Columbia ^^niucrs^itp intl)f(£ttpofHrtnfork CoIIese of ^tpsicians anb ^urgtons Hifararp Digitized by the Internet Archive in 2010 with funding from Open Knowledge Commons http://www.archive.org/details/fillingrootcanalOOweld ^ -^ ^^ ^ c <- <-^< ^ iF :y. /rr//7/y.- " If one does things well, though his home be in a wilderness, a beaten path will, by and by. be trodden to his door." rillinc) Poof Ccincils THE AID or DIAGRAMS AND CHEMICALS GcoRGi: w. Weld, a\.d.,d.d.5., NEW \OQ\\ KARJES & 532 SIXTH AVENUE -PR ICE, ONE DOLLAR . U'45' Entered according'to Act of Congress in the year iSgy By George W. Weld. M.D.,D.D.S., in the office of the Librarian of Congress, at Washington. PREFACE. ■n^HE few diagrams, that may be of aid in finding tlie entrance to difficult root canals, were originally embodied in a lecture given to the students of the New York Dental School in March, and, at a later period, at the Annual Meeting of the Seventh District Society of the State of New York. The author has received so man}- complimentary letters both from students and practitioners, stating in effect, "We never knew how easily difficult root canals could be disinfected and filled until we adopted your ideas," that he is prompted to ofTer them to the profession, together with the queries and answers relating to the Chemico-Metai,i,ic Method. SYNOPSIS. PAGrr Illustrations 7 Diagrams for Inferior Molars 8 Diagrams for Superior Molars 10 Diagrams for Bicuspids 11 Filling Root-Canals by the Aid of Chemicals 13. Dr. Schreier's Method 13 Dr. Barker's Method 14 Dr. Calahan's Method 14 The Author's Method 14 Dr. Perry's Method 15 Chemistry of the Chemico-Metallic Method i6 Actionof Nitro-hydrochloric Acid — Dental 16 Formation of "Albuminates'' 16 Nature of Gases Generated 16 Energy of Acids upon Points 17 Permanency of Asepsis 17 If Point be pushed through Apical Foramen iS If Gas should go through Foramen iS Filling Canals where there is Inflammation 19' Filling by first putting Broach into Acid ig Necessity of Extirpating the Dead Pulp 19 Filling Immediately [9 Filling with an Exposed Pulp 19 Length of Time Method in Use 20 Filling followed by Extraction 20 Blind Abscess 20 Root Disturbance following Operation 20 Disinfecting the Dental Fibrillse 21 Discoloration 22 Balsam of the Desert 22 Phosphate and Carbonate of Lime 12 Other Chemicals , 23 PRACTICAL . SCIENTIFIC —View of superior molar disin- fecled iiiifl filled bv the Chem- ico-rietallic net'hod. Rouls filed away showing metal, al- ijuniinate, etc. ; time ot oper- putrpscent j>uli> in the buccal root canals not extracted. Photographed from the orig- inal tooth. Harjes & Wright, New York. A. — Anterior view of anterior root of lower molar with two nei've canals disinfected and filled by the Chemico - rietaliic Hethod ; root filed away, showing metal, albuminate, etc. lime ot i three minutes ; pulp in canals not" extracted Photographed from the orig iiial tooth. Harjes & Wright, New York. ■;k- 'V^ ill Sup cri"- ,:!!,, ,.i,id with two canals and two foramens; time r»f operation, three Photographed from original tooth — H. & W., New York. Bayonet-shape superior ' bicuspid, showing adaptation of metal- lic broach to the curvature of root : time of operation, Photographed from original tooth— H.& W., New York. Sup ^r bicuspid with- foramen and two delicate, hair - like canals converging ; time of operation, three minutes. Photographed from' original tooth— H. & W., New York. . . . PERFECT DELICATE . . . The method pre-supposes, as a rule, no loss of tooth sub- stance ; that wherever one of the finest Donaldson Steel Broaches can be introduced into a root canal, whatever its length, whether straight or tortuous, whether filled with semi- devitalized matter, or putrescent pulp and fetid gases, that canal can be disinfected and filled within a period of five minutes ; that the chlorine gas employed tends to disinfect the dentinal fibres in the roots, assuring permanency of asepsis. (7) DIAGRAMS TO AID THE STUDENT IN FINDING THE ROOT=CANALS IN SEMI-DEVITALIZED TEETH. Inferior Molars. The anterior root oi an inferior molar has, almost invaria- hly, two small canals converging towards one foramen ; some- times, however, there are two foramens. The posterior root, as a rule, has one large canal ; sometimes a slit or ribhon-shaped canal; sometimes two canals, corresponding with the canals in the anterior root. Let Fig. A represent the usual variety of root canals of the inferior molars; the crown having been cut off near the margin of the gum, a cross section of the tooth is brought to view. Fig. a. a represents the large posterior canal in the posterior root; i, d, the two anterior canals in the anterior root. If connecting lines be drawn between the three dots, we find that we have, as shown in Fig. B, an equilateral triangle, with the base of the triangle near the anterior portion of the tooth, and the entrance to the canals at each angle. Fig. B. Fig, C is the same as Fig. B with the addition of a hori- zontal line, which indicates a "slit" or ribbon-.shaped canal. Fig. C. The entrance to the posterior canal is. however, always to be found at the apex of the triangle. When the posterior root has two canals, the diagram is changed to a square, as seen in Fig. D, and the entrance to the canals is to be found at each corner of the square. Fig. D. When the two roots descend from near the centre of the tooth the square is changed to a parallelogram, as seen in Fig. G, and the entrance to the canals will be found at each corner of the parallelogram. Fig. G. In gaining entrance to the canals in the anterior root, it is necessary that the student should bear in mind the importance of knowing the//;/ i'(y'(7//ir6)a(// to the canals, forit is oftentimes possible to introduce a fine, smooth broach when it is impossible to introduce a broach with a single hook or a number of hooks. Fig. H is a photograph of the anterior canals of an inferior molar, with smooth broaches inserted, showing the sinuosity of the canals. It will be observed that the line of approach to the buccal canal is from behind forward at an angle of 45 degrees, and from within outward at an angle of about 60 degrees. How is it possible to enlarge such a canal, with such an environment with anj' kind of a drill ? The line of approach to the lingual canal is from without in an inward direction. Such canals can be disinfected and perfectly filled by the Chemico-IMctallic Method in a very short space of time, and at the first sitting. Superior Molars. As a rule the palatine root canal of superior molars is easy of access, large enotigh to admit of a barbed broach, and the thorough extirpation of the pulp. It is an exception to the rule if abscesses form upon this root. It is the delicate, tortu- ous, buccal root- canals, containing a small quantity of dead animal matter and mephitic gases, and into which it is impos- sible to introduce barbed broaches, that create root disturbance, and finally ulceration. Fig. I represents a cross section of a right superior molar at or near the margin of the gum. The dots represent the entrance to the canals. If connecting lines be drawn between the dots we find, as observed in Fig. J, that we have Fig. J. an oblique triangle with the apex at the palatini portion of the /. tooth, and the base near the buccal side ; the hypiatcnuiia being longer at the anterior cervical portion places the posterior apex of the base near the buccal and posterior central portions of the tooth; the entrances to the canals are found at the points of the triangle. (10) Fig. K is a photograph of a right upper molar. The line of approach is .shown bj- smooth broaches inserted into the three canals. Thus we observe that the line of approach to the pala- FiG. K. tine canal is from without in an inward direction at an angle of about 45 degrees; the line of approach to the anterior buccal canal is from behind in a forward and outward direction at an angle oftentimes of more than 60 degrees; that of the posterior buccal canal from a perpendicular, slightly backward and out- ward direction; the simiosity of the canals, of course, varj-ing in different roots. Of all the root canals in the molars, the anterior buccal canal of a superior molar is probably one of the most difficult to disinfect and fill. This is, in part, due to the line of approach, which as above stated is sometimes at an acute angle from be- hind in a forward and outward direction, and, in part, because the canal is extremely delicate and tortuous. Bicuspids. The bicuspid teeth present a variety of root canals. The large, straight root, with one canal ; two small roots, with two small canals ; one root with one foramen, with two tortuous hair-like canals converging ; one root with two foramens and two tiny canals. As in the case of the other teeth where the root is straight and the- canal large enough to introduce a barbed broach, ther& is but little diflBculty in the way of extir- (II) pating the pulp and disinfecting and filling the canal, but when there are two canals, the difficulty increases in proportion to their delicacy and sinuosity. Fig. L. Fig. L., is a photograph of a right superior bicuspid with two delicate canals and two foramens. The entire tooth has been filed away on its anterior aspect, showing the pulp chamber, pulp canals, and the palatine and buccal horns of the pulp. It will be observed that the buccal horn of the pulp extends much nearer the point of the buceal cusp than the palatine horn does toward the point of the palatine cusp. This is almost invar- iably the case, and it may be said in this connection, that on this account the danger of exposing and injuring a pulp in excava- ting" a cavity is generally from the buccal side. The same rule applies to the buccal side of all the molar teeth. The liability of such an accident is lessened considerably by using on the buccal surface of such cavities, round or spoon-shaped instruments, rather than those shaped like a hatchet or hoe. The diagram, which may assist in locating the entrance to the two pulp canals of a superior bicuspid, is that of a modified dumb-bell, i.e., a line with a small ball on each end, placed in the cavity from without, in an inward and downward direction, at an angle of 45 degrees. See Fig. M. FILLING ROOT=CANALS BY THE AID OF CHEMICALS. Two opinions are held by dentists of two different schools relating to the filling of root-canals. One that they should be filled permanently and solidly, the other that they should be filled with some filling material that may be easily removed in case of root disturbance. The first plan "is based on the principle that healthy con- ditions of the tissues at the end of the fang established there is little danger of inflammation afterward occurring, and, that if it should happen, the treatment should be external and on general principles. " It has always seemed rational to believe, irrespective of the different opinions governing the proper treatment and filling of pulp canals that the enamel of a tooth is to the crown about what the shingles are to a house; and the roots of teeth, what the foundation is to a building. In filling the difficult root-canals, we are also confronted with the ideas of two different schools. On the one hand it is claimed that they should be enlarged, by the use of reamers and barbed broaches, and afterwards cleansed, disinfected and filled. On the other hand that as it is an impossibility to enlarge the delicate, crooked root-canals with instruments, or to extirpate thedead or semi-dead matter, which the}" contain, the next best and most practical method is to employ as a substitute some chemical that will coagulate the dead animal matter and correct the putrescent condition of their contents. Dr. Schreier, of Vienna, I believe was the first to introduce a method for cleansing and disinfecting root- canals by chemical means. The principle embraced by his method consists in the de- composition of the watery portion of the dead pulp fibres and the production of sodium and potassium hydrates by intro- ducing into the root-canal a combination of potassium and sodium. Dr. Schreier claims that this in connection vnth a high temperature acts as a germicide ; and that the shreds of - ' (13) the pulp left in the canal are transformed into a "soapy mass," which can be removed by a stream of water from a syringe. The last claim will doubtless hold good for the large canals, but the delicate canals would appear to be too small to admit of such a procedure. Dr. D. W. Barker's method consists in the emplo3'ment of the permanganate of potash and the perox- ide of hydrogen. Dr. Barker claims that the union of these two materials in a pulp-canal sets free the nascent oxygen. The operation is performed by introducing into the canal upon a Donaldson bristle a little of the powdered permanganate of potash, and then applying a drop of the peroxide of hydrogen. This, it is claimed, causes an intermediate change in the character of the remaining pulp tissue and the pus products. Both of these methods only provide for the disinfection of putrescent canals, the filling being an after consideration. The sulphuric acid treatment of Dr. Calahan consists in a destruc- tive process of enlarging the canals by the application of a few drops of sulphuric acid diluted with fifty per cent, water. The filling material for the same, as in the above mentioned methods, being left to the discretion of the operator. Sulphuric acid is doubtless one of the most deadly' and corrosive of all the acids. Its action is difficult to control. Under certain con- ditions, however, it appears to be harmless. For instance, when a small metallic point composed principally of zinc is immersed in strong sulphuric acid, the point is not attacked, at least, to any degree. An insoluble sulphate is formed upon the surface. The addition of water dissolves the coating and chemical action begins. But if one of the points be immersed in nitro-hydro-chloric acid, it is almost instantly dissolved. On the other hand if a napkin be laid upon a plate and sul- phuric acid poured over it, that part of the linen which is in contact with the acid, will in a short time be completely destroyed. Place another napkin in nitro hydro-chloric acid for the same length of time and the linen is not apparently injured. Thus an acid which quickly destroys a metallic substance has but little effect upon linen, and vice versa, the acid which destroys the napki n leaves the metal comparatively free from injury. The author's " Chemico-Metallic Method" consistsof the in- troduction of a smooth metallic point, composed principally of zinc into the root-canal, and the application of a drop of a (14) modified nitro-hydro-chloric acid. It is claimed, that the metallic points being extremely sensitive, neutralize the acid; that after chemical action has taken place the metallic point is corroded; that an acid albuminate is formed and the dead or semi-dead animal matter coagulated. The point is then broken off in the canal thus obliterating space, and perma- nency of asepsis is assured by the chemical action which takes place in the root-canal. Whichever one of the above mentioned methods is the most practicable, which one presents the least obstacle for usefulness in every indicated case, must be left to time and the experience of the intelligent dentist. The application of any chemical is intended, as a rule, only for the delicate tortuous canals, that will not admit of the introduction of a barbed broach for the purpose of extirpating the putrescent pulp, nor the obliteration of space by the em- 'ploj-ment of the usual filling materials. Dr. Safford G. Perry of New York, in an able article pub- lished in the lutcynational Dental Journal, Sept. 1S95, entitled, "Which Method of Root-Canal Filling will Completely Obli- terate Space," saj'S in referring to the delicate root-canals: "Let us not deceive ourselves by believing that into such a minute hole, closed atone end and full of air, we can pump either of the materials in such a way as to obliterate space. ''With a minute opening at the end of the root for the e.scape of the air, it might be done, but in the mouth it is an impossibility The only way is to leave the instrument itself.'' Dr. Perry's method consists of the introduction into the delicate canals of a small piece of gold or platinum wire, after first smearing the same with chloro— percha. Dr. Perry's method approaches nearer the Chetnico- iifetallic IMcthod. than any other system ever presented to the profession. He doubtless obliterates space, but there can be but little if any chemical action associated with his method; none between the metal employed and the chloro-percha, and very little if any between the chloro-percha and the dead animal matter in the root-canal. (15) The Chemistry of •WELDS CHEniCO HETALLIC HETHOD," By ALFRED J. COHN, Ph. D. New York. ( 1 ) What is the action of nitro-hydrochloric ( dental ) acid, containing a gum resinous matter, upon a metallic pin composed of silver, tin and zinc ; principally zinc? All authorities are agreed in stating that when Nitric and Hydrochloric Acids are mixed, the ultimate product will be practically a solution of Chlorine gas, Nitrosyl Monochloride, NO CI, and Nitrosyl Dichloride, NO C1-, in water; these being formed, as shown in the following equation : 3H N03-f 9H Cl = 5CI+2NO Cl+NO Cl---(-6H=0. Hence metals brought into con- tact with the mixture— known by the name cf Nitro-Hydro- Chloric Acid — are converted into Chlorides, partly from the free Chlorine present, partly from the Chlorine liberated from the unstable Nitrosyl compounds; and, when an excess of the acid, more particularly when warm, is present, the higher Chlorides are formed : e. g An becomes Au CI3, Sb becomes Sb Cls, Fe becomes F'e-' Cl'\ etc. It is, however, well-nigh impossible to sa)' what further complications would be caused by the disturb- ing presence of the excess of Nitric Acid and gum-resinous mat- ter present in the Nitro-Hydrochloric (Dental) Acid; there may perhaps be Nitrates formed in small quantity along with the Chlorides, or perhaps only Nitrates of the metals mentioned. (2) Is an albuminate formed as claimed by Dr. Weld? Albumins coming into contact with Acids are known to be converted into Acid-Albuuiins, designated also by the generic name "Albuminates,'' — this appellation being, however, an im- proper one, since it would imply a compoundofAlbuminic Acids with some base, which is not the case. The action of the Nitro- Hydrochloric Acid, etc., acting upon the albuminous matter in the tooth, would no doubt result in the formation of such Acid- Albumins, with coagulation besides, and it is not at all unlikely that so-called " Albuminates " of the metals employed — that is, compounds of Albumin with the Silver, Tin and Zinc — would be formed. What is the nature of the gases generated, and does the (16) chemical action upon the dead organic matter left in a root-canal prove a powerful germicide ? The gases most likely to be formed in the root-canals, as the result of the action of the acid employed on the metals, would be Nitrous Acid and perhaps Chlorine, either or both of which would, no doubt, be thoroughly germicidal on account of their powerfully destructive effects on all organic matter. (4) Is the energj' of the acids first directed to the metallic broach inserted in the root ? Acids usually seek to combine with substances for which they have the most aflSnity, and in this case the metals would no doubt be attacked b}^ preference, although it is highly reason- able to believe that the contiguous tooth substance would be attacked to some extent too. ( 5 ) Is permanency of asepsis probable ? Where absolute absence of air is obtained, complete asepsis may be assumed to be permanent; but whether such a condition can be obtained and be made permanent in a tooth cavit}- and root canal can only be ascertained by continued experiment. ^/ , ^^- . , . ^ 7^.C^ "^^' ^ (17) QUERIES. The following queries have been propounded, from time to time, by different dentists, regarding the rationale of the pro- cess of disinfection and filling the difficult root canals, by the Cheinico-JMetallic Method. The answers are given with the sincere hope that, if there are any errors, they may lead to other enquiries which, in the end, will prove of benefit to the profession. ( 1 ) " What would be the effect if one of the broaches be pushed through the apical foramen? " A somewhat similar question was asked Stephenson, viz : " What would beco:ne of a cow- supposing it got on the railroad track in front of your engine? " Stephenson, it is said, replied that it would be bad for the cow. In the first place, there is, in the difficult root-canals oj adults, only about one in ten where the foramen is open. If an operatorlacksthedelicatesenseof touch possessed by a majority of dentists, ignores a manifestation of pain from his patient, and carelessly plunges his instrument through the apical fora- men, and permits it to remain there — well, it would be bad for the tooth. The great trouble heretofore has been to properly disinfect and fill a root-canal near the apical foramen. The possibility of going through the foramen of the difficult root- canals is very remote. (2) "Will not the gas which is formed in the canal go through the foramen and irritate the surrounding tissue ? " In the first place in a large majority of the o'/^V;/// root- canals, above mentioned the foramen is closed, at least to a great extent, which prevents the possibility of such an occurrence. In the second place the chemical action is mostly confined to the entrance of the pulp canal in the pulp chamber, but may extend half way the length of the root. For this reason it is important that the operator should /«// the bristle up and down once or twice, so that the surplus acid ma}- come in contact with the extreme end ; but it being difficult sometimes to find the entrance, the bristle should not be pulled entirely out of the canal after an entrance has once been gained. (i8) (3) " Do you advise filling the roots of teeth when there is inflammation, etc. ? " As a rule, a tooth containing a putrescent pulp and mephitic gases, partially distended, and tender to the touch with more or less pericementitis, should never be treated to any very great extent at the first sitting. Open into the pulp chamber and re- move the />«//> in tin- pulp chamber only; apply counter irritation to the gum; introduce a loose pellet of cotton into the cavity and dismiss the patient for twenty-four hours. Any attempt to extirpate the pulp in the root-canals of such teeth at the first sitting is very liable to cause more irritation, if not ulceration. Frequently an abscess can be aborted by the application of two or three leeches to the gum, at a distance of a half to three-quarters of an inch from the seat of trouble — one leech is of little use. Fill at the second sitting, having first extirpated as much of the pulp as possible. (4) "Why not first put the broach in the acid and then in- sert it into the root-canals? " For the simple reason that such a procedure would not permit of proper disinfection, or destro}- the micro-organisms in the canal. The ent^- of the acid would be wasted upon the metal and the chemical result would be ////. (5) "Can a root-canal in a tooth with an exposed pulp be filled by the Method without destroying the life of the pulp ? " Always devitalize the pulp in the usual manner before util- izing the Method. (6) " Is it necessary to extirpate the dead pulp ? " Alwaj's remove the dead pulp in the pulp chamber, and as much as possible in the root-canals that will permit of being removed with a barbed broach. (7) " Can the root-canals be filled immediately ? " Yes ; but this should be left to the discretion of the operator. (8) " Can they be filled permanently ? " Permanency is only a comparative term ; there is no such thing as absolute pennanency in anything. Read what the chemist has said in this connection. (g) "A tooth with an exposed pulp was devitalized one week ago. When one of the metallic points was inserted life was apparent at the apex. In such a ca.se can the broach be intro- duced, the liquid applied and the canal filled? " In freshly devitalized teeth there is verj- likely to be more or less sensation (if not some pain to the patient) at the apex of the pulp canals, when a broach is introduced. The acid, plus the chloro-nitrates, however, coagulates live animal matter as quick- ly as dead or semi-dead matter. I fail to see why permanency of asepsis should not be probable in such a case. See the chemis- try relating to th^ germicidal effect, etc. (10) " How long have you used the Method ? " For a period of over Xjia years. (11) " Have you ever fille 1 the roots of teeth in the mouth and afterward extracted the teeth and noted the condition ot the root-canals? " In two different cases, two superior molars were filled, and the teeth sacrificed one week later. The roots of the teeth ware filed away and the canals found to be filled to the apex of each root. The application of the peroxide of hydrogen to the exposed pulp canals showed the complete absence of pus. No trouble followed the operation in either case. (12) '■ Should a root-canal be filled where there is a 'blind abscess ' ? " No s\-stem ever was devised for filling root-canals or ever will be devised, in the writer's opinion, that will preclude the possibility of root disturbance, in some cases, after filling. Where the so-called "blind abscess" exists, or where from an internal putrid condition of the root-canal, the pericementum is in an irritable condition; a predisposition to inflame makes ulceration very probable. The condition of affairs is chronic or sub-acute. Over-medication, or the careless introduction of steel broaches into the canal, in fact, anything which adds burden to the unhealthy pericementum is very apt to lead up to an acute stage — the sequel being congestion and inflamma- tion of the surrounding tissues. (13) " Will you please give me your opinion of the follow- ing case, and inform me why root disturbance followed the operation ? " " Mr. S. A. presented himself with a right superior central, crown mostly decayed away, with dead and putrescent pulp. Filed the crown off nearly to the level of the gum, with view of inserting a Richmond crown ; removed dead pulp with barbed broach, and enlarged root-canal with engine burs. Dressed with antiseptic dressing and dismissed patient. On returning the following day. the root was found to be very tender to the touch, and the gum considerably swollen. The swelling continued for three Aays, when the gum was lanced and a large quantity of pus discharged. The patient never had any previous trouble with the tooth." (20) The fact that your patient had never experienced any pre- vious trouble with the tooth would militate greatly against the probability of an existing " blind abscess." It may be assumed that in this case the apical foramen was open and that a minute quantity of septic inattcv was pushed through the end of the root. As I have stated in answer to another and somewhat similar question the pericementu^i" of such teeth is in an inflamed condition and ready to go into hysterics on the slight- est provocation. Such root canals are often filled with a mephitic gas, which, if forced through the foramen, produces the same in- flammatory effect that is produced by septic matter. It is alto- gether likely that )Ou did too much to the tooth at the flrst sitting. If you had been content to rest after you had filed off the crown, or after you had, with a spoon-shaped instrument, scooped out a little of the putrescent pulp, dismissed your patient for twenty-four hours without introducing an instni- ment into the canal, or even dressing with cotton ; in other words, if you had first given vent to the poisonous gases pre- sumably contained in the canal, the probability is that your patient would have been saved three or four days intense suffering. Again, if, in view of the necessity of crowning at the first sitting, you had twisted a little cotton around the point of one of the sensitized bristles, dipped the same in the acid, and quickly inserted into the canal, the dead animal matter con- tained in the canal near the pulp chamber would have been coagulated, and the mephitic gases eliminated with the newly- formed gases generated by the action of the acid upon the zinc. Had you then repeated the operation carrying the bristle nearly to the apical foramen, the chances of root disturbance would have been about one in a hundred. (14) " Does the Chemico-Metallic Method for filling root- canals disinfect the dead animal matter, or the so-called &^n- Xinaljibnllae in the roots? " To understand the rationale of the process of disinfection by the Chemico-Metallic Method, bear in mind that one of the principal factors in producing asepsis is the chlorine gas with which the acids are charged, or which is formed by the chemical action of the acids upon the metallic points. Both nitrous and chlorine gases are powerful germicides, and when generated in a root-canal must, at least, to some extent, permeate the dentinal tubuli and disinfect the dead dental fibres. • (21) It miy hi observed in tliis connection, however, that if the pulp in a pulp canal be completely removed, before putrefaction sets in, the chances of irritation or root disturbance will be very remote. The palatine root-canal of the superior molar, which is easy of access, favors the complete removal of the pulp, and seldom gives trouble. It is upon the attenuated, trirtuous roots of molars which abscesses usually form. (15) ' ' Please inform me if there is any danger of discolora- tion in using the Method ? " No. How can there be, when the points are composed principally of zinc, and the generation of chlorine gas a factor ? If anytliing, the Method tends to bleach, rather than discolor. (16) "Will you kindly inform me if, before introducing into the root-canals your points, it will answer the same pur- pose if I smear them with the ' balsam of the desert ' ? " Imitation is the sincerest form of a compliment. ' 'Balsam of the desert" has no chemical action on the metallic points; it does not prevent a putrefactive condition. li is not a germ- icide. To utilize the points without the application of the liquid chemicals would have its parallel in the pla}' of 'Ham- let," with Hamlet left out. (17) " Please inform me how it is that a tooth composed of the phosphate and carbonate of lime, which I have always supposed to be sensitive to the action of acids, is not attacked and dissolved before the metallic points as claimed b}^ you? " This is a question which a chemist should answer, and I refer you to the Chemical Query, number 4, answered by the chemist. If you will take the trouble, however, to drop a small piece of the enamel of a tooth into the dental acid, and then a small piece of one of the metallic points, you will be convinced that the former is more resistant to the action of the acids than the latter. The question arises whether the nascent chlorine gas which is generated in the pulp canal, plus the influence of the acid, tends to a slight loss of tooth substance, and the formation of lime phosphates around the metallic point. It is known that chlorine has but little attraction for oxygen, its energies being principally exerted towards hydro- gen and the metals. In this connection it may be again observed that the metallic points are composed principally of zinc, which is one of the most susceptible of metals to the -action of acids. ^ '22) ( iS) " Please inform me if there is not some other chemi- cal that will answer the same purpose and be substituted for the acids you employ ? " If the root-canals were large enough to admit the introduc- tion of a formaldeh^-de lamp perhaps formaldehyde would be the best substitute as a disinfectant. The Chentieo-Mctallic Method means, not only thorough disinfection, but perfect filling at the same time. It means the generation of nitrous- chlorine gas in the root- canals ; the coagulation of the dead animal matter, the formation of the so-called albuminates, and finally permanent asepsis through the influence of a powerful germicide. . {19) " Kindly inform me how j-ou would proceed to disin- fect a large putrid canal, in a root you desired to crown at the first sitting ? ' ' Insert one of the sensitized broaches into a broach-handle ; twist a I'cry little cotton around, nearh- the whole length of the broach ; bend over the point against the cotton, as the barb on a straight fish-hook might be pressed down ; dip the broach into the acid, quickly carry into root-canal, and pull up and down. Repeat this operation once cr twice, and in one minute's time the worst kind of a canal can be thoroughly dis- infected. (20) " Please inform me if it is necessary to use any alkali to neutralize the acid after it has come in contact with one of the points in a root canal ? " The points neutralize the acid. A surplus of the acid completely destroys the points ; but a single drop, although producing chemical action, only corrodes them. While at the same time it coagulates the animal matter. "Many a clever artist has failed, because in the pride of youthful facility, he has de- clined the method and drudgery of a correct technique.'^ 1 COLUMBIA UNIVERSITY LIBRARIES This book is due on the date indicated below, or at the expiration of a definite period after the date of borrowing, as provided by the library rules or by special arrangement with the Librarian in charge. DATE BORROWED DATE DUE DATE BORROWED DATE DUE C2B(946)MIOO COLUMBIA UNIVERSITY LIBRARIES (hsUlxl RK 541 W45 C.1 EilluiQ ;ool canals bv the aid ol diaqfa 2002446901 W45 HHS^t wy^vT liiiiiii