the ends of the tubuli or a canal of their organic contents, a condition favorable for the use of paraffin. Paraffin is aseptic and melts at a low temperature, and with a heated root-canal drier can be flowed into the ends of the tubuli or into a minute canal not con- sidered safe to open up extensively. Balsamo del Deserto can be used in the same manner. Ordinary gutta-percha should be used to close a foramen when an abscess lias just been treated by injecting through it. The length of the canal should be measured with a probe, and gaged with a small perforated disk of rubber-dam slipped upon the instrument. The gutta-percha should then be carried to position on the point, allowance being made for the displacement of the instrument. As oil of eucalyptus is a solvent of gutta-percha, the application of this oil, alone or in combination with iodoform or aristol to the surface of the gutta-percha, is recommended in the final treatment, as better adhesion to the walls of the canal is thus ob- tained. Ample room should be left in any root- canal which is to receive the post of a crown, as any part of the canal not occupied by the post will be filled by the retaining material. "When a post has been fitted to a canal pre- vious to the closure of the foramen, the point of it may often be utilized to aid in the final pressing of the gutta-percha to place by warm- ing the post and wiping the point with oil of cloves to prevent adhesion of the gutta-percha. "When zinc oxychlorid is used, the foramen should preferably be first closed with a small quantity of either solid gutta-percha or the chloroform solution of it, to avoid the accidental protrusion of the oxychlorid, which is then pumped up the canal, and the post inserted. "When the cement is about half set, the post is seized with pliers and withdrawn and not again inserted until the cement is perfectly set. In this manner an oxy- chlorid socket is formed into which the post will accurately fit. G, Gutta-percha. 0, Oxychlorid. P, Post. 26 CROWN-, BRIDGE-, AND PORCELAIN-WORK. (See Fig. 10.) The same can be done with the post of a finished crown. A pulpless tooth presented for crowning, the roots of which have been treated and filled in some previous operation, should be carefully examined. If any doubt is entertained as to its hygienic condition it should receive the antiseptic treatment above described, as the ultimate success of crown-work depends largely upon the thoroughness of these preliminary operations. CHAPTER IV. Chronic Alveolar Abscess, the usual forms— alveolarotomy— amputation of the apex of A ROOT. Many teeth and roots presented for crown-work are affected with chronic alveolar abscess. A general description of an effec- tive method of treatment is therefore properly associated with a discussion of the subject. The cause of chronic alveolar abscess will be found in a con- tinuation of those conditions which originally produced the acute form. The tooth or root being pulpless, septic gases, generated by the decomposition of organic matter in the root-canal and in the tubuli of the dentin, find an outlet through the open foramen into the apical space, causing pericementitis and formation of pus. The general treatment consists in the removal of all septic matter and gases from the root-canal and dentinal tubuli, the destruction of the pus-sac, the application of suitable therapeutic agents, and the adoption of measures to prevent further formation of pus. The Usual Forms. — Chronic alveolar abscess is usually found in the following forms : First, abscess with a fistulous opening in the gum, and accessible through the root-canal and foramen of the root. Second, abscess with fistulous opening, but not accessible through the apical foramen. Third, abscess from which pus dis- charges through the apical foramen and root-canal, with no open- ing through the gum. In the treatment of abscess of the first form, the canal should be enlarged as described in the treatment of pulpless teeth, and the foramen opened, if possible, with a smooth broach without the use of a drill. Aromatic sulfuric acid, on cotton, placed in the end of the canal for a day. will usually open up the finest foramen. A small quantity of 75 to 90 per cent, aqueous solution of sulfuric acid pumped into the extremity of the canal will often enable a broach to instantly effect a passage. Tepid water is then forced through the foramen with a fine-pointed syringe (Fig. 11) 28 CROWN-, BRIDGE-, AND PORCELAIN-WORK. introduced well up the canal, and packed in with gutta-percha; or it may be pumped up with cotton on a broach until it passes into the abscess and out through the fistula. Hydrogen peroxid is next used in the same manner. Aromatic sulfuric acid may also be injected through the fistulous opening into the abscess. In abscesses of the second form, where it is impracticable to treat through the foramen, the canal should be thoroughly disin- fected, and a direct opening into the abscess effected by the track of the fistula, enlarging it when necessary. The abscess should then be thoroughly injected with hydrogen peroxid, and after- ward with aromatic sulfuric acid, by introducing the fine point of a syringe into its -deepest parts. The fistula must be kept open while treatment is conducted by inserting in it, at each injection, Fig. 11. a strand of twisted cotton saturated with oil of cloves, the patient being directed to remove it in a few hours, or the next day, for which purpose the end should be left protruding. When the apical foramen is open, one injection through it is frequently suffi- cient to cure an abscess; but when the foramen is closed and the abscess is treated through the gum, several in- jections are generally necessary and the result not positive. In case of "blind abscess," the third form, first open, clean, and disinfect the canal, and enlarge the foramen with sulfuric acid and Donaldson broaches, so that the largest sizes will pass freely into the abscess. Through the enlarged foramen inject and wash out the cavity of the abscess — at first daily — with hydrogen peroxid. Insert a small probe in the canal, pack the orifice with gutta-percha, press on the gutta-percha, and withdraw the probe. The aperture left by the probe furnishes a small vent. Continue this line of treat- ment until evidence of suppuration ceases, then temporarily pack the canal with cotton slightly moistened with oil of cloves or any other of the suitable essential oils, seal the orifice of the canal, and temporarily fill the cavity. Should the indications appear favorable on the removal of this dressing, or any subsequent one similarly CHRONIC ALVEOLAR ABSCESS. 29 Fig. L2. Fig. 13. inserted, close the foramen with a cone of gutta-percha, placed in position gently so as to avoid protrusion into the apical space or causing pressure. This method, if skilfully practiced, will usually effect a cure of this troublesome form of abscess. Should this treatment fail, an opening through the gum into the abscess must be obtained, with a lance and drill, and the same course pursued as in the first form of abscess. Alveolarotomy. — For this operation the length of the root and position of the apex should be first accurately determined. This is best done by introducing a broach with a hook point through the canal and foramen into the abscess and then slowly withdraw- ing it. In the withdrawal, the hook by catching on the apex shows both the position and the length of the root (Fig. 12). A small pellet of gutta-percha or a little disk of heavy rubber-dam placed on the broach at the point where it enters the root or tooth, as shown at A, Fig. 12, will form an accurate gage. After the with- drawal of the broach a straight fine probe is passed up the canal through the foramen into the abscess and left there in position, the exposed por- tion (A, Fig. 13) fairly indicating the direction in which the root points, and should no considerable curve exist toward the apex, the line in which the abscess cavity is most likely to be found. The marked broach is then placed externally with its shank exactly parallel with the probe in the canal (see B, Fig. 13), and the line of the broach and more especially the location of the hook point marked on the gum with carbolic acid. A few shreds of cotton closely twisted around the broach, especially at the point, will aid in carrying and holding the acid. In this manner the line of the root and the position of the end, allowing for a slight curve tow T ard the apex, can be located within a small fraction of an inch, and the cavity of the abscess, which may be a little to the right or left of the point, determined with sufficient accuracy. The membrane 30 CROWN-, BRIDGE-, AND PORCELAIN-WORK. Fig. 14. at the spot marked as over the end of the root is then punctured and entrance to the end of the root and apical space and abscess effected through the bone with a small spear-shaped bur and spoon- shaped excavators. The fine probe protruding through the fora- men into the abscess will aid in locating the abscess cavity and apex of the root. The membranes may be anesthetized with an injection of a 5 per cent, solution of eucain previous to the opera- tion. A more definite method practiced by the author, in cases of very long roots, is, after getting the length of the root with the broach as previously described, to introduce a flexible straight probe up the canal, through the foramen into the abscess. The probe is removed, warmed, and again introduced, with a film of gutta-percha placed on the shank to steady and indicate its exact position. The broach indicating the length of the root is placed externally against the surface of the gum, over the root, with its shank and handle parallel to the shank and handle of the probe in the canal. Shanks and handles are then connected with a piece of softened impression-compound, the compound is slightly chilled, and the instruments removed. (See Fig. 14.) If on removal the broach and probe are found not to be exactly parallel, they are made so. By this means on the reinsertion of the probe in position in the canal doubt is removed as to the location of the apex of the root, as it is not possible to always positively parallel the broach and probe while the latter is hidden in the root-canal, where also it is often far from being steadily fixed. In these cases, curetting of the cavity of the abscess and apex of the root is most effective, but the removal of healthy bone tissue should be avoided as much as possible, as the stability of the root is proportionately impaired thereby. An entrance into the apical space can be made almost pain- lessly in the following manner, as described by Dr. G. V. Black :* "The mucous membrane is first dried at the point at which it is desired to make the opening, and napkins are so placed as to keep it dry. Then a plugging-instrument with fairly sharp ser- "Ameriean System of Dentistry," vol. i, page 928. OHHONIC ALVEOLAR ABSCESS. 31 rations and of convenient shape is selected. The point of this is dipped into a 95 per cent, solution of carbolic acid, and a drop conveyed to the mucous membrane; this will at once pro- duce a white eschar. Then a slight scratching motion with the serrated point is begun, with a view of removing the tissue that is whitened. This is continued until the carbolic acid is thick with the debris of the tissue torn up, then it is dried out and another drop added, as before, and the process continued. This is repeated as often as may be necessary, going deeper and deeper into the tissue in the desired direction until the bone is laid bare. Then a fresh drop of the acid is placed on the bone, and the periosteum carefully raised over a sufficient space; then with a sharp chisel cut through to the peridental membrane. This will generally cause some pain and some bleeding, but after giving a little time for this to cease, and adding more of the acid, the apical space can usually be reached without difficulty. No blood should be drawn at any time during the operation, except in penetrating the wall of the alveolus. In doing this no tissue is removed until it is anesthetized by the carbolic acid. This is a little tedious, but it is almost painless, and the general effect is usually better than by other modes of penetrating the apical space. The carbolic acid has the effect of modifying the pain, and the opening left does not close so readily." A period of entire cessation of discharge of pus is to be con- sidered the most favorable indication of successful treatment. Thorough disinfection and sterilization of the dentin and root- canals are included in the preliminary treatment of alveolar abscess. As soon as the treatment is followed by favorable indi- cations, the foramen should be closed while the fistula is yet open. Any further treatment considered necessary can be conducted externally through the fistula. This may be facilitated by en- larging the orifice with tents of cotton saturated with oil of cloves. Enlargement of the fistula tends to encourage the process of granu- lation in the region which has been occupied by the abscess, espe- cially when a more than usual necrosed condition of the bone requires its removal. After the abscess has been cured, the root-canals are filled as described on page 23. Aromatic sulfuric acid is a powerful astringent and germicide. It will be found most useful in cases where a slightly necrosed 32 CROWN-, BRIDGE-, AND PORCELAIN-WORK. state of the wall of the alveolus exists. Its use should, however, be limited, and in subsequent external treatment through the fistula some of the other therapeutic agents should be employed, as the hydrogen peroxid, or the essential oils or carbolic acid, alone or combined with one of the preparations of iodin. 1 Injections of sulfuric acid in the region of the mental foramen should be made cautiously, and it should not be applied to an abscess bordering on the antrum until the operator is positively assured that the abscess does not open into that cavity. Amputation of the Apex of a Root. — In long-neglected alveo- lar abscess, the pus-cavity occasionally involves the alveolus in such a way as to destroy a considerable portion of the pericemen- Fig. 15. turn of the end of the root. The cementum of that part is consequently devitalized, and the portion of the root affected becomes degenerated in struc- ture, and saturated with septic matter. In this condition it acquires the character of a foreign substance, proves a constant source of irritation, and defies all efforts of the membranes to perfectly inclose or encyst it. In such cases, when curetting of the abscess cav- ity and end of the root has failed, amputation of the portion of the root which is denuded of pericemen- tum is the best course to pursue. An opening is made in the soft tissues over the affected part in the manner de- scribed on page 29, and gradually enlarged with a tent of lint or cotton until the diseased territory is fully exposed (Fig. 15), when the devitalized end of the root and any necrosed bone in the territory are removed, and the end of the root smoothed. Only enough of the end of the root should be excised to thor- oughly remove the affected part, as an excess will proportionally lessen its stability and usefulness. The canal should be filled solidly with gutta-percha or preferably zinc oxychlorid previous to the amputation, so that when the end of the root is excised the stump will be left smoothly and snugly filled. Cocain can be used in this operation. 1 For an extended consideration of this subject the reader is referred to Dr. J. N. Farrar's articles on "Sulphuric Acid v. Creasote in Treatment of Alveolar Abscess," commencing in Dental Cosmos, vol. xx, No. 7, and Dr. G. V. Black's article in the "American System of Dentistry," vol. i, page 929. CHRONIC ALVEOLAR ABSCESS. 33 The orifice of the cavity in the gum should be kept open and injected daily with a mild antiseptic solution by the dentist or patient until the cavity is filled by granulation. In cases where extensive necrosis of the alveolar process has existed, in addition to the daily injection the cavity should be packed with a suitable antiseptic dressing. Balsam Peru has been found by the author to be a suitable agent for the purpose, as it assists the process of granulation. When the healing process is completed, crown-work can be proceeded with. The amputation of roots requires skill and experience, and had better be confined to the front teeth or those with a single root, except in the hands of experts. The performance of this opera- tion without preliminary treatment, by making a transverse in- cision across the line of the end of the root, is to be condemned. The hemorrhage obstructs the view of the parts and renders liable the removal of an unnecessary amount of tissue, besides it in- creases the severity of the operation. CHAPTER V. Shaping Teeth and Roots for Crown-Work. PRINCIPLES INVOLVED — PREPARATION OF TEETH OR ROOTS FOR COLLAR CROWNS, AND INSTRUMENTS USED— FOR READY-MADE PORCELAIN CROWNS — SPECIAL PREPARATION OF BADLY DECAYED TEETH OR ROOTS. Principles Involved. — The principles governing the shaping of the surface of a natural crown or root for any style of artificial crown with a collar attachment require that the cervical portion of the natural crown and root shall be given a form that has longitudinally parallel sides gaged to the line of the periphery of that part, and that any of the coronal section present below it shall be reduced at least sufficiently in size to come within this line. Such a form is necessary to admit of a perfect adaptation of the collar. Fig. 16. Preparation of Teeth or Roots for Collar Crowns, and Instru= ments Used. — The coronal section of a natural crown to be prepared is usually first ground on the occluding surface with as large a corundum-wheel as the case will conveniently admit (Fig. 1G). Molars and bicuspids for all-gold crowns should have enough substance removed to make a small space between them and the antagonizing teeth. The approximal sides of the cervix should be reduced sufficiently to allow a free space between the gold collar when adjusted and the cervices of approximal natural teeth or artificial crowns, to make room for the gum-septa. The approximal surfaces are removed straight from the cervical border 34 SHAPING TEETH AXD ROOTS FOR CROWN-WORK. 35 to the occluding surface, using corundum or carborundum and rubber disks (Fig. 17), straight-sided or cup-shaped, to get the angle, and occasionally thin separating files; and last of all, as in- jury to the approximal teeth is then more easily avoided, the labial and palatal portions, for which small corundum-points (Fig. 18) and wheels are best adapted. The corners are then rounded. The Fig. 1; Fig. 18. cervical portion of roots for collar crowns, which includes the junction of the dentin and enamel, is trimmed so that the sides as illustrated at A, Fig. 19, are level and parallel with the line of the root, and as deep as the collar is to be placed (Fig. 20). For this work small corundum-points, trimmers, and files can be used. Fig. 19. Fig. 20. Fig. 21. Fig. 22. i Ih n km s m I Fig. 23. § 1 I * Trimmers of the shapes and sizes illustrated in Fig. 21, preferably made with cross-cut serrations, in the ordinary hand-piece or in the right-angle attachment, will easily and quickly accomplish this. Fig. 22 illustrates another style, in the form of a triangular pyramid, which can be used as a scraper in a hand-socket, bracing the hand by resting the thumb on the adjoining teeth. The points 36 CROWN-, BRIDGE-, AND PORCELAIN WORK. should be tempered very hard. Files and serrated scrapers shaped as shown in Fig. 23 are useful in rounding angular portions. A smooth surface should be given the cervix. On approximal sides and the curves to the other sides, medium coarse corundum tape and paper disks can be used for this purpose. In pulpless teeth, the use of excising forceps should be avoided unless the parts admit of it without serious shock to the root. The best method of amputation is to make a succession of holes with a spear-shaped drill across the portion to be removed, and then cut between the holes with a fissure-bur or corundum-disk, which will permit of easy removal of the part (Fig. 24). In preparing incisors and cuspids for gold collar crowns with porcelain fronts, where the pulp is to be preserved, the labial surface and incisal edge should be ground down as much as Fig. 24. Fig. 25. Fig. 26. Fig. 27 Fig. 28. Fig. 29. possible without exposing the pulp or subjecting it to irritation; the palatal portion at an angle from the cervical border to the incisal edge, enough to level its prominences of contour and form a slight space between it and the antagonizing teeth (Fig. 25). Pulpless incisors and cuspids should be prepared by grinding the labial face to the gum-margin, with the palatal portion slightly projecting and squared off to the inner line of the root-canal. (See Fig. 20.) Bicuspids which are to have porcelain fronts are given the same general form (Fig. 27). In preparing the roots of incisors, cuspids, or bicuspids, it is advisable to let the labial section of the end of the root project slightly beyond the gum-margin until the collar has been fitted, when it can be reduced. Bicuspids and molars with or without pulps, for all-gold crowns, SHAPING TEETH AND ROOTS FOR CIWYX^YORK. 37 should have as much of the natural crown left as possible (Figs. 28 and 29). To give a thimble-shaped form is unnecessary and un- desirable. While the approximal sides might very slightly taper toward the occluding surface, the other sides should be as nearly parallel as possible. This form is preferable in constructing the crown and is more favorable for its attachment. The proportion of teeth with living pulps to which gold crowns should be applied is small. Such cases are those in which exten- sive decay has involved considerable of the coronal section of the tooth and caused more or less calcification of the pulp. The preparation of these cases, of which Fig. 30, a bicuspid, and Fig. 31, a molar, are typical, consists in the trimming of the decom- posed enamel at the approximal sides, a moderate reduction of the occluding surface, and the removal of enough from the contour of the labial and palatal surfaces to allow the edge of the collar to Fig. 30. Fig. 31. Fig. 32. n Kj Fig. 33. spring over and be closely adjusted at the cervical section just under the free margin of the gum. Trimming of the enamel for the purpose of deeply imbedding the edge of the collar under the gum-margin, so that it shall closely approach the perice- mentum, is unnecessary, either for the purpose of retention of the crown or for the preservation of a tooth with a living pulp. Irritation of the pericementum by impingement of the collar would eventually result in recession of the membrane and ex- posure of the edge of the collar. Fig. 31 and Fig. 33 show the typical bicuspid and molar prepared for the construction of the metallic crowns, the natural teeth having been trimmed and the cavities sterilized and filled with amalgam. Extremely short teeth and teeth slightly imbedded in the tissues, as many third molars are, do not require as much shaping as long bicuspids and first molars. 38 CROWN-, BRIDGE; AND PORCELAIN-WORK. It should be borne in mind, however, that unnecessarily cut- ting away the enamel and dentin of teeth with living pulps leaves them in an extremely sensitive condition, and is likely to result subsequently in some serious lesion of the pulp. Slight sensitive- ness, such as may be caused by excessive shaping, is relieved by drying the exposed dentin with hot air and applying carbolic acid two or three times as required. When this treatment is not suffi- ciently effective, a temporary cap of pure gold, about No. 34 gage, can be quickly constructed and cemented on with gutta-percha. A small quantity of a compound of oil of cloves, carbolic acid, and chalk (described on page 9) placed in the center of the cap acts as a sedative and remedial agent. For Ready=Made Porcelain Crowns, roots are usually ground level with the margin of the gum. The palatal portion of the end of the root in some cases may be allowed to project a trifle beyond the margin, but the labial aspect should be trimmed a little below, especially on the front teeth, if it is desirable to conceal the joint. The root-canal is shaped to the form of the post or dowel to fit it tightly. (See Part II, Chapter III, "Porcelain Ready-Made Crown System.") The occluding edges or surfaces of antagonizing teeth should be removed sufficiently to allow ample space for the artificial crowns or to favor them in occlusion. This is especially necessary where the occluding tooth, in the absence of an antagonist, pro- jects beyond the proper line of occlusion. When the approximal teeth crowd against and overhang the end of a root, so that the space for the artificial crown at the occluding surface is narrower than at the cervical section, — measured from mesial to distal side, — the sides of the root should be trimmed so as to give a free space between it and the sides of the approximal teeth. The approximal teeth may also be pressed away by packing on each side of the root w T ith gutta-percha, or a small portion of their in- terfering surfaces removed, as shown in typical cases in Figs. 34 and 35. Corundum or Vulcarbo wheels or points should be kept wet and cool during use in all such operations in the mouth. A piece of sponge, held against the wheel with clamping pliers, or a porte- polisher, such as is used for carrying a small piece of wood in cleaning or polishing the teeth, answers the purpose admirably, and also protects the tongue and cheek from injury. SHAPING TEETH AXD ROOTS FOR CROWX-WORK. 39 Special Preparation of Badly Decayed Teeth or Roots. — The temporary exposure of the end of a root or of the cervical por- tion of a crown for the purpose of facilitating or simplifying a crowning operation, especially in the adaptation of a collar, is effected by inserting in the pulp-chamber or the root-canal a piece of gutta-percha large enough to admit of a portion being brought over against the investing membranes, to compress them for a day or more. In some cases to secure attachment for the gutta-percha, a plug of wood may be inserted temporarily in the root, and the gutta-percha packed around it. Roots can thus be exposed to the border of the alveolar process if desired. In bicuspids and molars, when decay extends up on the cervix farther than will the edge of the artificial crown or the collar, the gums should be pressed up as described, the decay removed, retaining-pits made, and the cavity filled with amalgam shaped to the contour required (Fig. Fig. 34. Fig. 35. 30). In such cases the amalgam will generally be in close prox- imity to the pulp and the cavity frequently of a form not favor- able to the retention of the filling. To avoid irritation from thermal changes and better retain the filling a moderately thin mixture of oxyphosphate may be first placed in the cavity, the amalgam then pressed into it and the oxyphosphate forced out, especially at the margins where the amalgam must be brought into direct contact with the tooth-structure. In incisors and cus- pids, when decay has deeply destroyed a portion of the side of the root, a tight-fitting tube of a metal to which amalgam will readily adhere, and of such size as to admit the pin of the crown, may be inserted in the root-canal, cemented with oxyphosphate, and the decayed portion restored with the amalgam on the side of the root. The post of the crown should be tapered at the end, and inserted 40 CROWN-, BRIDGE-, AND PORCELAIN-WORK. in the canal as deeply as possible beyond the end of the tube, to gain additional strength by distributing the leverage along the whole line of the root. In some such cases a better method is to fit and cement a pointed post as far up the canal as it can be safely introduced, leaving the end protruding beyond the gum. Then shape the side and end of the root with amalgam and cap with a platinum and porcelain jacket-crown (Part IV, Chapter VIII). Fig. 37 shows a typical central and bicuspid of this character. "When an incisor or cuspid crown post is to be inserted and the root-canal is enlarged from decay or excessive reaming, the defect in relation to the post of the crown can be remedied in the follow- Fig. 36. Fig. 37. Fig. 38. Fig. 38a. Fig. 39. Fig. 40. i ing manner : Fit a tapering post of medium size with the point reaching the extremity of the canal. Close the foramen with a very small point of gutta-percha so that it will not interfere with the insertion of the post. Fill the canal with a thin mixture of Ash & Sons' "Rock Cement" (a zinc oxychlorid which sets in three minutes), insert the post, and in exactly thirty seconds re- move it. Instantly wipe off the post and reinsert it. The tem- porary removal of the post prevents the adhesion of the cement to it, so that when the cement has set the post can be removed, and you have a close-fitting socket for it. In setting a gold cap-crown on a badly broken-down tooth or root, a post of platinum or iridio-platinum wire should be fitted SHAPING TEETH AND ROOTS FOR CROWN-WORK. 41 to the root-canals (Figs. 37, 38, 38a, 39, and 40). The end can be bent or a piece of gold or a globule of gold melted to it. The post should then be barbed, the point fastened in the root with a little oxyphosphate or zinc oxychlorid, and the crown built down about two-thirds its length with a quick-setting amalgam, 'to be shaped when hard and then slightly notched to furnish a better attachment for the cement with which the cap is set. Roll- ing the wire used to form the posts under the flat side of a file before using will uniformly roughen the entire surface in a manner most favorable to the adhesion of the cement. Screws may be used as posts to support the amalgam, but cemented posts are preferable. To safely retain the amalgam in position during the setting, a previously made and properly fitted collar of thin German silver or copper plate, not over Xo. 35 gage, may be used. When the amalgam has set, at a subsequent sitting, the metal can be readily stripped from its surface, which should be dressed down with the revolving trimmers evenly to that of the surface of the root or crown. In such cases it is presumed that the gold cap will entirely cover the exposed portion of the amalgam. PART II. ARTIFICIAL CROWN-WORK. PAET II. CHAP TEE I. Artificial Crown-Work. FIRST AUTHENTIC ACCOUNT OF ARTIFICIAL CROWN OR PIVOT TEETH— THE FIRST PORCELAIN PIVOT TEETH — GOLD PIVOT TEETH— FIRST PORCELAIN AND GOLD PIVOT TOOTH OR CROWN— RICHMOND PORCE- LAIN AND GOLD COLLAR CROWN — THE EARLIER OPERATIONS- MORRISON AND BEERS CROWNS— THE FOSTER AND LAWRENCE CROWNS— THE MACK AND HOWLAND-PERRY CROWNS— THE GATES- BONWILL CROWN — THE HOW CROWN— THE WESTON CROWN — THE NEW RICHMOND PORCELAIN CROWN— ADVANTAGES CONFERRED BY IMPROVEMENTS IN CEMENTS— CLASSIFICATION OF CROWN-WORK. First Authentic Account of Artificial Crowns or Pivot Teeth. — The first authentic account we have of the use of artificial crowns or pivot teeth is given by Fauchard, in his work entitled "Le Chirurgien Dentiste on Traites des Dents/' in 1728. Fig. 41 illustrates the crown he describes. The root was ground level with the surface of the gum, the root-canal enlarged, cleaned, and filled with lead. A hole was drilled in the lead and the rough-surfaced post was forced into the soft metal to secure it. The other end of the post was Jj a fastened in the crown, which was either a natural crown or one made of ivory. De Chemant described the use of porcelain for the construction of pivot teeth in the early part of the last century. From that time on porcelain has been used and has gradually, for the most part, superseded other mate- rials for the construction of crowns. The First Porcelain Pivot Teeth.— The porcelain pivot tooth or crown (Fig. 42) was the form used for many years, until re- 45 Fig. 41. C I Fauchard's "Dent a Tenon." 46 CROWN-, BRIDGE-, AND FORCE LAIN -WORK Fig. 42. Pivot Tooth. cently. When first introduced it was attached to the root by means of a hickory-wood pin or pivot, one end of which fitted the hole in the center of the crown and the other that of the root-canal. The moisture, by swelling the wood, securely fastened the pivot in both tooth and root. It was found that the wooden pivot in time caused decay of the root, and was liable to fracture it by expansion; it also affected the breath. These objections led to the introduction and use of a gold pivot instead. Gold Pivot Teeth. — These gold pivots were variously secured to root and crown. In the crown the pivot was fastened by incasing it with wood or by skilfully flowing a little gold solder around the part of the pivot which set in the porce- lain, and to the root by fitting in the canal a piece of hickory and inserting the pivot into the wood, or, by twisting fibers of cotton or silk around the post and pressing the crown to position. First Porcelain and Gold Pivot Tooth or Crown. — The porcelain pivot tooth mounted by these methods was superseded by the use of a plain plate porcelain tooth, backed with gold and sol- dered to a piece of plate stamped out to accurately fit the end of the root and soldered to the pivot or pin, as shown in Fig. 43. A later improvement in the attachment of the crown consisted in the use of a gold tube, which was screwed into the root and into which the pivot was tightly fitted. This later method was devised to avoid the objectionable features connected with the use of wood. The transition from this last- mentioned method to those of modern crown-work, though most important in their results, is not so marked as regards constructive details. Richmond Porcelain and Gold Collar Crown. — The gold collar crown w T ith porcelain front of present use is practically the gold- backed pivot tooth of former years, with the addition of a collar to inclose the end of the root. This addition of a collar, though apparently simple to conceive, was slow of development. It was not until such a form was presented and its advantages demon- Root Prepared for Pivot. Fig. ARTIFICIAL CROWN -WORK. 47 strated by Dr. C. M. Richmond, about 1878, that its true value and possibilities were appreciated, more especially respecting the support it was capable of affording in bridge-work operations. The Earlier Operations. — The earlier operations in porcelain crown-work were almost entirely confined to the incisor and cuspid teeth, the object being restoration for appearance rather than utility. We find, though, on investigating the history of the art, that some effort was also made by a few of the earlier practi- tioners to maintain and restore the usefulness of affected back teeth with crown- work. Prominent among these was J. Paterson Clark, a dental practitioner in London, England, who, as early as 1836, published a description of his method of restoring decayed and abraded molars to usefulness by covering them with gold caps stamped up on a metal die of the tooth. Fig. 44. The Morrison and Beers Gold Crowns. — Similar operations were described and practiced later on in this country by Dr. W. 1ST. Morrison, in 1869, and were brought into more prominence by Dr. J. B. Beers, who, in 1873, secured a patent for his method of capping teeth with gold, as illustrated in Fig. 41. During the progressive modifications in crown-work which evolved from the gold-pivot tooth or crown to the gold-collar porce- lain crown of the present time, many improvements on the original porcelain pivot tooth as a ready-made crown were developed and introduced into practice. One of the first of this character to attain prominence was the Poster crown. The Foster and Lawrence Crowns. — The Foster crown, intro- duced by Dr. E. W. Foster, in 1855, and so named, although similar to one patented by Dr. H. Lawrence, in 1819, differed from the commonly used pivot tooth in having a perforation in the center of the palatal side on a line with the root-canal. The 48 CROWN-, BRIDGE-, AND PORCELAIN-WORK. orifice was shaped to accommodate the head of a screw (Figs. 45 and 46) by which the crown was attached to the root. The object of this form was to dispense with the use of wood as a pivot or post. The Mack and Howland=Perry Crowns. — The first form of porcelain crown introduced which protected the end of the root by the use of cement for its attachment was devised by Dr. C. II. Fig. 45. Fig. 46. Mack, in 1S72. It consisted of a hollow porcelain crown, with a cavity in the base of a shape and size to admit the extremities of pins screwed into the root or cemented in the canal. The crown was cemented on the root over these pins with gutta-percha, amal- gam, or zinc oxychlorid. The Mack crown proved unreliable in practical use because of the insecurity of the attachment. The Howland and Perry crowns, which were so nearly identical that they became known as the Howland-Perry crown (Figs. 47, 48), Fig. 47. Fig. 48. improved on the Mack by imparting to the cavity in the base a better form for the retention of the screws in the cement and a more suitable curve to the base. The Gates=Bon\vill Crowns — The next noticeable improve- ment in all-porcelain crowns appeared in the Gates and Bonwill crowns, the former being the invention of Dr. W. H. Gates, about 1875, and the latter of ""Dr. W. G. A. Bonwill, in 1881. These ARTIFICIAL CROWN-WORK. 49 also were so nearly alike that they were called "Gates-Bonwill" (Figs. 49 and 50). One of the advantages this crown possessed over the Foster was, that amalgam was used for its attachment, protecting the end of the root from decay. The base of the crown Fig. 49. Fig. 50 was concave and the aperture for the post of a triangular form. The crown was secured to the root with a screw-post, or a flat pin with tapering ends, anchored with the amalgam that attached the crown. This crown was extensively used for several years. The How Crown. — The How crown (Figs. 51, 52) was in- vented by Dr. W. S. How, in 1883. Its novel feature was the formation of a sufficient concavity in the palatal side of the in- Fig. 51. Fig. 52. cisors and cuspids to afford space for four pins in the porcelain with room between them for the adjustment of the screw-post. The crown when fitted was attached by bending the pins around the post and packing around them and filling the cavity of the crown with amalgam. The Weston Crown. — The Weston crown, introduced by Dr. Henry Weston about the same time, was similar in principle and structure, with this difference: The Weston post was flat and riveted to the crown before insertion. The post was first cemented in position with a small quantity of zinc oxyphosphate, and the 50 CROWN-, BRIDGE-, AND PORCELAIN-WORK. remainder of the space then filled with either gold or amalgam. Fig. 53 shows the various steps in the operation. Another form of modern introduction, but limited use, was the Brown crown, illustrated in Fig. 54. It was made with a conical base and with a long pin baked in the porcelain. In mounting it, the end of the root was concaved to receive the convex porcelain base. The object of this form of construction was to permit the Fig. 54. Fig. 55. porcelain to be removed in a close bite without materially weaken- ing the crown. The New Richmond Porcelain Crown — In the New Rich- mond porcelain crown, illustrated in Fig. 55, which was also of the all-porcelain variety, a cavity was provided at the base to exert some degree of lateral pressure on the root and thus help to guard against its fracture. The development of what were classed as ready- made porcelain crowns as here traced, brings us to the forms which are now in use and which will be described in the succeeding chapter. Advantages Conferred by Improvements in Cements. — Doubtless much of the present perfection of methods by which the effective results now achieved in this branch of dental pros- ARTIFICIAL CROWN-WORE. 51 thesis are made possible, is due to the use of cemeuts with which the ends of roots and crowns are hermetically inclosed. Of these the first was zinc oxychlorid, introduced about 1860, though not used in this work till some years later. More important was zinc phosphate, first made known about 1877, while a better under- standing of the properties of gutta-percha as applied to this pur- pose has contributed not a little to the result. Classification of Modern Cro\vn=Work. — Modern artificial crown-work affords extensive facilities for restoring the crowns of natural teeth, and furnishes means of support for bridge-work. The consideration of modern artificial crown-work as presented in succeeding chapters is divided into two general systems, — the porcelain and the gold. Under the porcelain system are included ready-made porcelain crowns, applied with or without collars; and under the gold system, all-gold crowns, gold crowns with porcelain fronts, and special operations. CHAPTER II. Principles Involved in Crown-Work. nomenclature of crown-work — the object of crowning opera- tions — the subject of occlusion— malformed occlusal sur- faces — the post in relation to the canals and roots — the post in relation to post or dowel crowns — short and long crowns — principles governing the construction of root-caps without collars— posts in relation to collar crowns— selection of porcelain teeth— dependence of crown-work operations on asepsis. To systematize and explain the nomenclature used in the de- scriptive details of crown-work, the following definitions of terms used are given : Fig. 56. l 13 13 29 PRINCIPLES INVOLVED IN CROWN-WORK. 53 9. 10. 11. 12. 13. 14. 15. if,. 17. Apex. Cervix. Cervico-palatal surface. Cervico-labial surface. Labial surface. Palatal surface. Incisal end. Occluding, occlusal, or grinding surface. Palatal cusp. Labial or buccal cusp. Sulcus. Root-canal. Surface of end of root. Labial or buccal section of end. Palatal section of end. Post, dowel, pin, or pivot. Point of post. 18. End of post. 19. Cap or plate. (This part when used in connection with a collar is more generally termed the top or plate.) 20. Slot between cap and base of porcelain front. 21. Back of porcelain front. 22. Metallic backing. 23. Metallic backing on incisal sur- face. 24. Post, dowel, pin, or pivot. 25. Base of crown. 26. Collar. 27. Cervical edge of collar or crown. 28. Occluding edge of collar. 29. Cap or occluding or grinding sur- face. Principles Involved in Crown=Work. — The practice of modern crown-work consists in the artificial replacement of the coronal portions of natural teeth affected by or lost from caries, for the purpose of securing a better appearance or greater utility or both. In bridge-work operations it includes also the capping of natural teeth with gold and the artificial restoration of excised natural crowns to be used as supports. No matter what the forms in which teeth and roots are pre- sented for crown-work, invariable mechanical principles govern the application, though the style or method of construction admits of selection. The general condition of the roots or teeth to be operated on, and the character, direction, and force of the occlusion are subjects that govern the application. The location in the mouth and the object of the operation indicate the preferable style or method of construction. Operations on the six front teeth will generally be influenced by appearance, and those on the back teeth principally by utility. The Object of Crowning Operations — In the crowning of roots and pulpless teeth having the coronal section practically de- stroyed by decay, protection against its recurrence and the fracture of the root are the subjects to be specially considered. In cases where sound teeth, or teeth with or without living pulps, only slightly decayed, are to be capped with gold as supports for bridges, the work is to be conducted principally with the view of preserva- tion of the coronal section. Modifying the Occlusion — In a normal state of the occlusion of the teeth the force of mastication is received in an upward out- 54 CROWN-, BRIDGE-, AND PORCELAIN-WORE. ward direction on the palatal and incisal surfaces of the six upper front teeth and inwardly in an opposite direction on the incisal and labial surfaces of the corresponding lower teeth. When bicuspids and molars are evenly occluded the force is direct. In a side or lateral motion of the jaw the force is delivered in corresponding directions against the occluding surfaces of the cusps. This lateral force upon the cusps in mastication is proportionately greater when the cusps are long as in Fig. 57, and it can be modified by giving them the entirely practical but shorter form with shallow sulci, illustrated in Fig. 58. This result can usually be accomplished Fig. 57. Fig. 58. Fig. 59. Fig. 60. without injuriously affecting the appearance, and the work can be materially simplified by a proportionate reduction of the cusps of the natural antagonizing teeth. As the cusps of the bicuspids and molars retain them in proper alignment with their antagonizing teeth, they should always be formed to accord with an outline of the original shape of the natural teeth. Malformed Occluding Surfaces — Fig. 59 shows an upper bi- cuspid crown with a malformed occluding surface of a shape often improperly given in a case of close occlusion. The resultant conditions in time are that the crown and root, because of the gliding pressure exerted on the surface of the crown, are pressed outward so that its stability and usefulness are gradually impaired and finally destroyed. In a case where the symmetry and appearance imperatively demand such an extension of the labial cusps, the displacement just referred to will be pre- vented by giving sufficient length to the palatal cusp to lock the PRINCIPLES INVOLVED IN CROWN-WORK. 55 crown in the act of occlusion, as shown in Fig. 60. This principle may be advantageously applied in construction of crowns for the six front teeth, especially the cuspids, when, owing to the loss of the back teeth, they have to bear the force of occlusion. A slight shoulder or partial cusp will materially lessen the effect of the outward gliding pressure. (See Fig. 70.) Fig. 61. Fig. 62. Adjustment of Incisors and Cuspids. — In the adjustment of incisor and cuspid artificial crowns or teeth the operator should be guided by the fact that the center of the line of the incisal surfaces is always located in the median line of the combined natural crown and root, as is shown in Figs. 61, 62, and 63. Posts in Relation to the Canals and Roots The original forms of the canals and roots- of the teeth should be studied and kept well in mind in reaming the canals for the reception of posts. Fig. 63. Fig. 64. The pulp-canal is located in the central section of each root, in the incisors and cuspids very nearly on a straight line between the end of the root and the center of the incisal edge or cusp. (See Figs. 61, 62, 63, 64, 65.) This fact will materially aid in deter- mining the direction or angle at which a drill, bur, or reamer should be introduced into these teeth. The same principle may be 56 CROWN-, BRIDGE-, AND PORCELAIN-WORK. considered in the conduct of operations on upper bicuspids, lower first bicuspids, the buccal roots of upper first and second molars, and the mesial roots of lower molars, making due allowance for such curve of the root as may exist, should the instrument bo introduced deeply into the canal (Figs. 66, 67, 68, and 69). When the natural crown of a root in normal alignment with the other Fig. 66. teeth has been nearly or entirely lost, the angle to give the instru- ment may be calculated by the adjoining teeth. The reaming should be so conducted that while the necessary enlargement is effected, the root is weakened the least possible. Strength is most required on the approximal sides of the upper and low r er six front roots, as the pressure imparted by the post in the canal is almost entirely received in either an inward or out- Fig. 67. ward direction. Proper reaming of the canal in accordance with its original shape and that of the cervical section of the root, and the forming of the post to correspond, will provide the greatest proportionate amount of strength for both root and post. As the most strength in a post is developed in the line of its greater diameter, a properly adjusted post that inclines to an oval form will afford greater strength than a round one composed of PRINCIPLES INVOLVED IN CROWN-WORK. 57 the same amount of the metal. (Fig. 71 outlines a cuspid root and oval-shaped post.) Tapering the post allows it to be introduced deeper into the canal without excessive reaming than if made of a uniform diameter or only rounded at the point. The point of the post, what- Fig. 68. Fig. 70. Fig. 71. Fig. 69. ever the shape, should be immovably fitted or anchored in the canal, especially when the remaining portion fits loosely, as seen in Fig. 72. Fig. 72. Fig. 73. Fig. 74. Fig. 75. Anchoring the point defines its position and lessens the liability of fracturing the root under pressure. AY hen the point of a post is not anchored, as shown in Fig. 73, and cemented with gutta-percha, crown and post are likely to tilt under continued application of pressure, as seen in Fig. 74. A 58 CKOWN-, BRIDGE-, AND PORCELAIN-WORK. weak or thin post is liable to bend, as illustrated in Fig. 75. Each of these conditions causes fracture of roots carrying post or dowel crowns, or of crowns with very small or improperly applied posts and partial collars. The Post in Relation to Post or Dowel Crowns — A post or dowel crown without a collar is dependent entirely on the post or dowel for attachment and support. In this function the post exerts and resists in its incasement and foundation — the root — all the lateral and direct pressure incident to mastication. The length, shape, and size of a post should therefore be regulated accordingly. A post in a root distributes applied pressure its entire length along the walls of the canal; consequently, in the Fig. 70. Fig. 77. Fig. use of a long post, a proportionately greater area is involved than with a short one. Short and Long Crowns — The greater the distance from the end of the root the force is exerted, the greater the proportion of lateral strain the walls are subjected to. Therefore the shorter the crown, the less is the leverage or pressure. This principle is made clear by Fig. 76. The incisal edge of the crown, which ends at A, will not exert through the post so great a proportion of pressure on the root in mastication as one with an incisal edge at B, which again would exert less pressure than one extended to C. The latter would especially suggest the use of a long post. When the occlusion of the six front teeth is deep and close, as shown in Fig. 77, — a condition termed "close bite,' 5 — the crown PRINCIPLES INVOLVED IN CROWN-WORK. 59 and teeth or crowns as they occlude exert an increasing gliding pressure. An occlusion of this character always demands the longest possible close-fitting canal post. In occlusions occurring nearer the incisal surface, termed "open bite," as seen in Fig. 78, the pressure is more direct and proportionately less lateral in char- acter. Principle Governing the Construction of Root=Caps without Collars. — A cap or plate without a collar, fitted to a flat or slightly curved end of a root, does not afford a positive resistance to lateral pressure in supporting a crown. This resistance, however, can be quite effectually accomplished by giving a deep curve to the sur- face of the end of the root at the labial or palatal side, or both sides combined, — as resistance requirements suggest, — which will be proportioned to the length of the post. The edge of the curve at the gum-margin must come within the line of the segment of a larger circle which passes over the center of the surface of the end of the root, described by the point of the post as its center; or, in other words, the radius or distance from the point of the post to the extreme edge of the curved surface of the side of the end of the root must be shorter than from the point of the post to the center of the line of the orifice of the canal. The shorter the post, the deeper the labial and lingual edges of the curve should extend. The principle is demonstrated in Tig. 79. C is the center of the root-end, D a long post, and E a short one. AA is a segment of a circle described from the point of post E, and BB a similar segment described from D. The beveling or curving of the root should be extended beyond AA for a post like E, and beyond BB for post D. Posts in Relation to Collar Crowns. — In collar crowns, as the root is encompassed by the collar, the principal use of the post is to retain the crown. The actual length and size of post required for a collar crown is dependent on the conditions presented. Deep, substantially fitted collars require the aid of only a moderate post. Xarrow or partial collars when applied to the six front teeth require proportionately larger posts for the crowns, approximating in size to those used for the ordinary post or dowel crown. The force of occlusion being distributed over the entire occlud- 6 gQ CROWN-, BRIDGE-, AND PORCELAIN-WORK. ing surface of bicuspids and molars, when a collar is applied it should entirely encircle the root. Crowns on these roots are therefore not so dependent for security on posts as those placed on the six front teeth. A substantial properly fitted and cemented post in any root-canal, whether or not attached to the artificial crown, always materially strengthens the root. Selection of Artificial Teeth.- — Crown-work is a branch of dental prosthesis which requires judgment and skill in the selec- tion of porcelain teeth for the work in hand, as one of the great objects in dental art should be to conceal art. In a large propor- tion of operations on the front teeth, the result has to be studied more with reference to appearance than utility. In size, form, and shade, porcelain teeth selected for one side of the mouth should match the corresponding tooth or teeth on the other side. The shade should be fully as dark, never lighter. Uniformity in shade of the different teeth should be avoided. Central incisors usually require to be the lightest in shade, laterals slightly darker, the cus- pids darker than the laterals, and the bicuspids about the shade of the laterals. The shades of the lower teeth vary in the same order, but are a little darker. Observation of this rule in selection will avoid that extreme sameness of shade so frequently characteristic of artificial teeth, and cause them to more closely approach natural teeth in appearance. The proper and successful performance of crown-work opera- tions depends largely upon the due observance of the principles here presented. Dependence of Crown=Work Operations on Asepsis Crown-work in the restoration of badly decayed pulpless teeth or roots is intimately associated with their treatment, more especially as regards the establishment and future maintenance of a state of asepsis. The usefulness of operations depends on the successful assurance of this condition. Recent investigations show conclu- sively that ordinarily infection of pulpless teeth and roots occurs from the oral cavity. It is therefore clear that root -canal filling and such restoration of any portion cf the natural crown present as may be required preparatory to capping should be so con- ducted as to offer the greatest possible obstruction to infection. CHAPTER III. The Porcelain Ready-Made Crown System. method of preparation of the root— screw-posts— use of plaster model for fitting crowns— the logan crown— the fellowship crown and the brewster crown— the davis crown — ash's tube teeth and crowns. The porcelain ready-made crowns in use at the present time are the results of progressive development of this branch of the art from what was originally styled the porcelain "pivot-tooth.'' Porcelain ready-made crowns are used by many dentists almost exclusively, excepting only the occasional insertion of a gold cap-crown on. a posterior tooth. The reasons for this are the greater intricacy of the construction of gold crowns and personal objections to crowns with bands or collars. The advocates of the porcelain ready-made crown claim for it natural appearance, restoration of contour, strength, and cleanli- ness, together with simplicity of construction and easy adaptation and attachment to the root, to which the crown is hermetically sealed. Porcelain ready-made crowns at present in use are made in two general styles. In one the end of the pivot, post, pin, or dowel, as it is variously termed, is baked in the porcelain when the crown is made, and the other end cemented into the root when the crown is adjusted. The Logan, Fellowship, and Brew- ster crowns are of this class. In the other style the crown is attached to the root by a pivot, post, or screw, one end of which is cemented in the root and the other in the crown, such as the Davis and Ash. Special advantages are claimed for each of these several forms of crowns. A general knowledge of the different styles is there- fore essential to determine the adaptation of each to the require- ments of a case. Crowns in which the post is to be cemented admit of alignment with the other teeth, in some cases more easily than those which are made with the post in position. The attachment of the crown 01 62 CROWN-, BRIDGE-, AND PORCELAIN-WORE. to the post, however, is not nearly as reliable when cemented as when baked in the porcelain, especially in close "bites." Preparation of the Root=End — The preparation of the end of the root and canals to receive and retain posts is about the same for all of the different styles of ready-made porcelain crowns. The end of the root is trimmed to the gum-margin in the front teeth, slightly below it at the labial side, to hide the intended union of porcelain with root. This may require the removal of the enamel at the cervico-labial section, but not around the entire periphery of the root. The length of the root-canal is measured with a root-canal plugger and its flexible gage. A disk of rubber- dam can be placed on the plugger and used for the same purpose. By this means the proper length for the post is determined. The dimensions of the root determine the diameter. Fill that part of the end of the canal which will not be occupied by the post. Enlarge the canal with Gates-Glidden drill as deep as required to accommodate the post for the crown which is to be inserted. Xext, with a gage-plate, determine the size of the post, and with small-sized fissure-burs gradually ream the canal to a dimen- sion which the post will fit tightly. A post to be inserted in a root to attach, for instance, a Davis or tube crown, is preferably made of iridio-platinum wire. Sere w= Posts. — A size is selected which will accurately fit the hole in the porcelain crown. The surface of the wire should be roughened either by cutting a fine screw-thread with a screw- plate or by rolling the wire under a flat file. The canal should be reamed to accommodate the post. The point of the post beyond the reamed section may be tapered and introduced deep into the canal for security and to strengthen the root in such cases as sug- gest it. The post is cemented in the root with zinc oxychlorid or oxyphosphate. Of the two the oxyphosphate is the more easily manipulated and more reliable for the retention of the post, but otherwise the antiseptic properties of the oxychlorid strongly recommend it. A screw-post screwed into the root is by some given preference to one which is only cemented, and in very short roots can often be used to advantage. The How screw-posts and appliances, illustrated in Figs. 80 to 85, are generally used for the purpose in the following manner: "1. Set gage on a Gates drill (Fig. 80) to one-half the gaged THE PORCELAIN READY-MADE CROWN SYSTEM. 63 depth Fig. SO. of the canal, or further, if the circumstances require it and conditions will safely permit, and drill to that depth. "2. Set the twist-drill in its chuck (Fig. 81) to project the same length as the Gates drill, and drill the root to exactly that depth. Fig. 81. Fig. 82. Fig. 83. Fig. 84. Fig. 85. Fig. 87. "3. Enlarge the mouth of the canal one-sixteenth of an inch deep all around to near the margin of the root, as shown in Fig. 82, using square-end fissure- bur Xo. 59, and then with oval bur Xo. 94, undercut a groove lingually and at the sides. "4. Set the tap in its chuck (Fig. 83) a trifle less in length than the drill, oil it, and carefully tap the root to the gaged depth. "5. Insert the post (Fig. 84) in its chuck (Fig. 85) to the exact gage of the tap, and turn the thumb-screw down hard on the end of the post, then screw the post into the root by hand, release the thumb-screw, unscrew the chuck a half-turn, bend the post until the chuck stands in center line with the adjoining teeth, and unscrew the chuck from the post." The appearance of posts in relation to roots is illustrated in Figs. 86 and 87. In these operations, as likeAvise in others, posts of platinum or iridio-platinum are to be preferred to those made of alloys that contain a large percentage of the baser metals, as the ultimate corrosion of the latter tends to impair the dentin. 04 CROWN-, BRIDGE-, AND PORCELAIN-WORK. Just before a screw-post is screwed into the canal, it is advisable to apply a little of a thin mixture of cement on its surface. Plaster Model to Fit Crown — A plaster model and "bite" of the case will aid in the selection of a suitable crown and in the preliminary fitting to the root. A post of wood or metal placed in and left extending from the root-canal, and then withdrawn in the impression, will give the line of the canal in the plaster model. Exposing the end of the root, by pressing the gum away FlG 8g from it with gutta-percha preliminary to the opera- tion, will greatly assist the operator, by enabling him to avoid accidental lacera- tion of the adjoining mem- branes, and the annoyance attending their bleeding, besides permitting him to carefully study the adjust- ment and cementation of the crown. The obtaining of a close joint is much facilitated in all forms of porcelain crowns by pass- ing a disk of black marking- or impression-paper over the post or pin which is to retain the crown, and placing the crown in position on the root. (See Fig. 88.) Cut the paper in a strip, and, to admit the post, form holes with a punch, as shown on margin of Fig. 88. The points which prevent perfect adjustment are marked on both root and crown, either of which can be dressed off accordingly as seems most desirable. Crowns in which the post is baked in the porcelain will first be described. The Logan Crown. — The Logan crown, now so extensively used, was invented by Dr. ]VI. L. Logan. Its distinctive features are the cupping out of the base surrounding the strong platinum post, the form of the post, and the baking of the post in the porce- lain. As originally made the post was round, but shortly after the tapered I-beam post was introduced. At first the I-beam post was plain (Fig. 89), and it was nicked or serrated across the flanges by the dentist when mounting the crown. The present form, with THE I'ORCELAIX READY-MADE GROWN SYSTEM. 65 a continuous double flange and transverse ribs, is shown in Figs. 90, 91, 92, 93, and 94. The larger end is baked in the porcelain, the flanges and ribs affording a very strong hold. The cupped-out base permits the use of a larger body of cement in setting, and the ribs give the cement a hold similar to that of the porcelain, the whole forming an ideally secure mounting. Fig. 89. Fig. 00. Fig. 01. Fig. 02. n Fig. 93. Fig. 95. Original form of the Logan Crown. Fig. 96. Fig. 94. Fig. 97. Set of six front upper crowns, natural size. The cupping out of the base also gives a great advantage in fitting the crown, as the comparatively narrow rim is ground away with but little labor and no risk of marring or destroying the post in the process. Mounting. — In the preparation of a root for a Logan crown the root-canal is enlarged and so shaped that the post if possible, at least at its point, shall fit tightly. This is best done by first using the Gates-Glidden drill and then enlarging the canal to the proper form and size with a root-canal reamer (Figs. 95 and 96). 66 CBOWN-, BRIDGE-, AND PORCELAIN-WORK. The root surface at its labial side is preferably trimmed with suitably shaped corundum-points or wheels, or with a root-facer Fig. 98. Fig. 99. Fig. 100. Enlarged sec- tional view of a left central in- cisor root with anchor-post in position. (Figs. 97 and 98), so as to give it a labial slope, which will permit the lapping of the labial face of the crown at the cervical border over the face of the root and effect an artistic as well as a desirable Fig. 102. Fig. 103. form of joint under the gum-margin. As the root-canal is being reamed the post of the crown is to be frequently inserted (Fig. 99) to determine the fit (Fig. 100) and proper alignment of the THE PORCELAIX READY-MADE CROWN SYSTEM. 67 crown. When the base of the crown touches the end of the root, points of contact that interfere with an accurate adaptation should be removed. This can be effected by trimming either the surface of the root or the base of the porcelain crown. When the root or porcelain requires to be extensively removed, it is generally best done with a safe-side wheel, such as is shown in Figs. 101 and 102, to avoid injury to adjoining teeth or the post. At this stage of the fitting the use of a disk of articulating paper (Fig. 88), as already explained, will simplify and facilitate the operation. Fig. 103 illustrates a properly fitted Logan crown. For short or small roots the post of a Logan crown should be proportionately reduced in length or size. For bifurcated bicus- pid roots the post can be bent as shown in Fig. 104. Fig. 105 Fig. 104. Fig. 105. Fig. 106. Fig. 107. illustrates the best manner of bending the post. A preferable method to practice in some cases, that of splitting the post, is ex- hibited in Figs. 106 and 107. Zinc oxyphosphate or gutta-percha, or the two combined, are used to cement the Logan and similar styles of ready-made porce- lain crowns. Method of Fitting Logan Crown by Model of Natural Tooth. First prepare the face of the root to be crowned as desired (A, Fig. 108), and having selected a suitable crown, B, bend the pin, if necessary, so as to make a proper alignment. Next place a piece of sheet wax around the pin next to the porcelain. C, then take ISTo. 60 tin foil and trim a disk 3 68 GROWN-, BRIDGE-, AND PORCELAIN-WORK. little larger than the abutment, D, pierce the center of the disk with the crown pin or instrument shown in the margin, E, pushing the disk down until it touches the wax; place the crown on the root and force it to place, F, the wax driving the tin-foil disk to a perfect apposition with the abutment of the root. Remove the crown with the wax, holding the tin-foil disk in posi- tion, and with a pair of sharp-pointed scissors snip the edges of the disk slightly all around. Place a small pellet of wax on the point of the pin, H, then insert the pin up to the porcelain in quick-setting plaster, I; after the plaster hard- ens warm the crown and remove it, the snipped edges of the disk serv- ing to hold it in position; clean off the wax and replace the crown on the model, and you have a perfect metallic-surfaced model of the abutment of the root to which to grind with a perfect view of every surface of the root, the wax which was on the end of the pin allowing it to penetrate the plaster as the porcelain is ground away. By this method a Logan crown can easily be made to fit perfectly. THE PORCELAIN READY-MADE CRO^Y^ 7 SYSTEM. QQ The Fellowship Crown and the Brewster Crown. The Fellowship crown (Fig. 109) and the Brewster crown (Fig. 110) are crowns with fixed posts. The posts are made of a German silver alloy, which, after the crowns have been baked, are attached by another baking with a low-fusing porcelain. The post Fig. lOfl. Fig. 110. of the Fellowship is additionally secured by a piece of wire, which passes laterally through a perforation in the post and base of the crown. The application of these crowns is very Fig. ill. . .. .. , ^ ^ T similar to that of the Logan crown. The Davis Crown. This form of crown (Fig. Ill) has a cavity ex- tending into the base of the crown, the orifice of which is reamed. The dowel-pin, which is made of German silver, has a shoulder or rim near the end. The end of the pin fits in the cavity of the crown and the rim in the reamed section. When the crown and dowel-pin have been propefrly fitted to the root, if oxyphosphate is the cement to be used, post and crown may be cemented in position simultane- ously. If gutta-percha is preferred for the root-canal, the dowel- pin is first cemented in the crown with oxyphosphate, and after it has set the pin is fixed in the root with the gutta-percha. 70 CROWN-, BRIDGE-, AND PORCELAIN-WORK. Ash's Tube Teeth and Crowns. These teeth have a perforation through the center, with a thin platinum tube baked in the porcelain. They are supported on the Fig. 112. Fig. 113. Fig. 114. root ^7 tne ^ ute ^ P ost > shown in Fig. 113. When the crown is properly ground, the base is to be countersunk sufficiently to receive the shoulder of the pin. The pin is then bent so as to allow the crown to assume its proper position on the root. The socket-han- dle instrument, shown in Tig. 120, is the most suitable for this purpose. The attachment of the crown is made by first securing the pin in the crown with sulfur or soft solder and then cementing the fluted post in the root-canal with either gutta-percha or oxy- Fig. 115. P hoS P hate - Tigs. 116, 117, 118, 119, 120, and 121 illustrate Ash's dowel crowns. They are applied in a manner similar to the Davis crown. The dowels or posts are made of what is termed "Dental Alloy," and are strongest at the part to bear the greatest strain, the portion where the crown joins the root. Fig. 116. Fig. 117. Fig. 118. Fig. 119. Fig. 120. Fig. 121. THE PORCELAIN READY-MADE CROWX SYSTEM. fl Remarks on the Use of Porcelain Ready-Made Crowns and Crowns without Collars. Porcelain ready-made crowns have some decided advantages. They are especially useful in many cases where an inexpensive or easily adjusted crown is required, or where some pathological con- dition limits the probable durability or permanence of any opera- tion. In the insertion of porcelain crowns, the removal of the whole or a part of the natural crown, which could be utilized to some extent as a foundation by other systems, has given rise to various objections. If the natural crown is entirely cut away the pin, or post, upon which almost the entire support of the artificial crown is thrown, exerts great leverage in the root-canal when no band or brace is present on the exterior of the root to relieve the strain. With the whole force of mastication bearing directly upon these pulpless roots, whose disintegration is slowly but constantly progressing, the inevitable result can well be conjectured. Sooner or later they are fractured, and their usefulness as a foundation ended. These facts, and the lack of strength incident to some forms of construction, are the principal objections urged against porcelain crowns as ordinarily inserted. Crowns in which the post is cemented in the porcelain are less suitable for close bites than those stvles in which it is baked in. CHAP TEE IV. Porcelain Crowns with Vulcanite Attachment — A Temporary Crown. Fig. 122. Fig. 122 illustrates a porcelain crown with vulcanite attachment. The prepared root extends at the palatal side a little below the gum line (A) at the point B. A plate tooth (C) is ground and fitted to the root. An iridio- platinum post is then fitted to the root, flattened slightly and bent at D, and riveted to the tooth. The proper alignments of the tooth and post to the root are then obtained, and they are invested and the post soldered and strengthened at the point D. The backing is then grooved and notched slightly, wax applied, the crown ad- justed to the root, and the wax shaped so as to form a foundation and overlapping edge at the palatal portion (E), and also extend around the post up the canal. The crown is next removed, invested in a flask, packed with rubber, and vulcanized. In trimming and finishing, the rubber may be allowed to form a partial band or collar around the palatal portion of the root, where it will not show. It is then cemented on to the root with oxyphosphate. A Temporary Crown. — Fit in the root-canal a post of metal, preferably made of German silver wire. Let the post extend out of the canal about one-eighth of an inch and roughen the sides. Perforate a disk of the heaviest pattern tin or 1/1000 plati- num foil with the post, and fit to the end of the root. Fit a suit- able two-pin vulcanite porcelain tooth to the disk. Groove out the porcelain, if necessary, to fit over the post. "Wax the porcelain tooth to the disk and post, remove, and invest in plain plaster of Paris. Remove the wax with boiling water, and apply a little muriate of tin to the end of the post. In the place of the wax, flow fusible metal, which melts at not less than 200 degrees, or tin 72 PORCELAIN CROWNS WITH VULCANITE ATTACHMENT. 73 solder, if gutta-percha is to be used to cement the crown, and instantly press down firmly into the investment with a napkin over the finger; cool, remove, trim, and cement on the root with gutta-percha that softens at a low heat. CHAPTER V. Gold Collar Crowns. construction and adaptation of collars— methods of measure- ment—fitting of collars to root or crown— application of a local anesthetic— collar crowns hygienically con- SIDERED. This style of gold crown includes those methods which consist in banding, capping, and hermetically inclosing with gold the end or the neck of a root, with or without any portion of a natural crown, for the purpose of securing stability to the artificial crown, preventing fracture of the root and decay of the parts. This method possesses much practical value as a preserver of tooth- structure and restorer of usefulness to the teeth, and affords excel- lent supports for bridge-work. Collar crowns, the use of which has become quite general, have been described by many writers in the past. Dr. William H. Dwindle relates the application of the method to a crown with a porcelain front, 1 and Drs. W. 1ST. Morrison 2 and J. B. Beers 3 tell of it in the construction of all-gold cap-crowns, showing its use fifty or more years ago. 4 Collar crowns of which the part that essentially constitutes the cap is constructed in sections, will be first described. The Construction and Adaptation of Collars. Careful study of the different forms of crowns and roots, and of the anatomical structure and relationship of the contiguous parts, is most essential for the perfection of construction and adap- tation required in collars, bands, or ferrules, as they are variously designated. 1 American Journal of Dental Science, April, 1855. 2 Missouri Dental Journal, May, 1S69. 3 Circular to dental profession, 1873. 4 J. Patterson Clark, 1836. 74 GOLD COLLAR CROWNS. 75 Fig. 123. Fig. 124. Fig. 125. Many devices and methods in use facilitate this operation, but its skilful performance can only be attained by study and practice, as is proved by the easy and perfect manner in which it is done by experts in crown- and bridge-work, who use no appliances but pliers and shears guided by an intuitive per- ception of the requirements of each case. The collar is preferably made of 22- to 23-carat gold plate; the tendency now is to use a softer alloy of plate than formerly. Pure gold plate lined with platinum is also used, and platinum 1 plate in special cases. Gold plate of No. 28 to No. 30, or gold and platinum about No. 30, U. S. standard gage, 2 affords the requisite strength, to- gether with easy adaptation to the form of the crown or root. The size of the cer- vix of the root or dimension of the natural crown to be capped, and whether it is to effect only restoration of the crown or to also give support to bridge-work, should govern the choice of the gage of plate to be used. Cuspids and molars require a heavier plate than small laterals or lower incisors, and in all forms of gold caps the gage should be increased when they are to sup- port bridge-work. The natural crown or root having pre- viously been properly prepared (see page 34), a strip of the metal is cut of the length required, and generally from one-fourth to one-half of an inch in width (Fig. 123). The end to underlap at joint is beveled with a file (A, Fig. 124). The strip is then bent 1 The use of platinum plate. No. 32 to 34 gage, is specially recommended to students, as collars formed of this metal are not apt to be melted in any of the soldering processes. If very thin platinum is used, pure gold can be flowed over the outer surface after it is adapted to the cervix, to stiffen it. A little dampened fine marble-dust or whiting should be placed on the inner surface of the collar during the operation to prevent intrusion of the gold on that part. This method is excellent when a small, narrow collar is required for an incisor crown which is difficult to adjust to the form of the root. 2 U. S. standard gage is the gage always referred to in this book. C5 7g CROWN-, BRIDGE-, AND PORCELAIN-WORK. with suitable pliers (Fig. 125) to the average form (Fig. 126), any special deviation from such average being noted (Fig. 127), and to the size of the cervical periphery of the root of the tooth to be crowned. The edge toward Fig. 126. , & , , the gum may also be ^ (j f~") ~ trimmed, so that it will in (\_V> kJJj a mea sure approximate in C \_ 7 ) shape the curve of the rnar- /-~^>-' ^^~^ S m °^ tue S um - -ft * s tiien J^-O *-— ""' placed on the root and \^~2) adapted as closely as possi- ble to its form, with the upper edge of the metal pressing gently under the \"^ V^"^ / free edge of any portion of ^__y * -^ the gum it may meet. It \" V V' y^^ j is then removed and cut so ^- — ' ^ as to allow the ends to lap over slightly. The adapta- tion to the root is then continued, during which process the metal should be clamped at the joint, heated, and chilled in water after each trial, in order to -C ) maintain the shape given -0\ t0 ti- At the last adjust- ment to the root, the lap- over is marked on the metal with a sharp-pointed instrument, the collar is The palatal side of the superior molars, in many removed, and the edges cases, is of the large oval form indicated br the outer } U £ M together line to the form of the first molar. The small spurs o _ J o indicate the points generally found the most suitable flush 01* a little over the tomaketh e .ioi..t. mark The joint ismade by placing in the seam the least possible quantity of solder, or, better still, of fluxed solder filings, and holding the collar with a clamp in a blue (Bunsen) gas flame while the solder is fused. Another method frequently adopted is to grasp the seam at the cervical side of the collar with the points of a clamp such as is shown GOLD COLLAR CROWNS. i i Fig. 127. in Fig. 193, or, better, with soldering-pliers (Fig. 128), or, ordinary solder-tweezers held in a vise (Fig. 129), and unite the seam only at the extreme outer end with an atom of solder fused with a blowpipe. The points of the clamp or tweezers prevent the solder from flowing along the joint. The cervical side of the collar is left open by this method of procedure, which permits the collar to be slightly contracted, if desired, then the solder can be flowed across the collar. The collar is next slipped over the point of a small anvil, and the joint tapped and trimmed level. Methods of Measurement. — The root is encir- cled with a strip of thin sheet copper, about Xo. 31 gage, previously annealed, one-sixteenth of an inch or less in width, and the copper fitted to the cervix. Fig. 129. crb Fig. 128. It is removed, and cut so there will be a slight lap- over of the ends on the root, then again fitted to the root, and the position of the lap-over end marked on the copper. This little strip of copper, which, being soft and flexible, can be most accurately fitted to the root without inconvenience to the patient, when re- moved shows the exact length and shape to cut the gold or platinum for the collar. The copper pattern is laid upon a strip of the metal from which the collar is to be formed, from one- quarter to one-half inch in width, and the exact length required is marked, and the metal is then cut a trifle longer than the mark indicates (less than one-sixteenth of an inch), to allow for an overlap joint. It is then bent and the ends brought together, the outer end placed even or 7S CROWN-, BRIDGE-, AND PORCELAIN-WORE. flush with the mark, and soldered as above described. The collar is next bent to the shape of the root, when it is ready to be ad- Fig. 131. Fig. 132. % justed. This method is simple and practical, and also economical, as it accurately defines the amount of plate required. To measure with a wire: Form a loop of copper wire, about 30 gage, by twisting the ends together with pliers. Slip the loop over the tooth or root, press the wire down under the gum-margin, Fig. 133. Fig. 134. Fig. 135. and twist the ends with the pliers until the loop fits tightly at every point (Figs. 130 and 131). Slip off the loop, cut it in the center, and extend the ends length- wise in opposite directions, as shown in Fig. 132. Then lay it on the surface of the plate of which the collar is to be constructed, and mark the length. Cut the metal beyond this mark sufficiently to allow for an overlap; bevel and lap the ends to the mark and solder them. A dentimeter, such as is exhibited in Fig. 135, greatly facili- tates measurements with wire. The ends of the wire are passed into the hole in the face of the head, and out through the openings which are cut into it from two sides. The loop thus formed is adjusted around the tooth or root, the end of the den- GOLD COLLAR CROWNS. 79 timeter is pressed against the root at the gum-margin, the loop pulled tight, and the ends of the wires wound around the boss on the handle. A few turns of the dentimeter twist the loop tight, when the wires can be unwound from the boss, the dentimeter laid aside, and the loop removed. "When a mandrel is used in forming a collar, the size or shape is first taken with a wire. The wire ring is then carefully removed, laid on a piece of air-chamber tin, a piece of flat iron put over it, and with a blow from a hammer on the iron the wire is driven into the tin (Fig. 133). It is next extricated from the tin, slipped on a mandrel that represents the form of the root to be crowned, and pressed down gently as far as it will go without stretching the wire (A, Fig. 134). The distance from the end of the mandrel to the wire is then measured and marked on a strip of paper, and Fig. 136. Fig. 137. Fig. 138. the wire removed. The gold to form the collar is then bent and shaped on the mandrel, with the edge which is to form the cervical portion (B) placed a little below the line of the wire (A), as shown by the measure- ment previously taken. The ends of the gold are beveled, slightly lapped, and the edge of the lap-over marked (C) and soldered. The collar is then shaped to the form given by the wire in the tin, after which it is ready for adjustment in the mouth. Fitting of Collar to Root or Crown. — When the collar has been formed, it is adjusted on the root and pressed or, with the aid of a piece of wood placed across its outer edges, gently tapped up 80 CROWN-, BRIDGE-, AND PORCELAIN-WORK. to the margin of the gum. A line parallel with the margin is marked with a sharp-pointed instrument on the collar (A, Figs. 136 and 137), which is then removed, trimmed to this mark, read- justed, and again marked (B), and the process continued until the collar fits proportionately under the margin of the gum. If this part of the operation is skilfully performed, and the collar is not forced into the investing membrane of the root, very little pain will be caused the patient. If, on adjusting, a collar is found a trifle too small, it is easily enlarged by tapping with a riveting hammer on an anvil (Fig. 138) at the edge-end of the collar marked B, Fig. 124. By this means the surplus gold at this point can be thrown into the collar and its circumference proportionately enlarged without altering its gage. If, on the contrary, the collar should prove to be too large Fig. 139. in circumference, the difficulty can be remedied by slitting the gold nearly but not entirely across the side opposite the joint, bevel- ing and lapping the edges slightly, soldering, and trimming. The edge is then burnished to the periphery of the root. For the pur- pose of fitting collars a set of burnishers should be used especially formed to suit the different positions and avoid irritation of the margin of the gum. (See Fig. 139.) Finely serrated foot-shaped gold-foil condensers can be advantageously used to flatten an edge or a stiff or angular point of a collar. Application of a Local Anesthetic. — The application of a local anesthetic, such as cocain, will lessen pain attending the adaptation of a collar under the gum-margin. Cocain is very effective in the form of a saturated solution in glycerin. The parts should be surrounded with a napkin, or with bibulous paper, and dried. GOLD COLLAR CROWNS. 81 Then a drop of the solution is placed on a slab, and a little at a time is carried on the edge of a thin burnisher and applied well up under and around the free margin of the gum of the tooth operated on. When this has been done, some of the excess of the solution, which will usually be found at the cervix, may be rubbed on the labial and palatal sides of the gum. The patient should be directed not to swallow the saliva during and for some time after the application of the cocain. The anesthetic effect pro- duced by this method will usually be found sufficient to partly or entirely divest the operation of pain, and of such duration as to seldom require repetition except at subsequent stages of the operation. Electrolysis (cataphoresis) will effect rapid diffusion of the cocain, the solution of cocain being placed on cotton against the sides and margins of the gums. A weak current of electricity should be used, the positive pole being applied to the cotton and the negative pole to the cheek or held in the hand of the patient. The time the method requires is the objection to its use. Collar Crowns Hygienically Considered. The principal argument against collared or ferruled crowns is that they are productive of irritation to the peridental mem- brane, ultimately causing its absorption and the exposure of the collar. This would be theoretically and practically true of a rough or porous substance encircling the root, or of an imper- fectly and unskilfully adjusted or cemented ferrule or collar, which would by its presence hold a position analogous to a cal- careous deposit; but it could not be fairly predicated concerning a perfectly fitted collar, forming at its edge a smooth and im- perceptible union with the sides of the root, and presenting a uniform and benign surface to the investing membrane. In the case of perfectly adapted collars, when any irritation of the mem- brane exists, it will be found to result from such causes as usually produce it when the natural crowns are present, namely, dental concretions. A tarnished and unclean condition of the surface of the gold of the collar will produce irritation of the membranes, which is a matter independent of the collar itself, and easily reme- died by cleansing and polishing the surface. Where an acid condi- tion of the secretions of the mouth exists, a collar of platinum is 82 CROWN-, BRIDGE-, AND PORCELAIN-WORK. suggested in preference to gold, as this metal will not be affected, but will constantly present an untarnished surface. When evidences of a tendency to pyorrhea alveolaris exist, a collar adjusted to support bridge-work should not be extended under the gum-margin ; instead the edge is best placed considerably above the gum-margin, so as to better permit treatment of the disease. CHAPTER VI. Gold Collar Crowns with Porcelain Fronts. incisors and cuspids: constriction and adaptation of the cap— the post— method of forming posts to accurately fit canals— post and cap— selection and adaptation of porce- lain front — protecting the incisal edge— backing the porcelain front — preparation for investment— soldering and finishing bicuspids and molars— dr. stowell's method of applying a countersunk tooth or a logan crown- crowning in cases of abrasion— gold crowns with porce- lain fronts for teeth with living pulps. This style of crown for incisors and cuspids, as originally made by Dr. C. M. Richmond, and with which his name has become associated, consisted of a cap for the root, formed of a band of gold capped with platinum, on which was soldered a tooth with a slot in the center between the pins. Through this slot and the center of the cap a screw passed, which entered into a cylinder previously screwed and cemented into the root-canal. The form of gold collar crown in general use is, in principle, the same as what was formerly known in dentistry as a gold pivot- tooth, with the addition of a gold collar for the root, and having the advantage of oxyphosphate for its cementation. These im- provements enhance its value as a crown, and materially change the process of its construction. Adjustment of the Collar. — In making an incisor or cuspid crown of this style, the root-canal is treated, the root shaped, and a collar made and fitted as described in the preceding chapter. The collar is held in position on the root, a sharp-pointed instru- ment introduced inside of the collar, and the line of the surface of the root scratched on the metal around the circumference. The collar is removed and trimmed a trifle flush to this mark with small- pointed shears (Fig. 140). It is adjusted on the root, and the edge of collar and root ground even, removing some of the surface of the root if necessary for this purpose. In the operation of 83 84 CROWN-, BRIDGE-, AND PORCELAIN-WORK. Fig. 140. grinding, the collar should be first firmly held in position on the root at the labial side while the palatal section is ground, then at the palatal while the labial is being reduced. At the labial section, the collar and surface of the root should be removed, so as to be invisible if the patient exposes the gum-margin in speaking or laughing. In cases where there is no such exposure, a proportionate amount more of the collar and root may re- main; this is often desirable, as it af- fords additional strength. The work will then present an appearance re- specting the collar such as is shown in Fig. 141 and at A, Fig. 145. As the sides of the collar are parallel with the line of the cervical section of the root, the edge of the collar at the palatal side forms a right angle with the surface of the end of the root (A, Fig. 141). In close occlusions this is liable to give a shape to the fin- ished crown at that part quite percept- ible and objectionable to the patient. This can be avoided by slightly round- ing off the palatal edge of the root to the form illustrated at B, Fig. 142. The collar is then slit two-thirds across, as outlined at S, Fig. 142, the edges beveled slightly, lapped, fitted on the root, pressed and burnished to the part, and soldered. In the finished crown the collar will then present a form nearer that of the natural tooth, as illustrated in Fig. 143. The top of the collar that completes the cap is made of very thin platinum plate, about No. 37 gage or 1/1000 foil. The foil is preferable when it is desirable to have the least possible space occupied by the platinum at the labial section of the cap. Thin platinum forming the top to the cap does not materially affect the strength of the finished crown, as that part is reinforced by the solder subsequently applied. GOLD COLLAR CROWNS ^YITH PORCELAIN FRONTS. 85 To Form the Cap to the Collar — A piece of the platinum is cut, square or round, considerably larger than the circumference of the collar. The outer edge of the collar is placed against the plati- num and adapted to its surface by slight pressure between the fin- gers. With the collar so placed the edge of the platinum is seized with a clamp. A piece of solder, with flux, is placed on the platinum outside of the collar and against or touching it. The whole is then held in the flame of a Bunsen burner, the solder fused, and collar and top united (Fig. 144). The quantity of solder applied must be very small, barely sufficient to unite the parts. So limited, it will not flow over the inside of the cap to interfere with its fit on the root. All parts of the edge of the collar and platinum should touch Fig. 141. Fig. 142. Fig. 143. Fig. 144. before they are soldered, otherwise in subsequent soldering the seam is liable to open up. Perfection in this part of the work is most easily attained by first attaching the platinum to the edge of the collar at one point with a mere particle of solder, to retain and position it, and then readapting the rest of the edge and completing the soldering. When the collar and top are united, the plati- num is trimmed to the outline of the collar with small shears, and finished smooth with a corundum-point. The cap is next adjusted on the root. Should any part of the cap not seem to go to its position accurately, a little pressure with a foot-shaped foil condenser along the edge of the collar at the part soldered to the top will correct it, if the soldering has been properly conducted. Pressure is next exerted with the finger on the palatal side of the cap to retain it in position while the labial section is burnished to the flat surface of the root. This adaptation 86 CROWN-, BRIDGE-, AND PORCELAIN-WORK. of the platinum steadies and positions the cap on the root. The cap is then ready to receive the post. Preparation of Canal to Receive Post. — In a collar crown of the style described, the collar is largely relied upon for reten- tion on the root, and the post is therefore not usually as impor- tant a part as in a crown where a partial collar or no collar is used. To receive the post, the root-canal is first reamed with a Gates-Glid- den drill and then with suitable sized fissure or round burs (B, Fig. 145). The orifice to the canal should 4 be slightly enlarged with a large, round bur, to give it a slightly cup-shape form. Into this depression the platinum of the cap to the collar is to be burnished. The object of the depression is to provide a space to flow the solder in around the post to reliably attach it to the cap, especially should conditions require that the end of the post be ground off close to its surface. (See Fig. 146 Fig. 146. in section.) Posts. — Platinum or iridio-platinumwire, preferably round, ISTos. 16 to 18 gage — a little smaller for laterals or other roots which require its reduction — is used for posts. A hollow post, the open space in the center of which is small, affords the advantage that it can be drilled out of the canal in a compara- tively easy manner if for any reason it becomes necessary to re- move the crown, as the drill will follow the fine opening in the center of the wire. 1 The use of posts made of alloys of the base metals is to be condemned for this style of work. The wire may be first rolled under a flat file, to roughen its surface. It should be slightly tapered and introduced one-quarter of an inch, more or less, up the canal, as indicated by the conditions of the case (Figs. 145 and 147) respecting length of root, size of artificial crown to be mounted, and character of the occlusion. A long, large crown or a close occlusion suggests a longer and heavier post than a small crown or a more favorable occlusion. If the canal is for any reason much enlarged, the point of the post should be tapered and extended to its extremity in order to strengthen the root as well as anchor the crown. (See Part I, Chapter II.) When 1 Hollow posts are now manufactured and sold. GOLD COLLAR CROWS S WITH FORCE LAIS FROSTS. 87 gutta-percha is the cement to be used to attach the crown, a longer post is required than for oxyphosphate. The post should fit the canal in such a manner as to need the presence of only a small quantity of the gutta-percha to secure it (Fig. 147). Method of Forming Posts to Accurately Fit Canals. — To form a post which will accurately fit a canal, especially canals which for some reason are considerably enlarged, slightly taper the point of a piece of platinum wire about No. 20 to 21 gage and a half -inch long. Fit it to the extremity of the canal and bend the end of the wire toward the labial side at a right angle, to indi- cate its position when inserted (Fig. 148) ; tip the point of the wire with pure gold by fusing on it a pellet of gold foil. Cut a strip of platinum foil 1/1000 gage about one-eighth of an inch wide and Fig. 147. Fig. 148. Fig. 149. A B an inch in length, bend the end of the strip of foil over the end of the wire close to the point, and solder the wire and foil in a Bunsen flame. The tip of gold at the point of the wire on fusing will attach the strip (A, Fig. 149). Xext wind the strip around the wire, as shown at B, Fig. 149, and insert in the canal. The folds of foil will press down on the wire in conformity to the size and shape of the canal, as illustrated at C, Fig. 149. Seize the exposed portion of the foil and wire firmly with small-pointed pliers, re- move in position, and solder in a Bunsen flame with pellets of gold foil. Apply only enough gold to unite the layers of platinum, for if an excess be used the shape of the post will be altered and it will not fit the canal. The corrugations on the post formed by the layers of platinum foil afford an attachment for the cement. Post and Cap. — The post having been formed, the cap is ad- gg CROWN-, BRIDGE-, AND PORCELAIN-WORK. justed on the root, the platinum over the canal is burnished into the orifice and punctured. The end of the post is seized between the points of wire pliers and the post inserted and forced to posi- tion in the canal and the correctness of its relations with the cap observed and decided. Cap and post are next removed, both dried, slightly heated, and the surface of the cap and extreme end of the post veneered with adhesive wax. The cap and post are again ad- justed to position on the root, a small pellet of the wax is placed over the end of the post and pressed against the surface of the cap and around the post. The wax is chilled with water and the cap and post carefully removed and invested. The investment mate- rial should be carefully flowed into the interior of the cap, so as to fill every crevice. When set, the investment is trimmed and reduced to as small a size as permissible (Fig. 150). It is next heated and solder flowed into the depression about the post flush with the surface of the cap. Should any extensive aperture exist in the platinum around the post at the orifice of the canal before solder- ing, a pellet of gold foil may be gently pressed in the place to aid /the solder to cover the part. After removal from the investment and boiling in acid, the cap and post are adjusted in position on the root. Selection and Adaptation of the Porcelain Front. — The adap- tation of the porcelain front to the cap is next made, either directly in the mouth, or by the aid of a model of the case. When a model is to be used, a bite in wax with the cap in position is first taken and afterward an impression with impression-compound, or prefer- ably plaster, which will remove the cap in position and include the adjacent teeth, especially the opposite corresponding tooth to that being crowned, if present. To permit easy removal of the cap from the model, if the crown is to be fitted in the mouth during its construction, a little wax should be placed with a heated spatula around on the inner surface of the collar and the sides of the post also be slightly veneered with it. A plaster model is made, and the wax bite having been adjusted on it, an articulating model is also made. The projecting end of the post is next cut off a little above the surface of the cap with a thin disk or cutting pliers. The end of the post is then reduced with a corundum-wheel close to the sur- face at the labial side, but left slightly projecting above it at the GOLD COLLAR CROTVSS "WITH PORCELAIN FRONTS. 89 palatal for additional strength should such a form offer no ob- struction to the setting of the porcelain front (Fig. 151). The porcelain front is formed of a cross-pin tooth. The shade selected should be at least as dark as that of the opposite corre- sponding natural tooth, if present, or, if absent, that of the adjoining- teeth. The general form, while suitable in appearance, should lie such as will permit of proper adaptation without ex- p IG 151. cessive reduction by grinding. The curve of the sides toward the base should be such that when the front is ground, the base shall not greatly ex- ceed in width the surface of the cap, and the pins be located so that their strength shall not become impaired in the required removal of the porcelain for the proper adjustment of the front. There are two methods of setting the porcelain front to the cap. In the first method the front is ground to position with the base of the porcelain closely fitted to the surface of the cap (Fig. 152). The palatal surface and incisal edge of the front are then backed with metal, invested, and soldered to the cap. In the second method, which is preferable, the front is fitted at the cervico-labial section to rest on the cap, while the remainder of the base is ground so as to form a slightly increasing space toward the palatal side ju-t over the post (B, Fig. 151). The cervico-labial vdge of the porcelain front should be placed even or full with the edge of the collar. As the porcelain rests 011 the cap at only one point, it simplifies the work of correctly positioning the front with the other teeth. This space between porcelain and cap can subse- quently be uniformly filled with the solder and greater continuity of structure obtained than by the first method. If a model is used, although it facilitates the operation of fitting, the exact alignment of the front had best be determined by adjustment in the mouth. To Protect the Incisal Edge of the Porcelain Front. — To pro- tect the incisal edge of the porcelain front against fracture in such way that the gold shall be invisible, the porcelain should be ground and beveled off to the incisal edge at a proper distance from the pins, as shown in Figs. 151 and 152; also at A, Fig. 153. In the final finishing the gold is brought on a straight line, or nearly so, with the edge of the porcelain, as shown at B, Fig. 153. By tin* 90 CROWN-, BRIDGE-, A*W PORCELAIN-WORK. Fig. 153. f^i&s^ B plan the porcelain is protected and the gold is rendered invisible when viewed from the front. Backing the Porcelain Front. — The backing of the porcelain front should fit the porcelain closely and furnish the greatest pos- sible strength to the finished crown. It is made of platinum or gold. Platinum im- parts a slightly blue, and gold a yellow shade to the porcelain. The best platinum for the purpose is in the form of foil 1/1000 gage, as such a thickness permits \ ^^^y * ne metal to be closely adjusted to the sur- face of the porcelain. The front is first divested of every par- ticle of wax, — best done by immersing it in boiling water. The platinum is applied to extend in one piece over the back of the front down on the base as far as possible between the porcelain and the top of the cap without interfering with the posi- tioning of the front. The ends of the pins are first pressed against the platinum and its surface indented. Holes are punched through the indentations and the platinum closely adapted to the surface of back and base (B, Fig. 151) to carry the solder and fill the space between the porcelain and cap. The platinum is next trimmed off even with the edge of the porce- lain, except at the incisal section, where it is cut even with the back of the front at the line C, Fig. 151 giving the backing when off the front the form shown at D. The incisal section and only the back of the front is then additionally backed with a piece of 22-carat gold plate, or of platinum and gold, about INTo. 30 gage. Holes for the pins are punched and countersunk in the plate, which is cut and fitted the width of the front and only long enough to extend past the pins, and to cover and extend slightly beyond the edge of the incisal sur- face. The gold will then present a form such as is shown at E, Fig. 151. Two or three holes are punched from the inner side of the hacking outward above the pins, as shown at E, Fig. 154, to enable the solder to easily enter and Fig. 154. GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. Q\ flow between the backings. The platinum foil backing having been closely adjusted to the surface of the porcelain, the gold backing is placed over it and the pins bent down on the surface in either of the positions shown at A and B, Fig. 155. When bent as at A, they assist in retaining the solder in position in soldering and thickening the backing at that point, if that is desirable. When the first or inside backing is preferably formed of pure gold instead of platinum foil, it is applied in the same manner as the platinum, but must be of about No. 37 gage. Platinum-lined gold nearly as thin as platinum can be used instead of pure gold, with which, by placing the gold side toward the porcelain, the same effect on the shade can be obtained as with 'pure gold. Other methods of backing are in use. Of these, one which may be advantageously practiced, espe- cially when the back of the porcelain front is ground quite short, is: First back the front and reinforce the incisal section with pure gold plate in one piece of about No. 30 to 32 gage. Next cover the base with platinum foil of at least 1/2000 gage by heat- ing the porcelain, varnishing the base with adhesive wax, and press- ing the foil on the surface. By again heating the front and foil and by exerting uniform pressure over the entire surface with a napkin or a pellet of cotton, the foil will be closely cemented against the surface of the porcelain and the intervening varnish of wax imperceptible. The surplus foil is trimmed off close to the edge of the base of the front. Another method is to first back with either platinum or gold plate of No. 30 to 32 gage only the palatal side of the front, apply the thin platinum foil to the base, and as the crown is ready for investment, place and cement in position with wax a piece of 22-carat gold plate over the incisal section, leaving the ends of the plate extending out sufficiently beyond the edge of the porcelain to retain it in position in the investment. The metal used in backing a front should be annealed during the process, and the portion which comes in contact with the porce- lain closely adapted by pressure and burnishing. Close contact affords better support to the porcelain and greater continuity of structure to the crown. When plate is used for the backing a die may be used, to assist in adapting it closely to the porcelain. An 8 92 CROWN-, BRIDGE-, AND PORCELAIN-WORK. intaglio die sufficient for the purpose can be quickly formed by pressing the back of the front against the surface of a piece of im- pression-compound, Dental Lac, or sealing-wax, chilling the mate- rial, and removing the front. The plate can be swaged against the surface of the porcelain in this die. Another method is to place the porcelain tooth with the backing on it in position wrapped in tissue paper in a swager. The pressure should be gradually increased from light to heavier blows from the hammer on the plunger. In backing porcelain fronts the metal used should be neatly trimmed to the sides. It must not be bent over the edges closely, especially at less than a right angle, as expansion and con- traction of both porcelain and solder are very liable to cause fractures. Preparation for Investment — The porcelain front when backed is adjusted on the cap. Should the metal backing the base of the front interfere with its proper adjustment on the cap, as is liable to occur at the cervico-labial section, it should be thinned with a small corundum cone, or entirely removed at the obstruct- ing point, and that portion of the porcelain allowed to rest directly on the cap. The front is first attached to the cap with only a small quantity of adhesive wax, until its alignment is quite accurately determined, when hard wax is added to more securely retain it. The whole is then chilled in cold water and a final adjustment made to positively assure its correctness. Before investing, addi- tional wax is added to the metallic parts of the crown sufficient to impart to them the desired form when soldered and also to allow additionally a slight excess for finishing. A little wax is generally placed on the sides of the collar at the cervical section of the porce- lain front, especially where any portion of it projects over the line of the collar, for the purpose of providing space in the investment for the solder to flow and contour the part. When the porcelain projects beyond the edge of the collar at Fig. 156. the cervico-labial section, as frequently occurs in cases of cuspids, a space is left, such as is shown at A, Fig. 156. This space should be evenly filled with gold solder when the front is being attached to the cap. To accomplish it the platinum foil applied to the base of the porcelain should be extended over the whole sur- face and slightly beyond the edge of the porcelain at GOLD COLLAR CROWXti ^YITH POIICELAIX FROXTS. 93 Fig. 157. the cervico-labial section. The open space is filled and shaped evenly with wax a little flush at the edge of the collar. To assist in drawing the solder to the part, a narrow strip of Xo. 30 rolled gold foil may be neatly adapted over the surface of the wax. Should the foil extend slightly beyond the edge of the wax and rest on the surface of the porcelain, it will not cause fracture if closely adapted to the surface. In such cases the flowing of solder to the part is further facilitated by forming an aperture either on the bottom or on each side of the investment, which will expose it and if necessary permit solder to be applied directly. This can be most easily done by attaching a small cone of wax, as indicated by the dotted lines in Fig. 157, before in- vestment, thus forming a channel, the orifice of which can afterward be shaped or enlarged. Investment. — Calcined marble- dust and plaster is the generally preferred material for investment. It is used in the proportions of two part- of marble-dust to one of plaster. Potassium sulfate may be added to the water to hasten the setting, in the proportion of one small teaspoonful to a pint of water. The crown is first wet by dipping in water and then a little of the investment material is placed in the inside of the cap. Another portion is next placed on a piece of paper in the form of a small mound, and the crown is gently pressed into it until all the parts are covered except the wax on the palatal side of the backing. When the in- vestment has set, it is trimmed and reduced in size as much as it properly can be and the investment material removed, so that the metallic parts of the crown are slightly ex- posed at the side, as shown in Figs. 157 and 158. The wax is removed by pouring boiling water on the in- vestment. Instruments should not be used to remove wax, as they are liable to disturb delicately adjusted parts. Borax ground fine, mixed with water, or liquid flux, is applied with a brush to the metallic parts and in the seams before heating. When Parr's fluxed wax is used for the benefit of the flux it contains, the wax Fig. 158. 94 CROWN-, BRIDGE-, AND PORCELAIN-WORK. is allowed to burn out as the investment is heated. The objection to burning wax out is that the resulting debris is liable to pit the solder slightly. • Soldering and Finishing — The investment should be first dried and heated to a dull red over a Bunsen flame (see Part V, Chapter IV) and then removed to a soldering-block. Gold solder, cut into small pieces, in quantity only sufficient to fill interstices and unite front to cap, is placed in and over the aperture between the front and cap. The solder should have been previously im- mersed in borax finely ground in water and then dried; or, after it is placed in position, it should have a small quantity of calcined borax or Parr's flux sprinkled over it. By heating the investment uniformly, especially underneath, and in the direction A, Figs. 157 and 158, with the large flame of a gas blowpipe, the solder is melted and gradually flowed downward and between the front and cap and in the interstices between the pieces of metal forming the backing. More solder is added by degrees and fused in this manner until the spaces between the porcelain and cap and at the sides are filled in and continuity of structure assured. After letting the body of the investment cool slightly, so as not to draw bach the solder that has been already fused in the deep portion of the investment, additional solder is placed on the backing and cap, and with a small-pointed flame flowed over these parts. Only sufficient gold should be applied to properly contour the parts. When soldered the investment should be allowed to cool slowly, the crown re- moved and boiled in acid to thoroughly remove the borax, and then trimmed and polished. In finishing, the motion of the wheels in trimming and polishing should be so directed that the edge of the metal adjusted to the porcelain is brought against the surface. Fig. 159 represents the completed Fig. 159. crown. A more expeditious method of constructing this style of crown, which is practiced to some extent, is to unite the post and porcelain front to the cap in one soldering, as f ollows : After having fitted the post to the root-canal and cap, lay the post aside. The porcelain front is- next ground and adapted to the cap, properly backed with metal, attached in position on the cap with wax cement, adjusted in the mouth, and removed. The pin is next warmed and placed in position by GOLD COLLAR CR0WX8 WITH PORCELAIN FRONTS. 95 passing the end through the hole at the inside of the cap into the wax attaching the porcelain front. The whole is next adjusted in the month to get the exact line of the pin, carefully removed, in- vested, and soldered. Bicuspids and Molars. — Bicuspids crowned by this method will have greater strength if a portion of the palatal section of the natural crown is preserved (Fig. 27), because of the support it affords to the collar which will cover it. The end of the root is capped after the manner of the typical central already described, one or two pins being used in the canals as required. Where only one pin is used, it is best inserted in the palatal canal. A porcelain cuspid tooth, or a bicuspid front, is then ground, backed, and adjusted on the cap to represent the labial aspect, and secured with wax. It is carefully adjusted in the mouth, and the occluding edge of the porcelain is ground to clear the antagonizing teeth (A, Fig. 160). With a die of Fig. 1G0. Fig. 161. Fig. 162. Fig. ]f>4. Fig. 165. suitable size representing the occluding surface of a bicuspid, as illustrated in Fig. 161, a piece of pure gold plate (about jNTo. 30 gage) is swaged (Fig. 162) and the cusps filled in with 18-carat solder or gold plate. 1 The cap is then trimmed (Fig. 163), ground, and fitted to the occluding edge of the porcelain front (Fig. 164) in proper position as regards occlusion, and the wax attaching it is shaped to the contour of the crown (A). A piece of very thin gold plate or of "No. 60 foil (B) is then adjusted on each approximal side of the crown, which is invested (Fig. 165). The long ends of the side-pieces of gold plate are designed to retain 1 A hard-flowing solder is best for use in filling cusps to protect porcelain fronts to crown- or bridge-work. It is made of two parts 18-carat gold plate and one part 18-carat solder. The plate and solder should be melted together and rolled out quite thin and kept ready for use (Part V. Chapter I). 96 CROWN-, BRIDGE-, AND PORCELAIN-WORK. them in position, as the investing material may be removed from the portion inclosing the sides of the crown (A). Mica — isinglass — may also be used as suitable for this purpose instead of gold. In the process of soldering, the solder is placed in the aperture at B, and the flame of the blowpipe being directed on the exposed sides of the gold at A, the solder is flowed into every part, form- ing perfect continuity of structure of the metallic portion of the crown. If this aperture at A is left open without the gold or mica, and the solder is first flowed in the interstices as described in soldering an incisor crown, the remaining solder necessary to con- tour the part can be added, if the pointed flame is used and not applied to the other portions of the crown and investment. In finishing, the surplus gold is trimmed to the contour of a bicuspid tooth. Fig. 166 represents the finished crown. In difficult cases and occlusions the work is simplified by first soldering the porcelain front to the cap. The crown is then ad- justed in the mouth and the porcelain ground to properly clear the occluding teeth and allow space for the gold cap. The gold cap is next adjusted in position, the parts shaped with wax inserted, and the soldering completed. To form the occluding and palatal section of the crown in exact accordance with the occluding teeth, where the occlusion is abnormal, the parts are to be first neatly modeled in hard wax and a die cast of the occluding surface. From this a cap can be stamped that may be easily fitted to prop- erly occlude. The method described produces a perfect and artistically formed crown, but simpler and quicker methods are practiced. One of these is to build up the palatal cusp with several pieces of gold plate, which have been previously melted into the form of small balls and flattened out on an anvil. These, laid in position and united with solder, are shaped in finishing to represent the palatal cusp (Fig. 167). The porcelain front should be backed so that the solder can be flowed over its occluding edge. Another method is to extend the palatal part of the collar down, as shown in Fig. 168, and then fill in the space with solder. In finishing, the gold is trimmed to the form of the crown. As much as possible of the natural crown should be left at the palatal side of the collar, the exposed edge of which may be slit and brought in against the side and soldered to give contour. With this form of collar one pin, in the palatal root-canal, is sufficient. GOLD COLLAR CR01YXS WITH PORCELAIN FRONTS. 97 It should be allowed to extend out of the cap enough to just touch the lower teeth when they are occluded. The exposed end of the pin will be an exact guide as to the amount of solder re- quired to form the grinding-surface. In this and in the method Fig. 1G6. Fig. 1G7. Fig. 168. Fig. 169. Fig. 170. W v , R previously described, the porcelain front may be soldered and the palatal cusp formed in the one investment. A faulty method of forming bicuspid crowns, especially in a close occlusion, and one to avoid, is the shap- ing of the palatal side, as shown at W, in Fig. 170. The occluding surface should be shaped so that the cusp of the occluding tooth shall be interlocked in occlusion, as illustrated at E, Fig. 170, instead of glanc- ing off. In the latter event, the root is liable in time to be forced outward and loosened. For a description of the Hollingsworth method of attaching a Fig. 171. Fig. 172. Fig. 173. porcelain facing to a gold cap the reader is referred to Part III, Chapter XIV. The method of construction of molar crowns with porcelain fronts is similar to that for bicuspids (Fig. 169). 98 CROWN-, BRIDGE-, AXD PORCELAIN-WORK. Saddle=back Tooth. — The saddle-back tooth is a porcelain tooth in which the base curves in an unbroken line from the buccal surface at the neck to the heel at the palatal side, without any shoulder, the pins being inserted as shown in Fig. 171. The base of the porcelain tooth selected should be at least as large as the surface of the cap (Fig. 172). When the tooth is ground and fitted, it is backed flush to the edge of the base with pure gold No. 34 gage, or platinized gold (pure gold alloyed with 2 to 3 per cent, of platinum), still thinner, waxed in position on the cap (Figs. 172 and 173), and invested so that the seam of wax shall be fully exposed. In soldering, the flame must be directed under the investment, to draw the solder into the seam. Dr. Stovvell's Method of Applying a Countersunk Tooth or a Logan Crown — A countersunk tooth or a porcelain crown can be soldered on the cap, according to Dr. S. S. Stowell's method, as follows :* ''The tooth used may be a Logan crown or an ordi- Fig. 174. Fig. 175. Fig. 176. Fig. 177. Fig. 178. nary countersunk tooth, but in most cases the Logan crown, hav- ing a strong pin, is preferable. The pin is first cut off, then the tooth is ground to fit on the cap, the porcelain and the stump of the pin being reduced alike evenly and smoothly; after which the stump of the pin is ground with a small wheel below the surface of the porcelain (Fig. 174). The tooth is then invested (Fig. 175) and pure gold fused on to the platinum pin, and while in a fluid state it is 'spatted' down flat with a wax spatula (Fig. 176). The gold is then filed or ground down even with the porcelain, and at the palatal border the tooth is ground to bevel back 'until the gold is reached (Fig. 177). The tooth is then secured in place on the cap with wax cement (Fig. 178), the case invested, and heated until the wax has melted and burned out. A small clipping of thin platinum plate is crowded into the opening (Fig. 179) caused by the grinding of the bevel on the crown. The 1 Dental Cosmos, vol. xxix, page 641. GOLD COLLAR CROWNS WITH PORCELAIN FRONTS. 99 clipping of platinum serves as a lead for the solder, which fol- lows it down into the countersunk cap, around the ends of the dowels, and finally attaches itself to the pure gold already at- tached to the stump of the platinum pin. Fig. 180 represents the completed crown. A sectional view of a like crown (Fig. 181) also shows the organization in detail. A porcelain crown can be used to represent any of the teeth in the same manner. (See Figs. 182 and 183.)" Fig. 179. Fig. ISO. ^j '-,- Fig. 181. Fig. 182. Fig. 183. For the construction of crowns of the last two styles described, considerable space between the surface of the end of the root and the occluding teeth is required, as a shallow intervening body of porcelain, unprotected by metal, is liable to fracture. Crowning in Cases of Abrasion. — In a case of extensive abra- sion of the incisal edges of the anterior teeth, with Pjc lg4 pulp living though considerably calcified in the coro- nal section, crown-work to restore the length and form of the teeth is best performed by removing a portion of the labial aspect of the natural crown and then forming the artificial crown similar to a gold collar crown with a porcelain front without the pin. Fig. 184 gives an outline of the construction of such a crown. If a case should suggest the necessity of a pin, a short one can be inserted between the line of the pulp-chamber and the palatal wall. In case the tooth is pulpless, the canal can be opened up and the post extended into the root of the tooth. The incisal edge of the porcelain should be well protected by the use of clasp gold and solder instead of the ordinary gold plate. When an incisal surface of considerable thickness is suggested, it is best built to the desired depth after the first protecting piece has been soldered, by applying successive layers of plate rolled 100 CROWN-, BRIDGE-, AND PORCELAIN-WORK. thin, of the size of the incisal edge, each being perforated with two or three holes with punch forceps, so that the solder shall more easily flow between and unite them. (See article on "Gold Tips," Chapter XV.) Gold Crowns with Porcelain Fronts for Teeth with Living Pulps. In the anterior teeth, in case of atrophy or erosion, or where decay has destroyed the approximal sides of a tooth in such a manner that crowning is considered the most desirable opera- tion to perform, the pulp is frequently found unexposed and in a normal condition. The importance of its preservation in such a case is unquestionable. The crowning of such cases with gold jacket-crowns, carrying a porcelain front attached with solder, is generally a questionable procedure. The room required for the gold and the small space left for the porcelain, together with the difficulty of securely attaching the latter, render such a construction rarely practicable. Jacket-crowns for such cases are now best made of platinum and porcelain, to which the reader is referred (Part IV, Chapter VI). The construction of gold crowns with porcelain inlays for bicus- pids is also described in the same chapter, and in the account of the Hollingsworth System (Part III, Chapter XIV). CHAPTER VII. All-Gold Collar Crowns for Bicuspids and Molars Constructed in Sections. methods op knuckling the collar and giving contour— forming the occluding surface, methods nos. 1, 2, 3, 4, 5, 6, and 7— all-gold-crowns for incisors and cuspids — cases of abra- SION. The root and crown having been properly prepared, the collar is formed and adjusted as described at page 75, and the edge toward the antagonizing teeth trimmed, to fully clear them in occlusion. The collar is then slightly expanded toward the occlud- ing surface for better contour. Fig. 185 A. Fig. 185 B. Fig. 186. Methods of Knuckling the Collar and Giving Contour. If the collar is long enough, a contour, approximately that of a natural tooth, can be imparted to the side with the aid of suitable pliers, such as are illustrated in Fig. 125, one beak of which is 101 102 CROWN-, BRIDGE-, AXD PORCELAIN-WORK. rounded at the point and shorter than the other. The Johnson and Reynolds forms, Figs. 185 A and 185 B, are also useful for shaping the plate and removing inequalities caused by the use of the first form. Contour may also be given by a mandrel die, or mold (Fig. 186). A close knuckling can be insured by press- ing the collar against the approximal tooth in the manner shown in Fig. 187. Methods of Forming the Occluding Surface or Cap to the Collar. Method No. 1. — The collar, having been fitted (Fig. 188 A represents a typical case), is removed, filled with plaster, and ad- justed in position. The antagonizing teeth, having been covered with a piece of tin foil, are then occluded until the plaster sets. (See Fig. 188 B.) The collar is then removed. The surface of the plaster inside the collar will give the impression of the natural root or crown, Fig. 187. Fig. 188 A. Fig. 188 B. and the outside that of the antagonizing teeth. The latter fur- nishes an outline to form the grinding-surface of the crown. The plaster at the occluding section is then trimmed and shaped to represent the cusps and fissures of the natural tooth, enough of the surface being removed to allow for the thickness of the plate that forms the cap. In shaping, the typical forms of grinding- surfaces, illustrated in Fig. 199, can be used as a guide. A small tube of copper, a trifle larger in circumference than the crown under construction, is filled with Melotte's "Moldine," and the surface rubbed with soapstone. An impression of the lower portion of the form of the crown A to the line B, Fig. 189, is then made in the moldine, and a strip of paper wound around the tube, extending about an inch above the edge. Fusible alloy is then melted and poured into the mold, thus forming a die. An indentation is made with a punch in a block of lead, into which the die, when cold, is hammered slightly beyond the impression Fig. 189. Fig. 190. A ALL-GOLD COLLAR CROWXS COXSTRUCTED IX SECT10XS. 1Q3 of the edge of the collar. By this method a die and a counter- die (Fig- 190) can, with practice, be completed in five minutes. With this die the cap is then struck up on the lead from a flat piece of plate and fitted to the collar. 1 A little of the surface of the plaster in the collar may have to be removed from under the cap, if, on trial in the mouth, the model or the cap is found a little flush. The crown, with the plaster still inside the collar, is fixed in a soldering-clamp of one of the forms shown in Figs. 191, 192, 193, and 19 6, which holds the parts together and permits the flame to reach all points. One of the points of the forms illustrated in Fig. 193 may be shaped to that shown in Fig. 196 to hold the cap in position on the collar, while the other point is used to support the collar. With the clamp (Fig. 191), the blow- pipe flame is the best. The other forms suggest the Bunsen flame. The parts of the crown can also be held together for soldering with iron wire in the form of a loop passed over the grinding- A. Fusible-metal .lie. 13, Counter-ilie. C, Plate to form the cap. Fig. 191. Fig. 192. surface, against the sides of the collar, with the ends twisted to- gether over the aperture of the neck of the crown. Xo more solder should be used than is necessary to unite the parts or give any required contour, as an excess necessitates additional labor in finishing:. 1 For a description of the use of Dental Lac to form molds for the purpose of swaging caps, etc., see Part V, Chapter III. 104: CROWN-, BRIDGE-, AND PORCELAIN-WORK. Fig. 193. Method No. 2. — If the crown is not to be contoured with the aid of the solder, when the cap is struck up, melt solder into the cusps, and then adjust the cap in position on the collar, for which purpose some of the plaster underneath the cap must be removed. A jet of flame from the blow- pipe is then thrown upon it in such a maiiner as will cause the solder to flow down on the edge of the collar and fill the seam from the inside. The objection to this method is that, when a large por- tion of the natural crown is inclosed by the gold, the solder will occasionally alter the inside form of the fitted cap, thereby interfering with its adjustment, which is a defect troublesome to correct. Method No. 3. — This method is spe- cially suitable in cases where all or nearly all of the grinding-surf ace of the natural crown is present or where the bite is close. Adjust the collar in the mouth, and, with a small piece of wax or im- pression-compound pressed upon it, take an impression and "bite," in which the collar shall be imbedded and re- moved. Witlf this a model and articu- lation are made and the form of the cap shaped in wax. An impression of the cap is then made, either in moldine in a soft state in a tube, or in plaster, and a die cast. The cap is stamped on this die, then adapted to the collar by the model, and the crown finished. This method 1 can be adopted when it is pre- ferable to construct the crown between the visits of the patient, after having first made and fitted the collar. Method No. Jf. — In utilizing a tooth as an abutment in bridge- 1 Dr. N. W. Kingsley's method. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. 105 work when all or nearly all of the occluding surface of the natural crown is present and for any reason very little of it can be re- moved, a practical method of construction is to mark the out- line of the occluding surface on the inner surface of the collar; then remove the collar and trim so as to leave a border of about one-sixteenth of an inch outside the mark. This border is then thinned with a corundum-wheel, and slit as seen in Fig. 194. The collar is next adjusted on the natural crown, and the slit bor- der bent over to the form of the occluding surface, to which it is burnished. A piece of pure gold plate, about iSTo. 30 gage, is then placed on the occluding surface of the tooth and adapted to it and to the collar. The gold may be first struck in the form Fig. 195. Fig. 196. of a cap on a block of lead, hammering into it a die of the surface of the tooth to be crowned (Fig. 195), or one corresponding closely, made with a cusp button as described in the Hollingsworth System, Part III, Chapter XIV. The antagonizing teeth are then occluded on the gold, which is thereby pressed to form to articulate with the occluding surfaces. Enough of the occluding surface of the tooth crowned or of the cusps of the occluding tooth ought to be removed to allow for the thickness of the gold covering its surface. The collar and cap are next removed and soldered. This is done by resting the collar on the cap, which is held by a pair of tweezers, or by clamping the cap and collar together and placing the solder in small pieces around the collar outside the cap, at A, Fig. 196, and soldering by holding in a blue gas flame. Only 106 CROWN-, BRIDGE-, AND PORCELAIN-WORK. sufficient solder should be used to join and fill the seams, so that it will not interfere with adjustment on the natural crown. A closer and neater joint will be obtained by at first attaching only one corner of the cap to the collar, with the smallest possible quantity of solder, then readjusting collar and cap on the tooth, adapting their edges together with a foot-shaped foil condenser, and then completing the soldering. Method No. 5. — When intervening space will permit the forma- tion of a solid gold occluding surface to a collar crown, the follow- ing is a very practical method : Fit the collar and trim the edge toward the occluding surface so as to leave between it and the cusps of the occluding teeth a space of at least one-sixteenth of an inch. Remove the collar, and solder over the occluding surface a flat piece of gold plate about No. 30 gage for bicuspids, or platinum about ~No. 34 for molars, preferably using a small quantity of hard- flowing solder. Trim off the surplus plate flush with the collar. To form the cusps: Melt scraps of gold plate on the surface of a soldering-block in small globules, one for each cusp, and slightly flatten each globule on an anvil with a hammer. Place the globules on the surface of the cap in proper position to form the cusps and attach each with a small piece of hard-flowing solder (Fig. 197). When all the cusps are attached, then melt on sufficient ordinary solder to properly fill in and give form to the surface of the cap. Adjust the cap in the mouth and trim the gold of the occluding surface to a form which will permit the occlusion of the other teeth, then polish the crown. This is a very practical and quick method of forming a gold crown. Method No. 6. — The methods described insure a perfect occlu- sion of the crown with the antagonizing teeth. In the absence of antagonizing teeth, or when the general form of the grinding-sur- face permits it, the cap can be struck up With a die similar to the one shown in Fig. 195 that approximates in size and form what is required. The cusps are then filled in with 18-carat gold plate, hard-flowing solder, or ordinary solder, and the edges of the inner surface of the cap ground level on the side of a corundum-wheel. The entire circumference of the edge of the collar is also leveled, and the cap adjusted, clamped, and united. If the cusps of the cap are filled in with solder, it will flow down and join the collar on the inside; if with gold plate or hard-flowing solder, the cap and collar must be joined with solder either on the inside or outside. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. ^QT Method No. 7. — When the mere form of the grinding-surface for the crown is all that is required, an impromptu one may be made by indenting a piece of pure or soft gold plate with the round end of an instrument-handle on a piece of lead to form the cusps, Fig. 198. then reversing the cap, resting it on a flat surface, and creasing be- tween the cusps with a burnisher. One large indentation, such as is shown in Fig. 198, A, when indented and creased across the Fig. 199. UPPER LOWER center with the edge of a flat, thin burnisher, will represent a bicus- pid. Four indentations closely made, as shown in Fig. 198, B, when creased between, can be used to represent an upper or lower 9 108 CROWN-, BRIDGE-. AXD PORCELA.IX-WORK. molar, and three similar indentations, properly creased, a second or third upper molar, as seen in Fig. 198, C. Method No. 8. — Metallic caps, or forms of the occluding sur- faces of teeth for use in constructing crowns, are quickly made with a die-plate, such as is shown in Fig. 199, * v 'in which are four groups of intaglio dies representing the peculiar cusps of the bicuspids and molars. The hubs A, B (Fig. 200) are of the sizes shown, and are made of an alloy composed of tin one part, lead Fig. 200. four parts, melted together. The mold C should be warmed, the metal alloy poured in every hole, and the overflow wiped off ■just before the metal stiffens; Fig 201 . . this will make the butts of the hubs smooth and flat. After a minute or two the mold may be reversed, the hubs shaken out, and the casting process con- tinued until a considerable num- ber of hubs shall have been made. In Fig. 201 a molar hub is shown in place on a piece of .No. 32 gold plate, which lies over the upper right first molar die. A succession of blows on the hub with a four-pound smooth-faced hammer will drive the Dental Cosmos, vol. xxix, page 482. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. ^Q9 plate into the die, and at the same time spread the hub metal from the die center to its circumference, in such a manner that the plate will be perfectly struck up with the least possible risk of being cracked. The flattened hub is seen in Fig. 202, which also shows at D the obverse of the struck-up hub, and at E the cameo of the struck-up plate, having every cusp and depression sharply defined. The counter-die plate (Fig. 199) is made of a very hard cast metal, which will admit of the striking-up of many crown plates by the means described, if the crown plates be not too thick and stiff. Of course, they should be annealed be- fore they are placed over the die. If a cusp or fissure should Fig. 202. Fig. 203. A chance to crack in hubbing, a small piece of plate may be struck up over the fissure, and then soldered to the original cap." The methods which have been described for the construction of all-gold bicuspid and molar crowns are those generally adopted in practice. Of others, Dr. J. J. E. Patrick's method 1 consists of first forming a very narrow collar and telescoping it with a seamless cap of the form of the crown, and sol- dering along the line of the cap to the collar. When the upper edge of the collar is lapped over on the grinding-surface, as shown in Fig. 203, the soldering can be done through the aperture A. 2 AIl=Gold Crowns for the Incisors and Cuspids — AVhen the teeth are abraded and short, with flat incisal edges (Fig. 204), and the all-gold crown required is to correspond in form or be only a little longer, the gold collar, after being fitted to the tooth, is slit 1 Dr. Patrick, the Dental Cosmos for October, 1888, page 706. - Dr. R. H. Adair's method. 110 CROWN-, BRIDGE-, AND PORCELAIN WORK. on the palatal or lingual side, and bent and burnished to it. The collar is then removed and the seams soldered together. This is best done by holding the collar in a Bunsen gas flame, with the solder placed in position in very small pieces, and only sufficient in quantity to join the seams. The collar is next adjusted to the tooth, and the gold at the incisal edge trimmed even. A flat, Fig. 204. Fig. 205. thick piece of gold plate or clasp-material is soldered across the incisal edge to form and inclose that portion of the crown. Fig. 204 represents a case of abrasion of the lower teeth, to which all-gold crowns have been applied to open the bite, as shown in Fig. 205. In such cases, owing to the attrition of the occluding teeth, the cap forming the occluding surface should be constructed of heavy gold clasp-plate and solder. An artificial plate replaces the upper teeth. ALL-GOLD COLLAR CROWNS CONSTRUCTED IN SECTIONS. m AY hen the gold crown required is of the normal form, the collar when properly fitted should be cut away at the palatal section, as shown in Fig. 206. The edge of the gold is then chamfered, and bent and burnished over the incisal edge and sides, close to the natural tooth. To this open section is next adapted a flat piece of gold plate, the collar is removed, and the parts are soldered together, using very little solder. Small pieces of solder or solder filings can be melted in the interior of the incisal edge to increase its thickness, if necessary. Another method is to select a porcelain tooth of the desired form and of the size of the gold crown, and use it as a model to cast an intaglio die. The die is made by placing moldine in a pill box, smoothing off the surface, and imbedding half of the porce- lain tooth with the palatal or pin side down. Xext wind paper around the box, slightly warm the porcelain tooth, and pour in fusible metal. On separating and removing the porcelain tooth from the fusible metal, you have an intaglio die of the face of it. The use of Dental Lac for this purpose is described in Part V. On this intaglio die shape a piece of soft gold plate, Xo. p ., - 30 to 32 gage, to the form of the labial surface of the crown. Remove, bend, and burnish the metal round to the form of the sides and palatal section of the tooth. trim the meeting edges, and solder (Fig. 207). 1 A fusible-metal die of the prepared form of the natural tooth is a material aid in the construction of any of these styles of crown. In pulpless teeth with only a little or none of the natural crown remaining, the root can be shaped and capped as for a collar crown with a porcelain front (see page 83) with a post in the root- canal, and a gold front applied instead of one of porcelain. This is done by shaping or stamping the form of the labial face of the tooth required in gold plate, mounting it in position on the cap as in the case of a porcelain front, and attaching with solder. The concave portion at the palatal side of the gold front is filled in and shaped with solder at the same time. 2 The construction of an all-gold crown for an incisor or cuspid is most easily accomplished by the seam^ss method described in Chapter VEX 1 Dr. J. T. Usher. Dental Cosmos, vol. xl. 2 Dies and molds to shape plate for these purposes can now be found in the Hollingsworth and other crown outfits. CHAP TEE VIII. The Gold Seamless Cap-Croavn System. seamless root-caps for crowns with porcelain fronts— in- cisors, cuspids, and bicuspids — impressions and dies — method op stamping seamless metal caps— all-gold seam- less bicuspids and molars— models, dies, and method of swaging — all-gold seamless incisors and cuspids. This method consists in the use of a gold seamless cap for the construction of the required root-cap or crown. Seamless Root=Caps for Incisor, Cuspid, and Bicuspid Crowns with Porcelain Fronts. — Incisor, cuspid, and bicuspid crowns with porcelain fronts are constructed by this method as follows: The natural crown is ground down to within about one-eighth of an inch of the gum at the palatal wall, or enough to clear the antagonizing teeth when occluded, and slanting from the posterior edge of the pulp-chamber to the cervico-labial edge of the gum and slightly under its margin if it is desirable to conceal the joining of the crown with the root. The sides are shaped the same as for a collar crown (Fig. 208). Impressions and Dies. — A die of the end of the root is next made. For this purpose an impression of the part is taken with gutta-percha on the end of a piece of wood trimmed to the proper size, or, better still, by placing a thin mixture of plaster of Paris to which a little potassium sulfate has been added, or some moldine, in a tube formed of a strip of copper about one and one-half inches in length and three-eighths of an inch in diameter, cut out on the sides to the depth of half an inch, with the flange for the palatal side shortened 1 (Fig. 209). The impression thus taken will be confined almost entirely to the end of the root to be capped. When gutta-percha is used, it is cooled and dried perfectly. A strip of paper is Fig. 208. Fig. 209. 1 See Part V, Chapter III, which describes how to make soldering. 112 tube without THE GOLD SEAMLESS CAP-CROWN SYSTEM. 113 tied around the wood or tube, and a die cast with the fusible metal. The cooling is hastened by immersion in a glass of water. When cool, the die is removed from the mold, and the metal is trimmed, with file and chisel, a little deeper than the gum has permitted the impression of the root to be taken, and without altering the form of the end of the root (Fig. 210). A counter-die is then made by driving a punch of suitable size into the surface of a block of pure lead, into which with a few blows of a hammer the die is forced. Methods of Stamping Seamless Crowns. — A cap of pure gold, or preferably of platinum, with which to cover the root is first Fig. 210. Fig. 211. Fig. 213. Fig. 212. made. This can be formed by placing a piece of the plate, ~No. 30 gage, of suitable size upon a block of lead, and with an oval-shaped punch one-fourth of an inch in diameter gradually driving it into the lead until the gold has assumed the shape of a cap about an eighth of an inch in depth (A, Fig. 210). The gold should be protected from the lead by the intervention of a piece of thin kid and should be withdrawn from under the punch and annealed from time to time during the process, otherwise, as in all such operations, it is liable to be cracked. Caps of metal can be made in different sizes and kept on hand for use in this and other styles of crown-work by means of a stamping machine, which in principle is such as is used by jewelers for forming cap-shaped pieces of gold, and in factories 114 GROWN-, BRIDGE-, AXD PORCELAIN-WORK. for making copper cartridges. The gold plate, cut into circular pieces, is pressed through a steel die-plate, with punches gaged to the holes; at each punch a small portion of the gold is turned over, thus preventing its lapping or creasing. Repeated annealing of the metal is very necessary in this process. A properly con- structed press should be used for the purpose, such as is illustrated in Fig. 214, instead of hammering the punches through the plates, because when treated in that manner the metal is liable to be torn or creased. The cap is then annealed and swaged on the die to the form Fig. 214 The form of stamping machine introduced by the late Dr. J. J. K. Patrick. of the end of the root (B, Fig. 210). The palatal portion of the cap should be allowed to go well up under the free edge of the gum, and at the cervico-labial edge it can be, if preferred, cut out to the edge of the root. In the process of adjustment, the edges which fit under the gum should be marked and trimmed as directed in describing the construction of a collar crown, and then burnished close to the sides of the root and into the orifice of the root-canal, forming a perfect-fitting seamless cap (Fig. 211). A platinum pin is then fitted in the root-canal and soldered THE GOLD SEAMLESS CAP-CROWX SYSTEM. 115 to the cap (Fig. 212), as in the construction of the gold collar crown with porcelain front (page 86), with which operation the re- mainder of the process of construction is identical. Fig. 213 repre- sents the completed crown. The advantages of this style of crown are, simplicity, as the formation of a collar is avoided, and strength, as a large portion of the natural crown can be left at the palatal side. This affords a stronger and more reliable foundation than can be obtained at any other point, as the direction of the force in mastication is forward at an angle with the line of the root, and although the metal of the cap, where it encircles the root at the cervico-labial edge, is entirely removed, the crown is still held securely. AlUGoId Seamless Bicuspids and Molars. — All-gold seamless crowns for bicuspids and molars that will accurately fit the natura ( crown and root, and occlude properly with the antagonizing teeth, are easily and quickly formed, if sufficient of the natural crown remains to admit of temporary restoration of its contour with gutta-percha or any other suitable plastic material. The sides of the natural tooth and the occluding surface should be removed at least the thickness of the plate to be used. Models, Dies, and Method of Swaging. — An impression of the restored tooth is next taken in plaster or moldine in a thin copper tube which will fit under the free margin of the gum and closely encircle the tooth, as explained on page 112, and in Part V, Chap- ter III, which also explains the construction of the copper tube. A die is then formed of fusible alloy; or a plaster model can be made from an impression of the tooth taken in wax, and a mold obtained from the model with moldine. Additional preparation and shaping of the natural crown to receive the artificial crown can then be proceeded with. Where the natural crown is very badly decayed or broken down and the method just described is not practicable, the por- tion of the natural crown or root remaining should be shaped and prepared to receive an artificial crown. Then the form of the cervix is ascertained with a wire, as described on page 78, an impression of the parts taken in wax or impression-compound, and the wire form, the twisted ends having been shortened, is carefully adjusted on the wax at the cervical line. The plaster model, when made, will show the wire slightly imbedded in the plaster. The plaster should be trimmed to the inner edge of the 116 CROWN-, BRIDGE-, AND PORCELAIN AYORK. wire, as that represents the exact form of the root (Fig. 215), and the wire cut and removed. Another method is to fit a copper collar accurately to the root with projecting points on the sides of the collar, which will remove in the impression. In such a case plaster must be used for the impression. When the model is made the collar, on being cut and removed, will represent the exact form of the neck. From a "bite" taken in wax and fitted on the model a plaster articulation is then made. A hole is drilled in the center of the form of the root on the model to be crowned. In this hole, and over the end of the root, a ball of soft plaster, slightly colored with carmine, is placed, and the teeth of the articulation, covered with tin foil, closed on it. This, on separation, gives the outline of the form of the grinding-surface for the crown. The sides of the Fig. 215. Fig. 216. plaster are then trimmed to the form of the crown, and the whole carved in detail (Fig. 216). As the crown will always stamp larger in circumference than the die, in proportion to the thick- ness of the gold used, it should be remembered allowance must be made by trimming off a proportionate amount of the grinding- surface, either before the impression of the natural tooth is taken, or, from the plaster model of the tooth when it is shaped. The former is the preferable method to practice, as the latter will after- ward require the removal of at least the same proportionate amount from the natural tooth when the crown is fitted, which is not always easily done. When the plaster model for the crown is made, it is separated from the rest of the model at the dotted line seen in Fig. 216, and trimmed in the form shown by the cast A, Fig. 217. From this model the die is made in a tube with moldine and fusible metal, as TEE GOLD SEAMLESS CAP-CROW^ SYSTEM. 117 already described, and in Part V, Chapter III. The cast should always be lengthened at the neck, so that the crown when con- structed shall have a surplus in depth of gold to allow for any trimming or shaping of the collar that may be required. The counter-die (B, Fig. 217) is made by punching a hole in a block of lead and hammering the die into it. The crown, which is usu- ally formed of gold only slightly alloyed, or gold lined with very thin platinum from Xo. 29 to No. 32 gage, is then made by first stamping a piece of plate (see page 114) in the form of a cap of Fig. 217. Fig. 218. Fig. 219. gold (A, Fig. 218), which is then placed on the cast, tapped with a horn hammer to the general shape, and with the aid of the counter-die (B, Fig. 217) swaged to the form of the crown B, Fig. 218. A piece of kid-leather or rubber-dam should be used to cover and protect the gold from the lead, and to facilitate its removal from the counter-die. An allow- ance for the thickness of the gold must be first made, by driving the die with two thicknesses of kid, without the gold on the cast, into the counter-die to enlarge it. If this is not done, the gold is liable to be torn in the swaging. AU=GoId Incisors and Cuspids. — Incisor and cuspid crowns from which a portion of the gold on the labial aspect is to be re- moved (see article on "Shell Anchorage," page 210), or which are to be used entire as supports for bridge-work, can usually be ad- vantageously formed with seamless caps (Fig. 219). The necks of these crowns will usually have to be contracted in fitting in a contracting plate, or slit, lapped, and soldered. CHAPTER IX. Imparting Contour to Seamless Gold Crowns. crowns swaged on dies— method of slitting and contracting the neck — use of contouring pliers— external application of metal— to contour on the die with a swager — sectional mold method— formation— molds— shaping the cap— ready- made gold crowns. Crowns Swaged on Dies. Method of Slitting and Contracting the Neck. — Crowns for cases in which decay has extensively involved the approximal sides, owing to encroachment of the adjoining teeth, generally require very little if any contour. Some form can be imparted to a straight- sided seamless crown by slitting the collar directly in the center of the palatal side, contracting the neck, tapering the nnderlapping portion, adjusting on the tooth, burnishing the gold, removing, and soldering. This contraction also imparts a very close fit to the collar. When considerable contour is required, the crown should lie formed with the desired size and shape of grinding-surface. The collar is then to be slit and contracted at one or each of the approximal sides as is found necessary, fitted, and soldered. Use of Contouring Pliers. — "Contouring" pliers are used by some to give form to a seamless crown, sufficient to knuckle it against the adjoining teeth ; but the bulge that is imparted by this means is generally located well toward the neck of the crown, instead of being close to the grinding-surface where it is required. External Application of Contour — A close knuckling of the grinding-surface of a seamless crown to that of an adjoining tooth can always be easily made by scratching the surface of the gold at the point the knuckling is desired, packing on Moss Fibre Gold or foil, and flowing a little solder over it, then fitting and trimming to the desired size and shape. To Contour on the Die with a Swager. — A seamless crown may be given contour on the swaging die in the following manner: 118 IMPARTIXG COX TOUR TO SEAMLESS GOLD CROWNS. 119 Fir,. 221). Form the die for the intended crown of a fusible metal which melts at 180° F. Reduce the neck of the die to the shape and size re- quired for the crown, which can be accurately determined by measurement with a stripof copper, or, cast a die of the exact shape from a sectional plaster mold of the tooth, formed longitudinally in halves. Place over the die a tight-fitting seamless gold cap. Mallet and burnish the gold as closely as possible to the die. If it is a bicuspid or molar, swage the grinding-surface. Place the crown in a small shot swage, as illustrated in Fig. 220, surrounded with the shot, and insert and hammer the plunger, which will cause the shot to uniformly swage the gold by de- grees closely to the die. When the swaging is completed, remove the die from the crown by placing it in holing water to melt out the fusible metal. Should any of the metal ad- here to the gold, immerse the crown in nitric acid, which will quickly dissolve it. Sectional Mold Method. — The artistic re- quirement of all gold crown-work is, that it shall reproduce the anatomical contour of the natural teeth. Such a form can be given bi- cuspids and molars by the sectional mold method more easily than by any other. For this reason it is the method adopted for the manufacture of ready-made gold seamless con- tour crowns. The sectional mold method, though a practical one for the manufacturer, will be generally found tedious for the Fig. 221. Fig. 222. Fig. 223. feJJI ; i ifill i formation of a single crown for an individual case in the hands of the ordinary practitioner. Formation. — To describe and illustrate the process we will take 120 GROWN-, BRIDGE-, AND PORCELAIN-WORK a superior molar (Fig. 22 1). A natural tooth, or one made of plaster, is used as a model. From this a sectional mold is made in Babbitt's metal, zinc, or fusible alloy, as illustrated in Figs. 222 and 223. Molds. — Flasks are now manufactured and sold to facilitate the formation of a metallic sectional mold. Fig. 224 illustrates Fig. 224. a flask of this kind, "the Turner." The form of the tooth to be molded is placed in the center, occluding surface up. The molding ring is set around the tooth form (small diameter up) and Fig. 225. the two metal strips placed inside the molding ring on each side of the tooth form, but not touching it, on a straight line from mesial to distal side. The melted fusible metal is next poured, covering the tooth form and forming the entire mold. The larger molding ring is placed around the smaller one to cool the metal. While the metal is yet slightly warm the metallic mold is taken out of the IMPARTING CONTOUR TO SEAMLESS GOLD CROWNS. 121 ring, the strips on the sides removed, and the mold split in two through the slots formed by the metal strips with the dividers shown in Fig. 225. The tooth form is next removed, the parts put together the same as before being split and set back in the small ring, and the mold is then complete. Shaping the Cap. — Into the mold a cap of gold (Fig. 226) 28 to 24 carats fine, ISTo. 28 to 30 gage, is adjusted, fitting tightly the orifice of the closed mold. The mold is placed in a vise, the cap expanded to the general form of the mold by hammering into it a mass of cotton or some other suitable material, and with a wood Fig. 226. Fig. 227 Fig. 22S. point or a burnisher revolved by the dental engine burnished into every part of the mold (Fig.. 227). To facilitate the process, the mold should be frequently opened, and the gold annealed. Fig. 228 represents the completed crown. Ready=Made Gold Crowns. — Ready-made seamless gold crowns, such as the "Evans," are made in the manner above de- scribed. They are arranged in sets of different sizes, representing the average forms generally required, with some of the usual deviations. CHAPTER X. Adjustment of Seamless Gold Crowns. expansion of the collar and crown— alteration of a side oh part of a crown— alteration of the occluding surface — contraction of the neck— to deepen the cusps — to point, lengthen, or narrow in appearance the labial cusp— to remove the indentation between cusps — strengthening and reinforcement of seamless gold crowns— method of forming a solid grinding-surface — external reinforce- ment of seamless gold in "close bites" — comparative merits of the sectional and seamless methods of con- structing gold crowns. A superior molar — one of the most difficult teeth to operate on — will serve as a typical case to illustrate the process of adjustment. The crown or root is first shaped, and, if necessary, built down with amalgam, straight, or tapering slightly on its sides toward the oc- cluding surface, as described at page 40. A crown of the proper size is specially made or selected from a ready-made stock. If the latter, its selection will be facilitated by having a plaster model of the case and a wire measurement of the neck. The croAvn is an- Fig. 229. Fig. 230. ^ A Fig. 231. nealed, slipped over the end of the root or tooth, and gently worked upward — the gold of the collar will adapt itself to the form of the root in the operation — until the edge meets the margin of the gum (A A, Fig. 229). 1. Mark a line (B) on the gold parallel with the margin of the gum. 2. Remove and trim to this line (A, Fig. 230). If necessary, repeat the marking and trimming until the edge meets the gum evenly. 3. Bevel the edge of the gold, readjust the crown and press 122 ADJUSTMEXT OF SEAMLESS HOLD C'A'OU .V.S. 123 it up until the edge of the collar passes under the margin of the gum, and, if the occlusion is correct, burnish the gold to the cervix (Fig. 231). Expansion of the Collar and Crown. — If the collar of the crown needs enlargement, it is easily and most properly accom- plished with crown expanders (shown in miniature form in Fig. 232), the points of which should he introduced at first just within the edge of the neck, and the gold spread sufficiently to allow it to fit over the end of the natural crown or root, the process of ex- pansion being gradually continued as the crown is brought into position. By proceeding in this manner too great expansion is avoided. Fig. 232. Fig. 233. Alteration of a Side or Part of a Crown. — The contour of one or both sides can be depressed and the crown thus narrowed by introducing the points of a crown expander or some tool that will fit loosely inside the crown, then steadying the crown with the fingers as shown in Fig. 234, and tapping the sides to be reduced with the flat end of a riveting hammer. Pliers will also accom- plish it, one beak being placed inside of the crown, and the other against the bulge on the outside (Fig. 233). This is necessary when the side of a crown presses on an adjoining tooth, and the crown is thus prevented from coming into proper position. To Alter the Shape of a Portion of the Collar or Side of a Crown, slip the crown over the point of an anvil, or the end of a pair of expanders, or a small round-handled instrument held in a 10 124 CROWN-, BRIDGE-, AND PORCELAIN-WORK. vise, and then tap the part to be altered with the flat end of a riveting hammer to the form desired. Alteration of the Occluding Surface — Before the crown is pressed up to its apparently proper position, the occlusion should be examined, and calculations carefully made to obviate any de- fects of articulation, which can be readily corrected at this stage by proper manipulation of the crown. Fig. 234. Fig. 235. Fig. 236. Alteration of the Grinding=Surface — Place crown in position on the tooth and flatten the part with a large gold-foil condenser tapped with the mallet, or hold the crown and tap the part as shown in Fig. 235. The closing of the antagonizing teeth upon the crown by the patient with force will aid or complete the operation of articulating. Contraction of the Neck — -To slightly contract the neck bend in the edge of the gold at the neck with narrow-beaked pliers, and holding the crown evenly and firmly between the fingers, as shown in Fig. 236, burnish the sides and neck section inward around the entire circumference of the crown. To Considerably Contract a Crown. — Slit the gold longitudinally at the palatal or lingual side its full length to the grind- ing-surface, as shown in Fig. 237, bevel off the edge to lap under, contract the crown, read- just to the tooth, remove, place the smallest quantity of solder or dampened flux solder filings in position on the seam, and then solder by holding Fig. 237. ADJUSTMENT OF SEAMLESS GOLD CROWNS. 125 in an alcohol flame, or by carefully heating in the upper section of a Bunsen flame. Xext proceed with the further adjustment of the crown. The line of the seam can be stoned off and polished after the crown has been fitted, and additionally soldered to strengthen the sides or grinding-surface. To Deepen the Cusps.- — Trim a piece of wood to the form shown in Fig. 238, rest the neck on a folded napkin, and press th" wood between the cusps. To Point, Lengthen, or Narrow in Appearance the Labial Cusp of an upper bicuspid crown, gently tap the gold on each side of the labial cusp toward the point at the angle shown in Fig. 239. To Remove the Indentation between the Cusps and thus flatten the entire grinding-surface, introduce inside The crown a Fig. 238. Fig. 239. Fig. 240. flat-ended piece of wood the size of the crown and press downward as shown in Fig. 240. Strengthening and Reinforcement of Seamless Gold Contour Crowns. — Additional strength and stiffness can be given to seam- less gold crowns, when desired, in several ways, by soldering in an open flame. The liability of melting the gold which forms the side of the crown in the operation has, with some, been one of the objections to their use. Great care must be exercised to avoid this, to which end the crown should be held in the upper sec- tion of the flame, watched, and instantly removed as soon as the solder fuses and flows. The heat should be very gradually and uniformly applied by twisting and moving the crown well up and down in the flame, so that the gold of the crown shall at no time become hotter than the solder. If this precaution is not observed the solder is apt to penetrate the gold of the crown. The crown should be held in such a position that a full view of the interior is 126 GROWN-, BRIDGE-, AND PORCELAIN-WORK. presented and the melting of the solder rendered visible; this will occur at a red heat. To stiffen the whole interior of the crown, after it has been properly adjusted, dampen the inner surface with wet cotton on the j)oint of an instrument; place in the interior a quantity of fluxed solder filings (solder filings mixed with Parr's flux or pul- verized vitrified borax) ; place the finger over the neck end of the crown, invert, and shake well. A portion of the solder filings will adhere evenly all over the wet surface. The finger is then removed and the surplus dropped back into the bottle. Catch the edge of the neck with tweezers, and heat the crown in a large alcohol or gas flame until the solder fuses, when it will flow evenly over the surface of the gold without materially altering the general form. A crown may be stiff 'ened externally by flowing a film of 22-carat coin solder over all or part of its surface. The grinding-surface of seamless crowns can be thickened by filling the interior of the cusps with solder. If considerable of the natural crown is present, the solder should be confined to the cusps, avoiding all excess, which would be liable to obstruct the read- justment of the crowns, a difficulty which often occurs and which is troublesome to correct. Method of Forming a Solid Gold Grinding=Surface with Moss Fibre Gold and Solder. — A grinding-surface of solid gold, which will be uniform in shape to that of the natural crown it is to cap and not liable to interfere with the readjustment, may be formed as follows : Dry the gold crown and place in the interior of the grinding-surface a layer of Moss Fibre Gold. Insert the crown, press to position and occlude the teeth, and remove the crown. The Moss Fibre Gold will exhibit an impression of the tooth. Add more Moss Fibre Gold until a. nearly condensed lining of it fills the grinding-surface. ISText saturate this lining of the Moss Fibre Gold with solder. This is done by applying and fusing the solder cut in very small pieces, or fluxed solder filings, on the surface of the gold, a very little at a time and in quantity only so much as the Moss Fibre will absorb. If more solder than this is applied the adjustment of the crown is liable to be obstructed. If the operation is properly performed it will result in an interior of gold that will correspond in form with that of the natural tooth. ADJUSTMENT OF SEAMLESS COLD CROWNS. ^97 External Reinforcement with Platinum and Gold in "Close Bites." — In a very close Lite when removal of only very little of the occluding surface of the tooth crowned, or of the occluding teeth, is for any reason permissible, a film of solder or 18-carax plate may be flowed over the outer surface, or a piece of perforated platinum foil of a size only sufficient to cover the occluding sur- face can be pressed or swaged to its form and closely soldered, using only a very small quantity of solder. By this latter method the grinding-surface will ocupy the least possible space and present a metallic face which will very effectually resist attrition. The platinum will absorb enough of the solder, if sufficient heat is applied, to give the grinding-surface of the crown a color resem- bling that of clasp-gold. Gold seamless crowns, especially those made of platinized gold, can be filled solid, by investing the outside surface in plaster and marble-dust, heating up the investment, placing solder, small pieces at a time, inside the crown and fusing it, by applying the full flame of the blowpipe around or underneath the investment. Seamless crowns can 1 e inserted in an easy and inexpensive manner by filling in the lower section of the crown with amalgam from which the mercury has been well pressed out instead of gold, and then cementing on the crown with oxyphosphate in the usual manner. In a case so inserted, with no antagonizing teeth, the result is the same as though the inside of the occluding surface of the crown was filled with gold; but if antagonizing teeth are present, the gold of the crown is liable to wear through in places and expose the amalgam. Altering a Gold Crown to the Exact Form of Any Corre= sponding Natural Tooth. — Keady-made gold seamless contour crowns frequently afford the means of easily and quickly perform- ing a crowning operation. In a case having nearly all the natural teeth present, in which the occluding surface and sides differ in shape from the form of the gold crown, to such an extent as to interfere w r ith its adjustment, a die of the natural crown should be made of fusible metal (Melotte's Fusible Alloy, see Part V. Ohapter III), and with it the interior of the gold crown should be altered in shape sufficiently to receive the natural crown, I>y resting the occluding surface of the gold crown on a folded napkin and gently tapping the die into it. By this means a ready- made gold crown is quickly altered to the exact shape of any tooth. 128 CROKX-, BRIDGE-, AXD PORCELAIN-WORK. Comparative Merits of the Seamless and Sectional Methods of Constructing Gold Crowns. — The seamless and sectional crown methods each possess their respective advantages for the accomplishment of the work in hand. By expertness the same effectiveness in result can generally be accomplished by either method. The constructive details of each adapt it specially to certain classes of work, wherein for this reason it is superior to the other in that it affords facilities for the accomplish- ment of the result with less labor. Thus, crowns for very short teeth of abnormal occlusion, also cases of abrasion requiring special forms of incisal and occlusal surfaces of solid metal, are generally best constructed in sections. Bicuspids and molars as well as incisors and cuspids, when all or nearly all of the natural tooth is present and the occlusion is normal, are generally con- structed to advantage by the seamless methods. CHAPTEK XL Various Forms of Gold Crowns with Porcelain Fronts. porcelain and gold crown without a collar— roots below gum- margin: special forms— cup-shaped cap: dr. van woert's method— dr. chupein's method — ready-made post and disk— dr. sanger's method— double cap-crown. Porcelain and Gold Crown without a Collar. — The root of a cuspid will be taken as a typical case to illustrate the construction of this style of crown. The end of the root is prepared the same as for a porcelain crown (Fig. 241). The root-canal is enlarged with a drill which will closely fit the opening and the orifice slightly reamed. Into the canal, gaging its full diameter, is fitted a piece of iridio- Fig. 241. Fig. 242. Fig. 243. Fig. 244. platinum wire, tapered off to a point, so that by introducing it far up the canal greater strength can be obtained, and the root rendered less liable to longitudinal fracture from pressure in a forward direction. A piece of platinum plate, a trifle larger than the end of the root, of about No. 34 gage, with a hole punched in its center, is then slipped on the post, which it must fit tightly (Fig. 242). When the post is adjusted firmly in the canal, the platinum plate is pressed down on the root, and burnished into the orifice of the canal around the post. When the post is withdrawn from 129 130 CROWN-, BRIDGE-, AND PORCELAIN WORK . the root, the platinum will adhere to it, if fitted closely, with- out the use of wax. A particle of pure gold with borax is put in the joint, and melted in a Bunsen gas flame. Barely enough of the gold should be used to unite the parts. When soldered, the post and cap are again adjusted in the mouth and the cap malleted and burnished to the form of the end of the root, so that its edge will leave a mark on the platinum. The cap, on being removed, should be trimmed to this mark, and again burnished on the root (Fig. 243). Sometimes the platinum may be slightly burnished over the edge around the palatal portion of the root. The post is then cut off just above the platinum, and a plate tooth fitted, backed, and cemented with wax in position on the cap, as described on page 88. The whole is then removed, invested, and soldered with gold, which should be melted in at the base of the post, as at this point, when in use, the strain is very great. The post is then barbed, and the crown is cemented to the root with gutta-percha, os:yphosphate cement, or both combined (Fig. 244). Roots Below Gum=Margin. — The crown just described is a suitable form for application in cases where the cervical end of the root through either decay or fracture is considerably below the surface of the gum and does not admit of the use of a collar. In such cases the end of the root should be first fully exposed by pellets of gutta-percha fastened in the orifice of the root-canal and extend- ing over the surface of the end of the root, pressing away the gum, the application being repeated as often as necessary. The above method of shaping the cap is preferable to stamping it, as sug- gested by some writers. Special Forms. — Several methods of capping are practiced in which, by giving the end and sides of the root specified forms, the use of a collar is avoided and protection against decay or fracture is promised. Cup=Shaped Cap. 1 — The root is removed to, or very nearly to the line of the gum, and the edge of the end rounded off under the gum-margin, leaving the end tapering to the orifice of the canal, as illustrated in Fig. 245. The cap is made of a disk of gold, about No. 31 or 32, or of platinum, about No. 34 gage. This is first perforated and adapted to the orifice of the root-canal, which re- quires to be slightly enlarged. The disk is then slit at the center 1 Dr. J. Rollo Knapp's method. FORMS OF GOLD CROWNS WITH PORCELAIN FRONTS. 131 of the palatal side and slightly lapped (A, Fig. 246), and then again fitted to the end of the root and closely adapted to its surface and margin, which the lapping over of the slit easily permits. The edges are then united with the least possible quantity of solder. The edges of the cap, guided by several adjustments, are trimmed even with the sides of the root and the post soldered in position. B, Fig. 246, shows the cup-shaped cap with post ready for the ad- justment of the porcelain front, which is attached in the usual manner. Dr. F. T. Van Woert, in constructing crowns without collars, shapes the end of the root, and adapts the cap, as shown in Fig. 247. The slant given to the palatal side aids the root to resist force in a forward direction. Partial Collar Crowns. — The advantages of a collar can in a Fig. 245. Fig. 246. Fig. 247. Fig. 248. A great measure be given these forms of post or dowel crowns by the addition of a metal flange encircling the palatal section of the root, as shown in Fig. 248. A piece of gold or platinum, similar in shape to that shown at A, is formed and fitted to the crown, fixed in position on the crown with wax, and adjusted in the mouth against the surface of the neck of the root, removed, in- vested, and soldered. After finishing, the metal flange is bur- nished against the root before the crown is cemented. Dr. T. F. Chupein's method to form a partial collar-cap for a root is : Cut a strip of platinum of about No. 32, or gold plate of No. 30 gage, to the shape shown in Fig. 249, for instance, for an incisor. Bend the metal to the form illustrated in Fig. 250. Place the collar on the root with the broad portion at the labial side. Grasp the ends with pliers and draw the metal tightly to- 132 CROWN-, BRIDGE-, AND PORCELAIN-WORE. gether against the sides. Remove and solder the ends together (Fig. 251). Trim the edge of the collar to the surface of the root. Solder on a thin piece of platinum plate to form the cap (Fig. 252), and remove the surplus plate and projecting ends and the labial section of the collar (Fig. 253). The cap is then ready to have the post fitted and soldered to it in position (Fig. 254). As the labial section of the collar assists in determining the exact relation of the cap to the root, it is best in some cases not to remove that portion until after the post is soldered. Fig. 249. Fig. 250. Fig. 251. Fig. 252. Fig. 253. Fig. 254. Post and Disk Method. — Ready-made posts corresponding in size to the Ottolengui reamers, Fig. 96, with prepared disks of platinum, can be used to facilitate the construction of crowns of this style. The posts are illustrated in Fig. 257. A disk of platinum with Fig. 255. a perforated depression in which a little pure gold has been melted is shown in Figs. 258 and 259. The method is as follows : Shape the surface of the end of the root as shown in Fig. 255. Trim the approximal and palatal sides of the end of the root as illustrated in Fig. 256, but leave the labial side A, intact. Enlarge and ream the root-canal with Ottolengui root-canal reamers, shown in Fig. 96, to the proper depth, first using the smallest size, and if necessary the larger sizes afterward. Select a post (Fig. 257) corresponding in number to that of the FORMS OF GOLD CROWNS 1 \YITH PORCELAIN FRONTS. 133 reamer used. Seize the large end of the post with the points of the pliers and fit the post to the canal. Move the post up and down — but do not twist — a few times in the canal, and any slight discrepancy that may exist respecting size will be instantly re- moved. Grasp the post when fitted in the canal with the pliers, having the points close to the surface of the end of the root. Remove the post without changing the relation of the pliers. Screw the post into the hole in the depression of the platinum disk, shown in Fig. 258, and in section in Fig. 259, up to the points of the pliers,- thus giving the post its position in the disk. Bend the sides of the disk downward, as shown in Fig. 260, and adjust the post in the canal to determine their relative posi- tions. By twisting the post, changes of its position in the disk may be effected, also by pressing the post further through the platinum while the disk is in position on the root. Fig. 257. Fig. 258. Fig. 259. Fig. 260. The orifice of the root-canal should be slightly enlarged with a round bur to allow the depression of the disk to fit within it. Press the post firmly upward in the root-canal to assure that its original position is not interfered with by the disk. Remove the post and disk, the disk retaining its position on the post. Unite post and disk by holding them in a Bunsen gas flame until the pure gold in the depression is fused. oSTo flux is neces- sary, as sufficient remains from the fusion of the gold in the de- pression. Place the post and disk on the root, and press and mallet the platinum to it with a large flat plugger, which, owing to the rigidity of the post in the canal, will accurately retain the platinum in position on the end of the rooL. Remove and slit the platinum at two or three points between the palatal and approximal sides to the outline of the end of the root, as shown in Fig. 261, at A and B, and bend the platinum over with the pliers to embrace the approximal sides of the root. 134 CROWN-, BRIDGE-, AND PORCELAIN-WORK. Again place the post and cap on the root, and closely fit the side flaps, with the aid of foot-shaped condensers and burnishers. Next bring the palatal flap down to position. Frequent removals and annealings are necessary during the process, which should include the final trimming of the edge of the platinum, smooth- ing with a corundum-point, and then an annealing and all-round burnishing of the cap to the root. Cut off the end of the post above the cap with a corundum-disk and level with a wheel. The Fig. 262. Fig. 263. Fig. 265. Fig. 266. Fig. 267. cap can now be invested and the seams soldered, or this can be done in the soldering on of the porcelain front. At the cervico-labial section the porcelain can rest on the plati- num, or the platinum can be trimmed, so that the front edge of the porcelain may be fitted directly against the root, and cover it. The remainder of the construction is similar to that of a full collar crown, described at page 88. FORMS OF GOLD CROWNS ^YITH PORCELAIN FRONTS.' 135 The Sanger Method. — This method, presented by Dr. K. M. Sanger to simplify the construction of the half-collar cap for crowns, is as follows : A piece of pure gold plate, gage No. 30, is cut to about the shape of Fig. 262. Being annealed, it is grasped at the straightest edge (Fig. 262, A) with a pair of clasp-benders, and hammered down to the flat end of the benders with a small riveting hammer (Fig. 263) until it assumes the shape shown in Figs. 264 and 265. With a pair of curved shears it is cut along the collar on the outside at A A, Fig. 264, and trimmed down so that the metal tongue will pass between the two free edges of the collar, as in Fig. 266. It is then placed on the root in the mouth and burnished and trimmed to fit, carefully removed and soldered along the free edges on the outside and the points cut off, result- Fig. 268. Fig. 269. Fig. 270. ing in a half-collar cap, as shown in Fig. 267. The remainder of the work is the same as in the construction of any backed and soldered crown. The Double Cap=Crown: Dr. Parr's Method. — The advantage of this form of crown is that the root is securely and permanently capped independently of the crown, which can be removed without disturbing the cap on the root. For use in crown- and bridge-work the outer cap may be made without a collar, as shown in Fig. 269, or with a partial collar, which half encircles the inner cap over the palatal portion, and tapers off from the palatal to the labial section, as illustrated in Fig. 270. The cap on the root is cemented with oxyphosphate, and the post and outer cap with gutta-percha. The root is prepared, banded, and capped without a pin, the 136 CROWN-, BRIDGE-, AND PORCELAIN-WORK. same as for a gold collar crown (A, Fig. 268). A hole is made in the cap, and a post fitted in the canal. A piece of pure gold plate or platinum is cut fully the size of the surface of the root cap. The plate is perforated in the center and the post inserted into the hole, which it should fit tightly. The post is next inserted in the canal and the plate is adapted to the surface of the root cap and around the post. Post and cap are removed and soldered to- gether, forming an outer cap, which is trimmed evenly with the edge of the root cap (B, Fig. 268). The porcelain tooth, C, to form the crown, is fitted and soldered to the outer cap. When finished, the crown is cemented in position with gutta-percha, as shown in Fig. 269. A double cap-crown with detachable or removable crown post, for use in connection with detachable or removable bridges, is de- scribed in Part III, Chapter XL CHAPTER XII. Setting All-Porcelain Crowns on Capped Roots. the logan : dr. white's method— collar-cap— a simple method —the davis crown on a capped root. The Logan Crown. 1 — Prepare the end of the root and the canal in the usual manner and adjust in proper position a Logan crown. Grind the palatal side of the base of the crown so as to give it the slant shown in A and B, Fig. 271. Take a disk of platinum foil 1/1000 to 1/500 in thickness, push the pin of the crown through it, adjust the foil closely to the base of the crown, and secure it with wax cement, as seen in Fig. 272. Fig. 272. Fig. 273. Fig. 274. Fig. 275. Trim the platinum disk to the edge of the base of the crown so there will be no overlapping. Next place a small ball of wax on the platinum around the pin and over this wax another disk of platinum foil (Fig. 273). Heat the foil, to cause adhesion of the wax, by rubbing a hot instrument over its surface, and chill in water. Insert the post of the crown in the root and press the crown to position and occlude the teeth to positively assure its correctness. The pressure of the wax against the foil shapes it to the exact form of the surface of the end of the root. Remove and trim the second platinum disk to the outline of the root (Fig. 274). If the palatal side of the root is trimmed so that it stands a little 1 Dr. Gordon White's method. 137 138 CROWN-, BRIDGE-, AND PORCELAIN-WORK. above the gum line, the surplus platinum at that part may be slit, lapped, and burnished around this exposed portion to form a partial band. The wax is next dried with bibulous paper, the sides properly shaped, and then covered with two triangular pieces of platinum (Fig. 275). Attach the platinum to the wax by rubbing a hot in- strument over its surface, and invest the crown. When the invest- ment is set, wash the wax out with boiling water. Heat the invest- ment and flow solder in between the two pieces of platinum and finish in the usual manner. Porcelain may be substituted for gold in the construction by this method. In such a case, the disk of platinum next to the crown is not used, the wax being placed on the base of the crown. The crown should be invested and the plati- num fastened to the post with a particle of pure gold to retain it in position while the triangular space is filled with porcelain body and baked (Part IV, Chapter VI). CoIIar=Cap. — The end of the root is prepared, a gold collar fitted, and the collar capped with platinum foil 1/1000. The cap is adapted to the surface of the end of the root, punctured, and burnished to the orifice of the canal. A platinum disk Fig^TG. j s next perforated and fitted to the base of the Logan crown, the same as in the method previously described, with which the remainder of the operation is identical (Fig. 276). A Simple Method. 1 — Shape the end of the root for a collar-cap, and bevel it off at the cervico-labial section if exposure of the collar is to be avoided. Construct a collar-cap (Fig. 277). Place the cap on the root, per- forate the cap, and adapt it to the orifice of the canal. Fit a Logan crown in correct position, so that the edge of the base of the crown accurately fits the surface of the cap. llemove the crown, place zinc oxyphosphate in the countersunk section, and adjust in the mouth. When the oxyphosphate has set, remove the crown and cap and solder the pin on the inside of the cap with a very small quantity of solder, — tin and lead, — using muriate of zinc as a flux, a few blasts of the blowpipe only being required. Place the cement in the root-canal and cap and cement crown in position. Fig. 278 shows the finished crown. 1 C. S. W. Baldwin, Dental Cosmos, January, 1S87. SETTING ALL-PORGELAIN CROWNS ON CAPPED ROOTS. 139 The Davis Crown on a Capped Root. — Grind the root evenly to the gum-margin, removing al] the enamel except a little thatmay Fig. 277. Fig. 27s. Fig. 280. be allowed to remain at the palatal