TIN FOIL AND ITS COMBINATIONS FOR FILLING TEETH. 

 BY HENRY L. AMBLER, M. S. , D. D. S. , M. D. , Professor of Operative Dentistry and Dental Hygiene, in the Dental Department of Western Reserve University. Member of the American Dental Association; of the Ohio State Dental Society; of the Northern Ohio Dental Association; of the Cleveland City Dental Society. 

 PHILADELPHIA: THE S. S. WHITE DENTAL MFG. CO. , LONDON: CLAUDIUS ASH & SONS, Limited. 1897

 Copyright, HENRY L. AMBLER, 1896. All rights reserved. Entered at Stationers Hall, London. 

Transcriber's Note:

 Minor typographical errors have been corrected without note. Variant and obsolete spellings, particularly chemical terms, have been retained. The oe ligature is represented by [oe]. Subscript characters are shown _{thus}, for example H_{2}O. 

PREFACE. 

Believing that sufficient and well-deserved prominence was not beinggiven to the use of tin foil and its combinations, the author decided topresent a brief historical résumé of the subject, together with suchpractical information as he possesses, before the profession in orderthat it may have the satisfaction of saving more teeth, since that isthe pre-eminent function of the modern dentist. One object is to meetthe demand for information in regard to the properties and uses of tinfoil; this information has been sought to be given in the simplest formconsistent with scientific accuracy. The present use of tin is a case ofthe "survival of the fittest, " because tin was used for filling teethmore than one hundred years ago. There is not a large amount ofliterature upon the subject, and no single text-book has treated thematter fully enough to answer the needs of both teacher and pupil. It isdifficult for the student to collect and harmonize from the manydifferent sources just the kind and amount of information required forhis special use. Perhaps this work will be of assistance to scientificstudents and practical operators in the art of using tin foil, includingall who wish in compact form an explanation of the facts and principlesupon which the art is based. A good method to arouse in students aninterest in the use of tin foil is to have them use it in operativetechnics, which is becoming an effective adjunct in every dentalcollege. By this means a great factor will be brought to bear, and theresult will be that hundreds of graduates every year will beginpractice better qualified to save teeth than if they had not knownwhatever may be learned about this material. At the University ofPennsylvania, Department of Dentistry, session 1896-97, out of the totalnumber of fillings made in the clinical department (fractions omitted)55 per cent. Were gold, 15 per cent. Tin, 10 per cent. Amalgam. Thisshows that tin has some very strong friends in the persons of ProfessorsDarby and Kirk. 

The historical sketch of the development of the subject is arranged inchronological order, and is given partly to show that some old ideas andmethods were good, and some obviously incorrect when viewed in the lightof more recent developments. Part of the history will be new to theoldest members of the profession, and the younger ones will certainlyread it with interest. The work has been brought up to date byconsidering all the properties and methods available. More names, goodopinions, and dates could have been given, but the writer believes thatwhat is herein presented is enough to thoroughly substantiate his ownopinions, experiments, and practical applications. Some of theillustrations have been made especially for this work; the others havebeen obtained through the courtesy of the owners. 

"Let not the foggy doctrine of the superiority of gold in all cases acton progress as the old medieval superstitions acted on astronomy, physiology, zoology. Truth sought after without misgiving, and thehumblest as well as the highest evidence taken in every case, and actedon with skill and discrimination, will crown all with a high average ofsuccess. "

It is hoped that what has been said in this volume will enable those whostudy it to save more teeth, and stimulate them to make improvements onthe material and methods, doing much better than has been described orsuggested. 

CLEVELAND, OHIO, June, 1897. 

 "With soft and yielding lamina, and skill, The practiced dental surgeon learns to fill Each morbid cavity, by caries made, With pliant tin; when thus the parts decayed Are well supplied, corrosion, forced to yield To conquering art the long-contested field, Resigns its victim to the smiles of peace, And all decay and irritation cease. " (_Solyman Brown. _)

The quantity of tin foil used measures the number of teeth saved with_metals_ in any country during any historical period. 

CONTENTS. 

 CHAPTER I. PAGE Antiquity of Tin--Alchemistic Name--Medical Use--Where Found-- Purity Obtained--Physical Characteristics 1

 CHAPTER II. History of the Use of Tin Foil, 1783-1844 7

 CHAPTER III. History Continued, 1845-1895 15

 CHAPTER IV. Columbian Dental Congress--Opinions on Tin Foil--Reasons for Using--Manufacture in United States--Number and Weight of Foil--Cohesion--Good Qualities of Tin Foil--Temporary Teeth-- Thermal Changes--Calcification--Chalky Teeth 27

 CHAPTER V. Discoloration of Tin--Decomposition of Food--Sulfids--Oxids-- Galvanic, Therapeutic, and Chemical Action 40

 CHAPTER VI. White Caries--Gold and Tin as Conductors--Wearing Away of Fillings--Poor Foil--Buccal Cavities--Number of Years Fillings Last--Strips or Tapes for Filling--Number 10 Foil-- Form of Cavities--Shields--Matrices--Condensing--Finishing-- Cervical Margins--Filling Anterior Teeth--Lining with Gold 49

 CHAPTER VII. Filling, part Tin, part Gold--Cervical Margin Liable to Caries--Electrolysis--Hand Pressure--Hand Mallet--Tapes and Ropes Compared--Manner of Preparing Foil--Starting the Filling--Cylinders--Mats--Facing and Repairing--Tin Shavings--Dr. Herbst's Method--Fees 56

 CHAPTER VIII. Dr. Robinson's Fibrous and Textile Metallic Filling--Tin and Gold combined (Tg), Methods of Preparing and Using--Lining Cavities with Tin--Tin and Amalgam--Plastic Tin--Stannous Gold--Crystal Tin--Filling Root-Canals--Tin and Watts's Sponge Gold--Capping Pulps 66

 CHAPTER IX. Temporary Fillings--Sensitive Cavities--Integrity--Tin with Sponge, Fibrous, and Crystallized Gold--Tin at Cervical Margin--Filling Completed with Gold--Gutta-Percha and Tin-- Occlusal Cavities with Tin and Gold--Comparison of Gold with Tin--Wedge-shaped Instruments--Old Method of Using Rolls, Ropes, Tapes, or Strips--Later Method--Filling with Compact and Loose Balls--Cylinder Fillings--Operative Technics 91

CHAPTER I. 

Moses, who was born 1600 B. C. , mentions tin, and history records its use500 B. C. , but not for filling teeth; much later on, the Ph[oe]nicianstook it from Cornwall, England, to Tyre and Sidon. 

The alchemistic name for tin is Jove, and in the alchemisticnomenclature medicinal preparations made from it are called Jovialpreparations. 

Hindoo native doctors give tin salts for urinary affections. Monroe, Fothergill, and Richter claim to have expelled worms from the humansystem, by administering tin filings. 

Blackie, in "Lays of Highlands and Islands, " referring to tin as money, says, --

 "And is this all? And have I seen the whole Cathedral, chapel, nunnery, and graves? 'Tis scantly worth the tin, upon my soul. "

"Tin-penny. "--A customary duty formerly paid to the tithingmen inEngland for liberty to dig in the tin-mines. 

In 1846, Tin (Stannum, symbol Sn) was found in the United States only atJackson, N. H. Since then it has been found, to a limited extent, inWest Virginia and adjoining parts of Ohio, North Carolina, Utah, andNorth Dakota. The richest tin mines of the world, however, are inCornwall, England, which have been worked from the time of thePh[oe]nician discovery. 

The tin which is found in Malacca and Banca, India, is of great purity, and is called "Straits Tin" or "Stream Tin. " It occurs in alluvialdeposits in the form of small rounded grains, which are washed, stamped, mixed with slag and scorić, and smelted with charcoal, then run intobasins, where the upper portion, after being removed, is known as thebest refined tin. Stream tin is not pure metallic tin, but is the resultof the disintegration of granitic and other rocks which contain veins oftinstone. Banca tin is 99. 961 parts tin, 0. 019 iron, 0. 014 lead in 100parts; it is sold in blocks of 40 and 120 pounds, and a bar 0. 5 meterlong, 0. 1 broad, 0. 005 deep can be bent seventy-four times without beingbroken. Subjected to friction, tin emits a characteristic odor. 

Tin in solution is largely used in electro-metallurgy for plating. Puretin may be obtained by dissolving commercial tin in hydrochloric acid, by which it is converted into stannous chlorid; after filtering, thissolution is evaporated to a small bulk, and treated with nitric acid, which converts it into stannic oxid, which in turn is thoroughly washedand dried, then heated to redness in a crucible with charcoal, producinga button of tin which is found at the bottom of the crucible. 

Pure tin may be precipitated in quadratic crystals by a slight galvaniccurrent excited by immersing a plate of tin in a strong solution ofstannous chlorid; water is carefully poured in so as not to disturb thelayer of tin solution; the pure metal will be deposited on the plate oftin, at the point of junction of the water and metallic solution. 

In the study of tin as a material for filling teeth, we have deemed itexpedient to consider some of its physical characteristics, in orderthat what follows may be more clearly understood. 

Tin possesses a crystallized structure, and can be obtained inwell-formed crystals of the tetragonal or quadratic system (form rightsquare prism), and on account of this crystalline structure, a bar oftin when bent emits a creaking sound, termed the "cry of tin;" the purerthe tin the more marked the cry. 

The specific gravity is 7. 29; electrical state positive; fusing point442° F. ; tensile strength per square inch in tons, 2 to 3. Tensilestrength is the resistance of the fibers or particles of a body toseparation, so that the amount stated is the weight or power requiredto tear asunder a bar of pure tin having a cross-section of one squareinch. 

Tenacity: Iron is the most tenacious of metals. To pull asunder an ironwire 0. 787 of a line in diameter requires a weight of 549 lbs. To pullasunder a gold wire of the same size, 150 lbs. ; tin wire, 34 lbs. ; goldbeing thus shown to be more than four times as tenacious as tin. (Fractions omitted. )

Malleability: Pure tin may be beaten into leaves one-fortieth of amillimeter thick, thus requiring 1020 to make an inch in thickness. Miller states that it can be beaten into leaves . 008 of a millimeterthick, thus requiring 3175 to make an inch in thickness. Richardson saysthat ordinary tin foil is about 0. 001 of an inch in thickness. 

If the difficulty with which a mass of gold (the most malleable ofmetals) can be hammered or rolled into a thin sheet without being torn, be taken as one, then it will be four times as difficult to manipulatetin into thin sheets. 

Ductility: If the difficulty with which gold (the most ductile ofmetals) can be drawn be taken as one, then it will be seven times asdifficult to draw tin into a wire. At a temperature of 212° it hasconsiderable ductility, and can be drawn into wire. 

Among the metals, silver is the best conductor of heat. If theconductivity of silver be taken as 100, then the conducting power ofgold would be 53. 2; tin, 14. 5; gold being thus shown to be nearly fourtimes as good a conductor of heat as tin. Among the metals, silver isthe best conductor of electricity. If its electrical conductivity betaken at 100, then the conducting power of gold would be 77. 96; tin, 12. 36; gold being thus shown to be more than six times as good aconductor of electricity as tin. 

Resistance to air: If exposed to dry, pure air, tin resists any changefor a _great_ length of time, but if exposed to air containing moisture, carbonic acid, etc. , its time resistance is reduced, although even thenit resists corrosion much better than copper or iron. 

As to linear expansion, when raised from 32° to 212° F. , aluminumexpands the most of any of the metals. Taking its expansion as 1, thatof tin would be 3, _i. E. _, aluminum expands three times as much as tin. (Dixon, "Vade Mecum. ")

Solids generally expand equally in all directions, and on cooling returnto their original shape. Within certain limits, metals expand uniformlyin direct proportion to the increase in temperature, but the rate ofexpansion varies with different metals; thus, under like conditions, tinexpands nearly twice (1-3/5) as much as gold, but the _rate_ ofexpansion for gold is nearly twice (1-7/10) that of tin. 

The capacity for absorbing heat varies with each metal; that of gold isabout twice (1-3/4) that of tin. 

Tin has a scale hardness of about 4, on a scale of 12 where lead istaken as the softest and platinum the hardest. (Dixon, "Vade Mecum. ")

Tin has a scale hardness of about 2. (Dr. Miller. )

To fuse a tin wire one centimeter in diameter requires a fusing currentof electricity of 405. 5 amperes. Up to 225° C. , the rise in resistanceto the passage of an electric current is more rapid in tin than in gold. In some minerals the current follows the trend of the crystals. 

Gold wire coated with tin, and held in the flame of a Bunsen burner, will melt like a tin wire. At 1600° to 1800° tin boils and may bedistilled. 

CHAPTER II. 

The largest and most complete dental library in the world is owned byDr. H. J. McKellops, of St. Louis. Upon his cheerful invitation, thewriter visited that "Mecca, " and through his kindness and assistance acomplete search was made, which resulted in obtaining a great portion ofthe following historical facts with reference to the use of tin indentistry:

"In 1783 I stopped a considerable decay in a large double under tooth, on the outside of the crown or near the gums, with fine tin foil, whichlasted for a good number of years. " ("A Practical and Domestic Treatiseon Teeth and Gums, " by Mr. Sigmond, Bath, England, 1825. )

"Fine tin foil or gold leaf may be injected into a cavity successfully, and retained securely for many years. " (Joseph Fox, Dover, England, 1802. )

"The statement has been made several times that tin foil was used in theUnited States for filling teeth as early as 1800, at which timedentistry began to be cultivated particularly as a science and art, andwas beginning to be regarded as of more importance than it formerly hadbeen. The writer has not found any record of its use in this countryearlier than 1809. Tin may often be employed with entire confidence. Ihave seen fillings forty-one years old (made in 1809) and still perfect. Several molars had four or five plugs in them, which had been insertedat different periods during the last half-century. I prefer strips cutfrom six sheets laid upon each other. If the foil is well connected, thecut edges will adhere firmly; if they do not, the foil is not fit foruse. " (Dr. B. T. Whitney, _Dental Register of the West_, 1850. ) Firstreference to the fact that tin is adhesive. 

"Tin is desirable in all unexposed cavities. It has a stronger affinityfor acetic, citric, tartaric, malic, lactic, and nitric acids than thetooth has: a good material where the secretions are of an acidcharacter, it is better that the filling should waste away than thetooth. One cavity in my mouth was filled with gold, decay occurred, thefilling was removed; cavity filled with oxychlorid, which produced pain;filling removed; cavity filled with gutta-percha, still experiencedpain; filling removed; cavity filled with tin, and pain ceased in anhour. A tin filling was shown in New York which was sixty years old;made in 1811. " (Dr. E. A. Bogue, _British Journal of Dental Science_, 1871. )

"I have lately been removing tin pluggings (the juices of the mouthhaving oxidated and dissolved away the metal, so as to expose the teethto decay) from teeth which I plugged fifteen years ago (1818) for thepurpose of re-stopping with gold, and have in almost every instancefound the bone of the tooth at the bottom of the pluggings perfectlysound and protected from decay. " (J. R. Spooner, Montreal, 1833. )

In 1800 the number of dentists in the United States was about onehundred, and many of them were using tin foil for filling teeth. 

In 1822 tin was employed by the best dentists, with hardly an exception;it grew in favor, especially for large cavities in molars, and for acheaper class of operations than gold, but tin was not generally useduntil 1830. ("History of Dental and Oral Science in America. ")

"Lead, tin, and silver corrode and become more injurious than theoriginal disease, and will in every case ultimately prove the cause ofdestruction to the tooth, which might have been preserved by propertreatment. " (Leonard Koecker, 1826, and "New System of Treating theHuman Teeth, " by J. Paterson Clark, London, 1829 and 1830. )

"Tin in situations out of reach of friction in mastication, as betweentwo teeth, is like the tooth itself apt to be decomposed by acidityunless kept very clean. " ("Practical and Familiar Treatise on Teeth andDentism, " J. Paterson Clark, London, 1836. ) Refer to what the sameauthor said in 1829. 

"Tin is used as a plugging material. " ("The Anatomy, Physiology, andDiseases of the Teeth, " by Thomas Bell, F. R. S. , London, 1829. )

"Silver and tin foil, although bright when first put in a cavity, verysoon change to a dark hue, resembling the decayed parts of the teethwhich are of a bluish cast; besides this, they are not sufficiently pureto remain in an unchanged state, and frequently they assist in thedestruction of a tooth instead of retarding it. " ("Familiar Treatise onthe Teeth, " by Joseph Harris, London, 1830. )

"Tin is objectionable on account of rapid oxidation and being washed bythe saliva into the stomach, as it may materially disorder it; thefilling becomes so reduced that the cavity in which it has been insertedwill no longer retain it, and acid fruits influence galvanic action. "("Every Man his Own Dentist, " Joseph Scott, London, 1833. )

In 1836 Dr. Diaz, of Jamaica, used tin foil for filling teeth. 

"Gold is now preferred, though tin, from its toughness when in the leaf, is perhaps the most suitable. Americans are superior to British infilling. " ("Plain Advice on Care of the Teeth, " Dr. A. Cameron, Glasgow, 1838. )

[Illustration: FIG. 1. ]

[Illustration: FIG. 2. ]

"Tin foil is used for filling teeth. " (S. Spooner, New York, 1838, "Guide to Sound Teeth. ")

In 1838 Archibald McBride, of Pittsburg, Pa. , used tin for fillingcavities of decay. 

The following facts were learned from Dr. Corydon Palmer: E. E. Smith, who had been a student of John and William Birkey, in Philadelphia, cameto Warren, Ohio, in 1839, and among other things made the first goldplate in that part of the country. In operating on the anterior teeth, he first passed a separating file between them, excavated the cavity, and prepared the foil, _tin_ or gold, in tapes which were cuttransversely, every eighth of an inch, about three-quarters of the wayacross. Fig. 1 shows the size of tape and the manner of cutting. With aninstrument (Fig. 2) he drew the foil in from the labial surface, usingsuch portion of the tape as desired. 

The instrument from which the illustration was made was furnished by Dr. Palmer, and is shown full size. Instruments for use on posterior teethwere short and strong, with as few curves as possible; no right and leftcutters or pluggers were used, and none of the latter were serrated, buthad straight, tapering round points, flat on the ends, and of suitablesize to fill a good portion of the cavity. He used what was termedAbbey's chemically pure tin foil, forcing it in hard, layer uponlayer, --as he expressed it, "smacked it up. " In this manner he made tinfillings that lasted more than thirty years. 

In 1839 Dr. Corydon Palmer filled teeth with tin foil, also linedcavities with gold and filled the remainder with tin. In the same yearhe filled crown (occlusal) cavities one-half full with tin and the otherhalf with gold, allowing both metals to come to the surface, on the sameplan that many proximal cavities are now filled. (See Fig. 3, showingabout one-half of the cavity nearly completed with tin cylinders. Thesame plan was followed when strips, or ropes, were used. )

"I filled cavities about two-thirds full with tin, and finished withgold. " (S. S. Stringfellow, _American Journal of Dental Science_, 1839. )

"Tin foil is greatly used by some American dentists, but it is not muchbetter than lead leaf. " ("Surgical, Operative, and MechanicalDentistry, " L. Charles De Londe, London, 1840. )

[Illustration: FIG. 3. ]

"In 1841 there were about twelve hundred dentists in the United States, many of whom were using tin, and there are circumstances under which itmay be used not only with impunity, but advantage, but it is liable tochange. " (Harris. )

"I put in tin fillings, and at the end of thirty years they were badlyworn, but there was no decay around the margins. " (Dr. Neall, 1843. )

In 1843 Dr. Amos Westcott, of Syracuse, N. Y. , filled the base of largecavities with tin, completing the operation with gold. 

"Tin is used in the form of little balls, or tubes, but folds arebetter; introduce the metal gradually, taking care to pack it so that itwill bear equally upon all points; the folds superimpose themselves oneupon the other; thus we obtain a successive stratification much moreexact and dense, and it is impossible there can be any void. " ("Theoryand Practice of Dental Surgery, " J. Lefoulon, Paris, 1844. )

CHAPTER III. 

"Besides gold, the only material which can be used with any hope ofpermanent success is tin foil. Some dentists call it _silver_, and atooth which cannot be filled with it cannot be filled with anything elseso as to stop decay and make it last very long. It can be used only inthe back teeth, as its dark color renders it unsuitable for those infront. When the general health is good, and the teeth little predisposedto decay, this metal will preserve them as effectually perhaps as gold;but where the fluids of the mouth are much disordered it oxidizesrapidly, and instead of preserving the teeth rather increases theirtendency to decay. " (Dr. Robert Arthur, Baltimore, 1845, "A PopularTreatise on the Diseases of the Teeth. ")

The false idea that a patient must have good health, normal oral fluids, and teeth little predisposed to decay, or else if filled with tin thedecay would be hastened, originated with a German or English author, andhas been handed down in works published since early in 1800. It evencrept into American text-books as late as 1860, the authors of which nowdisbelieve it. 

"Tin undergoes but little change in the mouth, and may be used withcomparative safety. " ("Surgical, Mechanical, and Medical Treatment ofthe Teeth, " James Robinson, London, 1846. )

"Tin is soft, and can be easily and compactly introduced, but it is moreeasily acted on by the secretions of the mouth than gold and is lessdurable, but in the mouth of a healthy person _it will last for years_. Still, inasmuch as it cannot be depended on in _all_ cases, we are ofthe opinion that it should _never_ be employed. " ("The Human Teeth, "James Fox, London, 1846. )

The italics are ours. Every metal has a limited sphere of usefulness, and it should not be expected that tin will contend single-handedagainst all the complicated conditions which caries presents. 

"Of all the cheaper materials, I consider tin the best by far, andregard its use fully justifiable in deciduous teeth and in largecavities, as it is not every man who can afford the expense of nineleaves of gold and four hours of labor by a dentist on a single tooth. "(Dr. Edward Taylor, _Dental Register of the West_, 1847. )

"I consider tin good for any cavity in a chalky tooth: it will save thembetter than anything else. " (Dr. Holmes, 1848. )

"Tin can be used as a temporary filling, or as a matter of economy. Itmay be rendered impervious to air and dampness, but it corrodes in mostmouths, unless it comes in contact with food in chewing, and then itrapidly wears away; it does not become hard by packing or underpressure, and that it forms a kind of a union with the tooth isridiculous. " (Dr. J. D. White, 1849, _Dental News Letter_. )

"A tin plug will answer a very good purpose in medium and large cavitiesfor six years. Much imposition has been practiced with it, and it is notmade as malleable as it should and can be. An inferior article ismanufactured which possesses brilliancy and resembles silver. This isoften passed off for silver foil. No harm comes from this deceptionexcept the loss of the amount paid above the price for tin; but eventhis inferior tin foil is better than silver. " ("The Practical FamilyDentist, " Dewitt C. Warner, New York, 1853. )

"Tin made into leaves is employed as a stopping material; withsufficient experience it can be elaborated into the finest lines andcracks, and against almost the weakest walls, and teeth are sometimeslost with gold that might have been well preserved with tin. I saw aneffective tin stopping in a tooth of Cramer's, the celebrated musicalcomposer, which had been placed there thirty-five years ago by Talma, of Paris. " ("The Odontalgist, " by J. Paterson Clark, London, 1854. )

Refer to what the same author said in 1836. 

"Tin is the best substitute for gold, and can often be used in badlyshaped cavities where gold cannot. " (Prof. Harris, 1854. )

"Tin is better than any mixture of metals for filling teeth. " (ProfessorTomes, London, 1859. )

In 1860 a writer said that "such a change may take place in the mouth asto destroy tin fillings which had been useful for years, and that tinwas not entirely reliable in any case; it must not be used in a toothwhere there is another metal, nor be put in the bottom of a cavity andcovered with gold, for the tin will yield, and when fluids come incontact with the metals, chemical action is induced, and the tin isoxidized. Similar fillings in the same mouth may not save the teethequally well. Filling is predicated on the nature of decay, for only oncorrect diagnosis can a proper filling-material be selected. "

Reviewing the foregoing statement, we believe that a change may takeplace in the mouth which will destroy gold fillings (or thetooth-structure around them) much oftener than those of tin. It is nowevery-day practice to put tin into the same tooth with another metal; ifthe bottom of a cavity is filled with tin properly packed, it will notyield when completed with gold, and if the gold is tight, the oralfluids cannot come in contact with both metals and produce chemicalaction or oxidation; similar fillings of gold in the same mouth do notsave the teeth equally well. Should we expect more of tin in thisrespect, or discard it because it is not always better than gold?

In Article V of the "New Departure Creed, " Dr. Flagg says, "Skillful andscrupulous dentists fill with tin covered with gold, thereby preventingdecay, pulpitis, death of the pulp, and abscess, and thus save theteeth. "

In 1862 Mr. Hockley, of London, mentions tin for filling, and the sameyear Dr. Zeitman, of Germany, recommended it as a substitute for gold, particularly for poor people. 

"Is tin foil poisonous? If not, why are our brethren so reluctant to useit? Is it nauseous? If not, why not employ it? Will it not preserve theteeth when properly used? Then why not encourage the use of it? Does itsname signify one too common in the eyes of the people, on account of itsdaily use in the tin shops, or do patients murmur when the fee isannounced, because it is nothing but tin? Is it not better than amalgam, although the patient may believe it less costly? Eleven good plugs, twenty-nine years old, in one mouth demonstrates that tin will last aslong as gold in many cases. " (F. A. Brewer, _Dental Cosmos_, 1863. )

"So much tin foil is used for personal and domestic purposes that thefollowing is important: Ordinary tin foil by chemical analysis contained88. 93 per cent. Of lead; embossed foil, 76. 57 per cent. ; tea foil, 88. 66per cent. ; that which was sold for the pure article, 34. 62 per cent. Tinfoil of above kind is made by inclosing an ingot of lead between twoingots of tin, and rolling them out into foil, thus having the tin onthe outside of the lead. " (Dr. J. H. Baldock, _Dental Cosmos_, 1867. )

The author used tin foil for filling the teeth of some of hisfellow-students at the Ohio College of Dental Surgery in 1867. 

"Amalgam should never be used in teeth which can be filled with tin, andmost of them can be. " (Dr. H. M. Brooker, Montreal, 1870. )

"I have used tin extensively, and found it more satisfactory thanamalgam. Dentists ignore tin, because it is easier to use amalgam, lesstrouble. This is not right. If your preceptor has told you that amalgamis as good as tin, and he thinks so, let him write an article in itsdefense. Not one dentist in ten who has come into the profession withinthe last ten years knows how to make a tin filling, and only a few ofthe older ones know how to make a _good_ one. " (Dr. H. S. Chase, _Missouri Dental Journal_, 1870. )

"Among the best operators a more general use of tin would produceadvantageous results, while among those whose operations in gold are notgenerally successful an almost exclusive use of tin would bring about acorresponding quantum of success to themselves and patients, as againstrepeated failures with gold. The same degree of endeavor which lackedsuccess with gold, if applied to tin would produce good results and saveteeth. A golden shower of ducats realized for gold finds enthusiasticadmirers, but a dull gray shower for tin work is not so admirable, eventhough many of the teeth were no better for the gold as gold, nor sowell off in the ultimate as with tin. " (Dr. E. W. Foster, _DentalCosmos_, 1873. )

In 1873 Dr. Royal Varney said, "I am heartily in favor of tin; it is toomuch neglected by our first-class operators. "

"Tin stops the ends of the tubuli and interglobular spaces which areformed in the teeth of excessive vascular organization; if more teethwere filled with tin, and a smaller number with futile attempts withgold, people would be more benefited. " (Dr. Castle, _Dental Cosmos_, 1873. )

"If cavities in teeth out of the mouth are well filled with tin, and putinto ink for three days, no discoloration of the tooth (when split open)can be seen. " (W. E. Driscoll, _Dental Cosmos_, 1874. )

"Tin makes an hermetical filling, and resists the disintegrating actionof the fluids of the mouth. If an operator can preserve teeth forfifteen dollars with tin, which would cost fifty dollars with gold, ought he not to do so? Upon examination of the cavities from whichoxidized plugs have been removed, these oxids will be found to have hada reflex effect upon the dentin; the walls and floors will be discoloredand thoroughly indurated, and to a great degree devoid of sensitiveness, although they were sensitive when filled. Tin is valuable in case ofyouth, nervousness, impatience, high vitality of dentin, lowcalcification, and low pecuniosity. " (Dr. H. Gerhart, _PennsylvaniaJournal of Dental Science_, 1875. )

"Tin Foil for Filling Teeth. " Essay by Dr. H. L. Ambler, read before theOhio State Dental Society. (_Dental Register of the West_, 1875. )

"Some say that if tin is the material the cavity must be filled with, that it must be filled entirely with it, but advanced teachings showdifferently. " (Dr. D. D. Smith, _Dental Cosmos_, October, 1878. )

"Frail teeth can be saved better with tin than with gold. I never saw adevitalized pulp under a tin filling. " (Dr. Dixon, _Dental Cosmos_, May, 1880. )

"Tin may be used as a base for proximate fillings in bicuspids ormolars, in third molars, in children's permanent molars, in thetemporary teeth, and in any cavity where the filling is notconspicuous. " (Dr. A. W. Harlan, _Independent Practitioner_, 1884. )

"Tin in blocks, mats, and tapes is used like non-cohesive gold foil, butabsence of cohesion prevents the pieces from keeping their place as wellas the gold. " ("American System of Dentistry, " 1887. )

This is virtually saying that there is cohesion of non-cohesive gold, and that for this reason it keeps its place better than tin. It hasalways been supposed that there was no cohesion of layers ofnon-cohesive gold, and as the tin is used on the non-cohesive plan, therefore one keeps its place as well as the other. We claim thatgenerally in starting a filling, tin will keep its place better thancohesive or non-cohesive gold, because it combines some of thecohesiveness of the former with the adaptability of the latter. 

"Tin will save teeth in many cases as well or better than gold. Put amat of tin at the cervical wall of proximate cavities in molars andbicuspids, and it makes a good filling which has a therapeutic effect ontooth-structure that prevents the recurrence of caries, probably becausethe infiltration of tin oxid into the tubuli is destructive to animallife. Where the filling is not exposed to mechanical force, there is nomaterial under heavens which will preserve the teeth better. " (Dr. Beach, _Dental Cosmos_, 1889. )

"I extracted a tooth in which I found a cavity of decay which hadextended toward a tin filling, but stopped before reaching it; onexamining the tooth-structure between the new cavity and the tinfilling, it was found to be very hard, indicating apparently that therehad been some action produced by the presence of the tin. " (Dr. G. White, _Dental Cosmos_, 1889. )

"Pure tin in form of foil is used as a filling and also in connectionwith non-cohesive gold. " (Mitchell's "Dental Chemistry, " 1890. )

"Tin ranks next to gold as a filling-material. " (Essig's "DentalMetallurgy, " 1893. )

"Tin is good for children's teeth, when gold or amalgam is notindicated. It can be used in cavities which are so sensitive to thermalchanges as to render the use of gold or amalgam unwise, but it can onlybe used in cavities with continuous walls, and should be introduced inthe form of cylinders or ropes, with wedge-shaped pluggers having sharpdeep serrations, thus depending upon the wedging or interdigitatingprocess to hold the filling in the cavity. " ("Operative Technics, " Prof. T. E. Weeks, 1895. )

"Tin for filling teeth has been almost superseded by amalgam, althoughamong the older practitioners (those who understand how to manipulateit) tin is considered one of the best, if not the very best metal knownfor preserving the teeth from caries. In consequence of its lack of thecohesive property, it is introduced and retained in a cavity upon thewedging principle, the last piece serving as a keystone or anchor to thewhole filling. Each piece should fill a portion of the cavity from thebottom to the top, with sufficient tin protruding from the cavity toserve for thorough condensation of the surface, and the last pieceinserted should have a retaining cavity to hold it firmly in place. Thefoil is prepared by folding a whole or half-sheet and twisting it into arope, which is then cut into suitable lengths for the cavity to befilled. " (Frank Abbott, "Dental Pathology and Practice, " 1896. )

"Forty-three years ago, for a young lady fourteen years of age, Ifilled with non-cohesive gold all the teeth worth filling with thismetal; the rest I filled with tin. Three years after that there was nota perfect gold filling among the whole number, and yet the tin fillingswere just as good as when made. The explanation as to why the tinfillings lasted so much longer than the gold ones was, that there musthave been something in the tin that had an affinity for the teeth andthe elements that formed the dentin, by which some compound was formed, or else it must have been in the adaptation. " (Dr. H. Gerhart, _DentalCosmos_, January, 1897. )

CHAPTER IV. 

At the World's Columbian Dental Congress, held in Chicago, August, 1893, the author presented an essay on "Tin Foil for Filling Teeth. "

During the discussion of the subject, the following opinions wereelicited:

Dr. E. T. Darby: "I have always said that tin was one of the bestfilling-materials we have, and believe more teeth could be saved with itthan with gold. I have restored a whole crown with tin, in order to showits cohesive properties; the essayist has paid a very high and worthytribute to tin. "

Dr. R. R. Freeman: "I have used tin foil for twenty-five years, and knowthat it has therapeutic properties, and is one of the bestfilling-materials, not excepting gold. "

Madam Tiburtius-Hirschfield: "I heartily indorse the use of tin, andhave tested its cohesive properties by building up crowns. "

Dr. A. H. Brockway: "I am a strong believer in the use of tin, onaccount of its adaptability, and the facility with which saving fillingscan be made with it. "

Dr. Gordon White: "After having used tin for nine years, I claim thatit is the best filling-material that has been given to our profession. "

Dr. C. S. Stockton: "Tin is one of the best materials for saving teeth, and we should use it more than we do. "

Dr. James Truman: "I use tin strictly upon the cohesive principle, andwould place it in all teeth except the anterior ones, but would nothesitate to fill these when of a chalky character. "

Dr. Corydon Palmer: "For fifty-four years I have been a firm advocate ofthe use of tin, and I have a filling in one of my teeth which is fortyyears old. "

Dr. William Jarvie: "I rarely fill a cavity with gold for children undertwelve years of age that I want to keep permanently, but use tin, and infive or ten years, more or less, it wears out. Still, it can easily berenewed, or if all the tin is removed we find the dentin hard and firm. The dentist is not always doing the best for his patients if he does notpractice in this way. "

Dr. C. E. Francis: "I have proved positively that tin foil in goodcondition is cohesive, and my views have been corroborated by dentistsand chemists. "

Dr. James E. Garretson: "Tin foil is cohesive, and can be used the sameas gold foil, and to an extent answers the same purpose. "

Dr. C. R. Butler: "Tin is cohesive and makes a first-class savingfilling. "

Dr. W. C. Barrett: "Tin is as cohesive as gold, and if everything wasblotted out of existence with which teeth could be filled, except tin, more teeth would be saved. "

Dr. L. D. Shepard: "Tin possesses some antiseptic properties for thepreservation of teeth that gold does not. "

Dr. W. D. Miller: "I use tin foil in cylinders, strips, and ropes, onthe non-cohesive plan, but admit that it possesses a slight degree ofcohesiveness, and when necessary can be built up like cohesive gold byusing deeply serrated pluggers. "

Dr. Benjamin Lord says, "It is said that we know the world, or learn theworld, by comparison. If we compare tin foil with gold foil, we findthat the tin, being softer, works more kindly, and can be more readilyand with more certainty adapted to the walls, the inequalities, and thecorners of the cavities. 

"We find also that tin welds--mechanically, of course--more surely thansoft gold, owing to its greater softness; the folds can be interlaced orforced into each other, and united with more certainty, and with somuch security that, after the packing and condensing are finished, themass may be cut like molten metal. 

"I contend moreover that for contouring the filling or restoring thenatural shape of the teeth, where there are three walls remaining to thecavity, tin is fully equal to gold, and in some respects even superior;as tin can be secured, where there is very little to hold or retain thefilling, better than gold, owing to the ease and greater certainty ofits adaptation to the retaining points or edges of the cavity. 

"It will be said, however, that tin fillings will wear away. Thesurfaces that are exposed to mastication undoubtedly will wear in time;but the filling does not become leaky if it has been properly packed andcondensed, nor will the margins of the cavity be attacked by furtherdecay on that account. 

"Altogether, I believe that we can make more perfect fillings with tinthan we can with gold, taking all classes of cavities; but it must notbe understood that it is proposed that tin should ever take the place ofgold where the circumstances and conditions indicate that the lattershould be used. Of course, the virtue is not in the gold or the tin, butin the mechanical perfection of the operation, and tin having moreplasticity than gold, that perfection can be secured with more ease andcertainty. 

"If we compare tin with amalgam, we must certainly decide in favor ofthe former and give it preference; as if it is packed and condensed asperfectly as may be, we know just what such fillings will do every time. We know that there will be no changes or leakage of the fillings at themargins; whereas, with amalgam, the rule is shrinkage of the mass, andconsequently the admission of moisture around the filling, the resultbeing further decay. It is not contended that this is always the resultwith amalgam, but it is the general rule; yet we must use amalgam, asthere are not a few cases where it is the best that we can do; but it isto be hoped, and I think it may be said, that as manipulative skilladvances, amalgam will be less and less used. For so-called temporarywork, very often I prefer tin to gutta-percha, as it makes a much morereliable edge and lasts longer, even when placed and packed withoutgreat care. "--_N. Y. Odon. Society Proceedings_, page 51, 1894. 

One of the main reasons which induced the writer to begin the use of tinfoil (_Stannum Foliatum_) for filling teeth, in 1867, was the fact thatamalgam filling failures were being presented daily. Believing that tincould do no worse, but probably would do better, we banished amalgamfrom the office for the succeeding seven years, using in the place ofit tin, oxychlorid, and gutta-percha. Since that time we have seen nogood reason for abandoning the use of tin, as time has proved it worthyof great confidence. There is no better dental litmus to distinguish theconservative from the progressive dentist. 

If we take a retrospective view and consider what tin foil was thirtyyears ago, we do not wonder that so many operators failed to make tight, good-wearing fillings. As it came from the manufacturer it looked fairlybright, but after being exposed to the air for a short time it assumed alight brassy color, and lost what small amount of integrity itoriginally possessed. This tin was not properly refined before beating, or something was put on the foil while beating, so that it did not havethe clean, bright surface and cohesive quality which our best foil nowhas. No. 4 was commonly used, but it would cut and crumble in the mostprovoking manner. Fillings were made by using mats, cylinders, tapes, and ropes, with hand-pressure, on the plan for manipulating non-cohesivegold foil, but it was difficult to insert a respectable approximalfilling. 

From the best information obtainable, the writer believes that MarcusBull (the predecessor of Abbey) was the first to manufacture and selltin foil in the United States, as he began the manufacture of gold foilat Hartford in 1812. 

Several years ago a radical change came about in the preparation of tinfoil, for which the manufacturer should have his share of the credit, even if the dentist did ask for something better, for the qualitydepends largely upon the kind and condition of the tin used and on themethod of manufacture. 

For making tin foil for filling teeth, the purest Banca tin that can beobtained is used. The tin is melted in a crucible under a cover ofpowdered charcoal. It is then cast into a bar and rolled to the desiredthickness, so that if No. 6 foil is to be made, a piece one and one-half(1-1/2) inches square would weigh nine grains. This ribbon is then cutinto lengths of about four feet, and spread on a smooth board slanted, so that the end rests in a vat of clean water. 

Then apply to the exposed surface of the ribbon diluted muriatic acid, and immediately wash with a strong solution of ammonia. Turn the ribbonand treat the other side in the same way. It is then washed and rubbeddry. The object of using the acid is to remove stains and whiten thetin, and the ammonia is used to neutralize the effect of the acid. 

The strips are then cut into pieces one and a half inch square, filledinto a cutch and beaten to about three inches square. It is then removedfrom the cutch and filled into a mold, and further beaten to the desiredsize. When the ragged edges are trimmed off, the foil is ready forbooking. 

It takes skill and experience to beat tin foil, for it is not nearly asmalleable as gold; up to No. 20 it is usually beaten, but higher numbersare prepared by rolling. In each case the process is similar to thatemployed in preparing gold foil. The number on the book is supposed toindicate the weight or thickness of the leaf. On the lower numbers thepaper of the book leaves its impression. 

On weighing sheets of tin foil from different manufacturers a remarkablediscrepancy was found between the number on the book and the number ofgrains in a sheet, viz: Nos. 3, 4, 5, weighed 7 gr. Each; No. 6, 9 gr. ;No. 8, from 9 to 18 gr. ; No. 10, from 14 to 15 gr. ; No. 20, 18 gr. Insome instances the sheets in the same book varied three grains. Wesubmit that it would be largely to the advantage of both manufacturerand dentist to have the number and the grains correspond. No dentistwishes to purchase No. 8 and find that he has No. 18; no one could sellgold foil under like circumstances. Of the different makes tested, White's came the nearest to being correct. The extra tough foil whichcan now be obtained is chemically pure, and with it we can begin at thebase of any cavity, and with mallet or hand force produce a fillingwhich will be one compact mass, so that it can be cut and filed; yet infinishing, it will not bear so severe treatment as cohesive gold. Alwayshandle tin foil with clean pliers, never with the fingers; and prepareonly what is needed for each case, keeping the remainder in the bookplaced in the envelope in which it is sold, otherwise extraneous mattercollects upon it, and it will oxidize _slightly_ when exposed to the airfor a _great_ length of time. 

Before using tin foil, a few prefer to thoroughly crumple it in thehands or napkin, under the impression that they thus make it morepliable and easier to manipulate. 

A piece of blue litmus paper moistened and moved over a sheet of tinfoil will occasionally give an acid reaction, probably owing to the acidwith which it is cleaned before beating not having been thoroughlyremoved. Foil held under the surface of distilled water and boiled forfive minutes, then left until the water is cold, removed and dried, shows it has been annealed, which makes it work easily, but not as harda filling can be made from it as before boiling. 

In selecting and using this material for filling, we are able fully toprotect the cavity; and if we understand the material, and how tomanipulate it, we will surely succeed. This statement demands seriousattention, and appeals to every one who is anxious to practice for thebest interests of his patients; then let us make a thorough study of themerits of the method and material. 

Until recently, the term cohesion had but one special meaning todentists, and that as applied to gold for filling teeth; beingunderstood as the property by which layers of this metal could be unitedwithout force so as to be inseparable. The writer claims that good tinfoil in proper condition is cohesive when force is applied, and can beused for filling teeth in the same manner in which cohesive gold foil isused. This claim has been confirmed by several dentists, as noted inanother part of this volume. 

Cohesion is the power to resist separation, and it acts at insensibledistances. The integral particles of a body are held together bycohesion, the constituent parts are united by affinity. 

The attraction between atoms of pure tin represents cohesion. Marble iscomposed of lime and carbonic acid, which are united and held togetherby affinity. 

The condition which obtains in the tin may be called cohesion, adhesion, welding, or interdigitation, but the fact remains that layers of tinfoil can be driven together into a solid mass, making a tight fillingwith less malleting than is required for gold; if it is overmalleted, the receiving surface is injured. 

On account of its pliability it is easily adapted to the walls andmargins, and a perfect fit is made, thus preventing capillary action andpreventing further caries. Of all the metals used for filling it is thebest tooth-preserver and the most compatible with tooth-substance, andthe facility with which a saving filling can be made largely commendsit. 

Tin has great possibilities, and has already gained a high position as afilling-material. Upon the knowledge we possess of the possibilities andlimitations of tin as a filling-material, and our ability to apply thatknowledge, will largely depend our success in preserving teeth. 

It is a good material for filling many cavities in the temporary teeth, and children will bear having it used, because it can be placed quickly, and but little force is required to condense one or two layers of No. 10foil. The dentin in young teeth has a large proportion of organicmaterial, for which reason, if caries takes place, many believe it ishastened by thermal changes. Gold fillings in such teeth might preventcomplete calcification, on account of the gold being so good aconductor; but if tin is used, there is much more probability ofcalcification taking place, because of its low conductivity and itstherapeutic influence. It does not change its shape after being packedinto a cavity. Under tin, teeth are calcified and saved by the depositof lime-salts from the contents of the dentinal tubuli. This is termedprogressive calcification. 

Like other organs of the human body, the teeth are more or less subjectto constitutional change. The condition in which we find tooth-structurewhich needs repairing or restoring should be a sure indicator to us inchoosing a filling-material. Up to the age of fourteen, and sometimeslater, we find many teeth which are quite chalky. In some mouths also, at this period, the fluids are in such a condition that oxychlorid andoxyphosphate do not last long; for some reason amalgam soon fails, whilegutta-percha is quickly worn out on an occlusal surface. In all suchcases we recommend tin, even in the anterior teeth, for as the patientadvances in years the tooth-structure usually becomes more dense, sothat, if desirable, the fillings can be removed, and good savingoperations can be made with gold. By treating cases in this manner verylittle, if any, tooth-structure is lost. 

The teeth of the inhabitants of Mexico and Guatemala are characteristicof their nervous and nervo-lymphatic temperaments; children ten years ofage often have twenty-eight permanent teeth, and they are generally softor chalky, but our dentists there report good success in saving themwith tin. 

In filling this class of teeth, we should be very careful not to useforce enough to injure the cavity-margin, for if this occurs, a leakyfilling will probably be the result. Still, we have seen some caseswhere _slight_ imperfections at the margin, which occurred at the timeof the filling or afterward, did no harm, because the deposit of tinoxid filled up the ends of the tubuli, thus preventing caries. Webelieve that this bar to the progress of caries is set up morefrequently when tin is used than with any other metal under likeconditions. 

CHAPTER V. 

In some mouths tin does not discolor, but retains a clean, unpolishedtin color, yet when there is a sesquioxid of the metal formed, fillingspresent a grayish appearance. In the same mouth some fillings will bediscolored, while others are not. As a general rule, proximal fillingsare most liable to show discoloration. Perhaps one reason is that onocclusal and buccal surfaces they are subject to more friction frommastication, movements of the cheeks, and the use of the brush. 

We have seen a large number of fillings which were not blackened, yetwere saving the teeth perfectly, thus proving to a certainty thatblackening of tin in the tooth-cavity is not absolutely essential inorder to obtain its salvatory effects as a filling-material. 

Where there is considerable decomposition of food which producessulfuretted hydrogen, the sulfid of tin may be formed on and around thefillings; it is of a yellowish or brownish color, and as an antisepticis in such cases desirable. To offset the discoloration, we find thatthe sulfid is insoluble, and fills the ends of the tubuli, thus lendingits aid in preventing further caries. A sulfid is a combination ofsulfur with a metal or other body. A tin solution acted on bysulfuretted hydrogen (H_{2}S) produces a dark-brown precipitate (SnS), stannous salt, which is soluble in ammonium sulfid (NH_{4})_{2}S_{2};this being precipitated, gives (SnS_{2}) stannic salt, which is yellow. Brown precipitates are formed by both hydrogen sulfid and ammoniumsulfid, in stannous solutions. Yellow precipitates are formed byhydrogen sulfid and ammonium sulfid in stannic solutions. The yellowshade is very seldom seen on tin fillings; the dark brown is morecommon. 

An oxid is a combination of oxygen with a metal or base destitute of anacid. In oxidation the oxygen that enters into combination is notsufficient to form an acid. The protoxid of tin (SnO) is black, and canbe obtained from chlorid of tin, or by _long_ exposure of tin to theatmosphere. The oxygen in the saliva helps to blacken the tin, and themetallic oxid penetrates the dentin more or less, acting as aprotection, because it is insoluble. Oxygen is the only element whichforms compounds with all others, and is the type of electro-negativebodies; it combines with all metals, therefore with tin, and in manycases only the metal is discolored, and not the tooth. Steam boilers aremade tight by oxidation. 

Where there is complete oxidation, the tooth is blackened to but a veryslight depth, and the oxid fills the ends of the tubuli, thus affordingan additional barrier to the entrance of caries. The filling itself willprevent caries, but oxidation acts as an assistant. 

"In the mouth, a suboxid is more likely to be formed than a protoxid, but both are black; sulfur and oxygen are capable of acting on tin underfavorable circumstances, such as warmth, moisture, full contact, condensation of elements, and their nascent conditions; the first threeare always present in the mouth. The protosulfuret of tin is black. "(Dr. George Watt. ) Others give the color as bluish-gray, nearly black. 

Experiments show that slight galvanic currents exist between fillings ofdissimilar metals in the mouth, and practical experience demonstratesthat these currents occasionally produce serious results. 

Direct galvanic currents do not decompose normal teeth by trueelectrolysis, but acids resulting from decomposition of food and fluidsreact upon the lime constituents of the teeth and promote secondarycaries. 

When two metals are so situated in the mouth that the mucous membraneforms a connecting conductor and the fluids are capable of acting onone metal, galvanic action is established sufficient to decompose any ofthe binary compounds contained in these fluids; the liberated nitrogenand hydrogen form ammonia, which being exposed to the action of oxygenis decomposed and nitric oxid formed, resulting in nitric acid. We alsohave in the mouth air, moisture, and decomposing nitrogenous food toassist in the production of nitric acid. 

"Galvanic action is more likely to develop hydrochloric acid, for thechlorids of sodium and potassium are present in the normal saliva andmucus, and when decomposed their chlorin unites with the hydrogenderived from the water of the saliva. " (Dr. George Watt. )

The fact should also be noted that both nitric and hydrochloric acidsare administered as medicine, and often assist in producing decay. 

When there is a battery formed in a mouth containing tin fillings andgold fillings, and the fluids of the mouth are the exciting media, tinwill be the positive element and gold the negative element; thus whenthey form the voltaic pair, the tin becomes coated or oxidized and thecurrent practically ceases. 

There is more or less therapeutical and chemical action in cavitiesfilled with tin, and its compatibility and prophylactic behavior as afilling-material depends partly upon the chemical action which occurs. 

Some dentists fill sensitive cavities with tin, in order to securegentle galvanic action, which they believe to be therapeutic, solidifying the tooth-structure. 

"Tin possesses antiseptic properties which do not pertain to gold forarresting decay in frail teeth; it not only arrests caries mechanically, but in chalky (imperfect) structure acts as an antacid element inarresting the galvanic current set up between the tooth-structure andfilling-material. " (Dr. S. B. Palmer. ) If the metal is acted on, thetooth is comparatively safe; if the reverse, it is more or lessdestroyed. The galvanic taste can be produced by placing a piece ofsilver on the tongue and a steel pen or piece of zinc under it; thenbring the edges of the two pieces together for a short time, rinse thesaliva around in the mouth, and the peculiar flavor will be detected. 

"In 1820 attention was called to the injurious effects of the galvaniccurrent on the teeth, and dentists were advised never to use tin andamalgam in the same mouth. 

"A constant galvanic action is kept up in the mouth when more than onekind of metal is used in filling teeth, and galvanism is often thecause of extensive injury to the teeth. The most remarkable case I eversaw was that of a lady for whom I filled several teeth with tin. After atime decay took place around some of the fillings. I removed them andbegan to refill, but there was so much pain I could not proceed. I foundthat by holding a steel plugger an inch from the tooth I could give hera violent galvanic shock. I observed that the exhalation of the breathincreased the evolution of galvanism. " (Dr. L. Mackall, _AmericanJournal of Dental Science_, 1839. )

"When a faulty tooth in the upper jaw had been stopped from its sidewith tin, the interstice between it and the adjoining tooth being quiteinconsiderable, while the upper surface of a tooth not immediatelybeneath it in the lower jaw was stopped with the same metal, I haveknown a galvanic shock regularly communicated from one tooth to theother when by the movement of jaws or cheeks they were brought neartogether. " (Dr. E. Parmly, _American Journal of Dental Science_, 1839. )

"An interesting debate here sprung up on the action where two metals areused in one filling, such as gold and tin, the saliva acting as amedium, and where the baser metal is oxidized by exhalents and byimbibition through the bony tooth-structure. " (Pennsylvania Society ofDental Surgeons, 1848. )

"A patient came to me and complained of pain in the teeth. Uponexamination I found an amalgam filling next to one of tin. With a file Imade a V-shaped separation, when they experienced immediate relief frompain. " (Dr. Nevill, _American Journal of Dental Science_, 1867. )

In regard to the decay of teeth being dependent on galvanic actionpresent in the mouth, Dr. Chase, in 1880, claimed that a tooth filledwith gold would necessarily become carious again at the margin of thecavity, wherever the acid secretions constantly bathe the filling andtooth-substance. A tooth filled with amalgam succumbs to thiselectro-chemical process less rapidly, while one filled with tin stilllonger escapes destruction. The comparative rapidity with which teethfilled with gold, amalgam, or tin, are destroyed is expressed by thenumbers 100, 67, 50. He prepared pieces of ivory of equal shape andsize, bored a hole in each, and filled them. After they had been exposedto the action of an acid for one week, they had decreased inweight, --viz, piece filled with gold, 0. 06; amalgam, 0. 04; tin, 0. 03. 

"With tin and gold, some have the superstition that the electricityattendant upon such a filling will in some way be injurious to thetooth; it matters not which is on the outside, when rolled and used asnon-cohesive cylinders each appears. We say that neither experimentally, theoretically, nor practically can any good or bad result be expectedfrom the electrical action of a tin-gold filling on tooth-bone, andneither will the pulp be disturbed. " (Dr. W. D. Miller, _IndependentPractitioner_, August, 1884. )

"When the bottom of a cavity is filled with tin which is tightly(completely) covered with gold, there is _practically_ no galvanicaction and there is no current generated by contact of tin andgold, --_i. E. _, no current leaves the filling to affect the dentin. Thatportion of tin which forms the base is more positive than a full tinfilling would be. The effect is to cause the surface exposed to dentinto oxidize more than tin would do alone; in that there is a benefit. Invery porous dentin there is enough moisture to oxidize the tin, byreason of the current set up by the gold. " (Dr. S. B. Palmer. )

Electricity generated by heat is called thermo-electricity. If a cavitywith continuous walls is half filled with tin and completed with gold, or half filled with silver and completed with gold, and the junctions ofthe metal are at 20-1/2° C. And 19-1/2° C. , if the electrical actionbetween the tin and gold be 1. 1, the action between the silver and goldwill be 1. 8, thus showing the action in silver and gold to be nearlytwo-thirds more than in the tin and gold, a deduction which favors thetin and gold. 

Rubbing two different substances together is a common method ofproducing an electric charge. Is there not more electricity generatedduring mastication on metal fillings than when the jaws are at rest?Friction brings into close contact numerous particles of two bodies, andperhaps the electrical action going on more or less all the time throughgold fillings (especially when other metals are in the mouth) accountsfor a powdered condition of the dentin which is sometimes found undercohesive gold fillings, but not under tin. 

CHAPTER VI. 

White caries, the most formidable variety known, may be produced bynitric acid, and in these cases all the components of the tooth areacted upon and disintegrated as far as the action extends. In proximalcavities attacked by this kind of caries, separate freely on the lingualside, and fill with tin. When such fillings have been removed the dentinhas been found somewhat discolored and greatly solidified as compared toits former condition; this solidification or calcification is morefrequent under tin than gold, which is partly due to the tin as a poorconductor of heat. Nature will not restore the lost part, but will dothe next best thing--solidify the dentin. In some cases, under tin, thepulp gradually recedes, and the pulp-cavity is obliterated by secondarydentin. In other cases the pulps had partly calcified under tin. It hasbeen known for years that tin would be tolerated in large cavities verynear the pulp without causing any trouble, and one reason for this isits low conducting power. Attention is called to the fact that gold isnearly four times as good a conductor of heat as tin, and more than sixtimes as good a conductor of electricity. Where tin fillings aresubject to a large amount of attrition, they wear away sooner or later, but this is not such a great detriment, for they can easily be repairedor replaced, and owing to the concave form produced by wear the patientis liable to know when a large amount has been worn away. That portionagainst the wall of the cavity is the last removed by wear, so thatfurther caries is prevented so long as there is any reasonable amount oftin left. If at this time the tooth has become sufficiently solidified, proper anchorage can be cut in the tin or tooth, one or both, asjudgment dictates, and the filling completed with gold. A tin filling, confined by four rather frail walls, may condense upon itself, but it isso soft and adaptable that the force which condenses it continuallysecures the readaptation at the margin; thus there will be no leakage orcaries for years. Owing to its softness and pliability, it may be driveninto or onto the tubuli to completely close them from outside moisture, and with a hand burnisher the tin can be made to take such a hold ondry, rough tubuli that a cutting instrument is necessary to remove alltraces of it. 

Tin foil has been found in the market that under a magnifying glassshowed innumerable tiny black specks, which, upon being touched with aninstrument, crumbled away, leaving a hole through the foil. More thanlikely, some of the failures can be attributed to the use of such foil. Good tough foil, well condensed by hand or mallet force, stays againstthe walls of a cavity and makes a tight filling, and ought to be calledas near perfect as any filling, because it preserves the tooth, andgives a surface which will wear from five to twenty years, dependingupon the size and location of the cavity and tooth-structure. Buccalcavities in the first permanent molars, and lingual cavities in thesuperior incisors, filled for children from six to eight years of age, are still in good condition after a period of twenty years. Perhaps thelimit is reached in the following cases, all in the mouths of_dentists_: One filling forty years old; one forty-two; four on theocclusal surface, fifty; in the latter case gold had been used in othercavities and had failed several times. Lingual cavities in molars andbicuspids can be perfectly preserved with tin. Tapes of No. 10 foil, from one to three thicknesses, can be welded together and will cohere aswell or better than semi-cohesive gold foil, and it can be manipulatedmore rapidly; therefore, if desirable, any degree of contour can beproduced, but the contour will not have the hardness or strength ofgold, so in many cases it would not be practicable to make extensivecontours with tin, owing to its physical characteristics. 

No. 10 will answer for all cases, and it is not as liable to be torn orcut by the plugger as a lower number, but one need not be restricted toit, as good fillings can be made with Nos. 4, 6, or 8. More teeth can besaved with tin than with any other metal or metals, and the averagedentist will do better with tin than with gold. It is invaluable whenthe patient is limited for time or means, and also for filling the firstpermanent molars, where we so often find poor calcification oftooth-structure. In cases of orthodontia, where caries has attacked alarge number of teeth, it is well to fill with tin, and await furtherdevelopments as to irregularity and caries. 

If cavities are of a good general retaining form, that will besufficient to hold the filling in place; but if not, then cut slightopposing angles, grooves, or pits. Cavities are generally prepared thesame as for gold, except where there is a great deal of force broughtupon the filling; then the grooves or pits may be a little larger;still, many cavities can be well filled with less excavating thanrequired for gold, and proximal cavities in bicuspids and molars, wherethere is sufficient space, can be filled without removing the occlusalsurface, and here especially should the cavities be cut square into theteeth, so as not to leave a feather edge of tin when the filling isfinished, as that would invite further caries and prove an obstructionto cleansing the filling with floss. 

In proximal cavities involving the occlusal surface, cut the cervicalportion down to a strong square base, with a slight pit, undercut, orangle, at the buccal and lingual corners; where there is sufficientmaterial, a slight groove across the base, far enough from the margin sothat it will not be broken out, can be made in place of the pit, undercut, or angle; then cut a groove in the buccal and lingual side(one or both, according to the amount of material there is to workupon), extending from the base to the occlusal surface; in most of thesecases the occlusal grooves or pits would have to be excavated on accountof caries; thus there would be additional opportunity for anchorage. Inplace of the grooves the cavity may be of the dovetail form. In nearlyall proximal cavities in bicuspids and molars, some form of metalshield, or matrix, is of great advantage, as they prevent the tin fromcrushing or sliding out. By driving the tin firmly against the metal, awell-condensed surface is secured; and as the metal yields a little, wecan with a bevel or thin plugger force the tin slightly between themetal and the margin of the cavity, thus making sure of a tight filling, with plenty of material to finish well. After removing the metal, condense with thin burnishers and complete the finish the same as forgold. Where no shield or matrix is used, or where it is used and removedbefore completing the filling, it is often desirable to trim thecervical border, for in either case there is more light and room to workwhen only a portion of the cavity has been filled. Tin cuts so mucheasier than gold, it is more readily trimmed down level with allcervical margins. 

Be sure that all margins are made perfect as the work progresses, and ifthe cavity is deep and a wide shield shuts out the light, then use anarrow one, which can be moved toward the occlusal surface from time totime. 

In filling the anterior teeth when the labial wall is gone, and thelingual wall intact or nearly so, use a piece of thin metalthree-quarters of an inch long and wide enough to cover the cavity inthe tooth to be filled, insert it between the teeth, and bend thelingual end over the cavity; the labial end is bent out of the way overthe labial surface of the adjoining tooth, as shown in Fig. 4. When thelabial wall is intact or nearly so, access to the cavity should beobtained from the lingual side, and in this case the bending of theshield would be reversed, as shown in Fig. 5. The shield is notabsolutely essential, but it helps support the tin, and also keeps aseparation. 

[Illustration: FIG. 4. ]

[Illustration: FIG. 5. ]

It is preferable to save the labial wall and line it with (say) fivelayers of No. 4 semi-cohesive gold folded into a mat and extended to theouter edge of the cavity; this gives the tooth a lighter shade, andbicuspids or molars can be filled in the same manner. Cases are onrecord where incisors with translucent labial walls, filled by thismethod, have lasted from twenty-three to thirty-seven years. 

CHAPTER VII. 

For the last ten years the writer has been using tin at the cervicalmargin of proximal cavities in bicuspids and molars, especially in deepcavities (now an accepted practice), and he finds that it preventsfurther caries oftener than any other metal or combination of metals hehas ever seen used. In filling such cavities, adjust the rubber, and usea shield or matrix of such form as to just pass beyond the cervicalmargin; this will generally push the rubber out of the cavity, but if itdoes not, then form a wedge of wood and force between the metal and theadjoining tooth, thus bringing the metal against the cervical margin, and if a small film of rubber should still remain in the cavity, it maybe forced out by using any flat burnisher which will reach it, or it canbe dissolved out with a little chloroform. Fill from one-fourth toone-half of the cavity with tin, and complete the remainder with goldwhen the tooth is of good structure; this gives all the advantages ofgold for an occlusal surface. 

Before beginning with the gold, have the tin solid and square across thecavity, and the rest of the cavity a good retaining form, the same asfor gold filling; then begin with a strip of gold slightly annealed andmallet it into the tin, but do not place too great reliance upon theconnection of the metals to keep the filling in place. 

On the same plan, proximal cavities in the anterior teeth can be filled, and also buccal cavities in molars, especially where they extend to theocclusal surface. The cervical margin should be well covered with tinthoroughly condensed, thus securing perfect adaptation, and a solid basefor the gold with which the filling is to be completed. Time has fullydemonstrated that the cervical margin is most liable to caries, and herethe conservative and preservative qualities of tin make it speciallyapplicable. 

"Electrolysis demonstrates to us that no single metal can be decomposed, but when gold and tin are used in the above manner they are united atthe line of contact by electrolysis. The surface of both metals isexposed to the fluids of the mouth, and the oxid of tin is deposited onthe tin, by reason of the current set up by the gold; thus some atoms oftin are dissolved and firmly attached to the gold, but the tin does notpenetrate the gold to any great extent. " (Dr. S. B. Palmer. )

This connection of the metals assists in holding the filling in place, but it is more likely to break apart than if it was all gold. Afterelectrolysis has taken place at the junction, it requires a cuttinginstrument to completely separate the tin and gold. 

For filling by hand pressure, use instruments with square ends andsides, medium serrations, and of any form or size which will best reachthe cavity. 

For filling with the hand mallet, use instruments with mediumserrations, and a steady medium blow with a four-ounce mallet; in forceof blow we are guided by thickness of tin, size of plugger, and depth ofserrations, strength of cavity-walls and margins, the same as in usinggold. The majority of medium serrated hand mallet pluggers will workwell on No. 10 tin of one, two, or three thicknesses. If the tin showsany tendency to slide, use a more deeply serrated plugger. Theelectro-magnetic, and mechanical (engine) mallet do not seem to work tinas well as the hand mallet or hand force, as the tendency of suchnumerous and rapid blows is to chop up the tin and prevent the making ofa solid mass, and also injure the receiving surface of the filling. Inusing any kind of force, _always_ aim to carry the material to placebefore delivering the pressure, or blow. 

In order to obtain the best results, there must be absolute dryness, andcare must be exercised, not thinking that because it is _tin_ it will beall right. Skill is required to make good tin fillings, as well as whenmaking good gold fillings. Always use tapes narrower than the orifice ofthe cavity; they are preferable to rolls or ropes. After a few trials itis thought that every one will have the same opinion. A roll or ropenecessarily contains a large number of spaces, wrinkles, orirregularities, which must be obliterated by using force in order toproduce a solid filling; thus more force is employed, and more timeoccupied in condensing a rope, than a flat tape; the individual blow inone case may not be heavier than in the other, but the rope has to bestruck more blows. The idea that a rope could be fed into a cavity witha plugger faster and easier than a tape has long ago been disproved. Many of the old-fashioned non-cohesive gold foil operators used flattapes, as did also Dr. Varney, one of the kings of modern cohesive goldoperators. 

The tape is made by folding any portion of a sheet of foil upon itselfuntil a certain width and thickness is obtained. This tape is verydesirable in small or proximal cavities where a roll or rope would catchon the margin and partially conceal the view. 

In the form of a tape, perhaps more foil can be put in a cavity, andthere may be more uniform density than when ropes are used. Tapes canalso be made by folding part of a sheet of foil over a thin, narrowstrip of metal. Fold the tin into tapes of different lengths, widths, and thicknesses, according to the size of the cavity; then fold the endof the tape once or twice upon itself, place it at the base of anyproximal cavity, and begin to condense with a foot plugger of suitablesize, and if there is a pit, groove, or undercut which it does notreach, then use an additional plugger of some other form to carry thetin to place; fold the tape back and forth across the cavity, proceedingas for cohesive gold. In small proximal cavities a very narrow tape ofNo. 10, one thickness, can be used successfully. For cavities in theocclusal surface, use a tape as just described, generally beginning atthe bottom or distal side, but the filling can be started at anyconvenient place, and with more ease than when using cohesive gold. Inany case if the tin has a tendency to move when starting a filling, "Ambler's left-hand assistant" is used, by slipping the ring over thesecond finger of the left hand, letting the point rest on the tin. Thisinstrument is especially valuable in starting cohesive gold (see Fig. 6). This is the easiest, quickest, and best manner of making a goodfilling, relying upon the welding or cohesive properties of the tin. 

Many operators have not tried to unite the tin and make a solid mass;they seem to think that it cannot be accomplished, but with properpluggers and manipulation it can be done successfully. 

[Illustration: FIG. 6. ]

For large occlusal or proximal cavities, the tapes may be folded intomats, or rolled into cylinders, and used on the plan of wedging orinterdigitation, and good fillings can be produced by this method, butthe advantage of cohesion is not obtained, and more force is requiredfor condensing. They are, therefore, not so desirable as tapes, especially for frail teeth. When using mats or cylinders, the generalform of the cavity must be depended upon to hold the filling in place. To make the most pliable cylinders, cut a strip of any desired widthfrom a sheet of foil and roll it on a triangular broach, cutting it offat proper times, to make the cylinders of different sizes. 

A cylinder roller, designed by the author, is much superior to a broach. (See Fig. 7. ) When the cavity is full, go over the tin with a mallet orhand burnisher, being careful not to injure the cavity-margin. Cut downocclusal fillings with burs or carborundum wheels, and proximal fillingswith sharp instruments, emery strips or disks. After partiallyfinishing, give the filling another condensing with the burnisher, thena final trimming and moderate burnishing; by this method a hard, smoothsurface is obtained. 

Fillings on occlusal surfaces can be faced with No. 20 or 30 tin, andburnished or condensed, by using a burnisher in the engine, but do notrely upon the burnisher to make a good filling out of a poor one. 

[Illustration: FIG. 7. ]

By trimming fillings before they get wet, any defects can be remedied bycutting them out; then with a thin tape (one or two layers of No. 10)and serrated plugger proceed with hand or mallet force to repair thesame as with cohesive gold. 

Another method of preparing tin for fillings is to make a flat, roundsand mold; then melt chemically pure tin in a clean ladle and pour itinto the mold; put this form on a lathe, and with a sharp chisel turnoff thick or thin shavings, which will be found very tough and cohesivewhen freshly cut, but they do not retain their cohesive properties forany great length of time, --perhaps ten or twenty days, if kept in atightly corked bottle. After more or less exposure to the air theybecome oxidized and do not work well, but when they are very thin theyare soft, pliable, and cohesive as gold, and any size or form of fillingcan be made with them. 

Among the uses of tin in the teeth, the writer notes the following fromDr. Herbst, of Germany: "After amputating the coronal portion of thepulp, burnish a mat of tin foil into the pulp-cavity, thus creating anabsolutely air-tight covering to the root-canal containing the remainderof the pulp; this is the best material for the purpose. " There has beena great deal said about this method, pro and con, notably the latter. The writer has had no practical experience with it, and it need not beunderstood that he indorses it. 

If a pulp ever does die under tin, perhaps it will not decompose asrapidly as it otherwise would, owing to its being charged withtin-salts. 

The Herbst method of filling consists in introducing and condensing tinin cavities by means of smooth, highly tempered steel engine or handburnishers. In the engine set of instruments there is one oval endinverted cone-shaped, one pear-shaped, and one bud-shaped. The revolvingburnisher is held firmly against the tin, a few seconds in a place, andmoved around, especially along the margins, not running the engine toofast. Complicated cavities are converted into simple ones by using amatrix, and proximal cavities in bicuspids and molars are entered fromthe occlusal surface. The tin foil is cut into strips, and then madeinto ropes, which are cut into pieces of different lengths; the firstpiece must be large enough so that when it is condensed it will liefirmly in the cavity without being held; thus a piece at a time is addeduntil the cavity is full. The hand set of burnishers has four which arepear-shaped and vary in size, and one which is rather small androof-shaped. In filling and condensing they are rotated in the handone-half or three-quarters of a turn. 

Dr. Herbst claims a better adaptation to the walls of the cavity than byany other method. Proximal cavities in bicuspids and molars can easilybe filled; the tin can be perfectly adapted against thin walls of enamelwithout fracturing them; less annoyance to the patient and less work forthe dentist; can be done in half the time required for other methods. 

Fees should be reasonably large, certainly more than for amalgam, forwe can save many teeth for a longer time than they could have beenpreserved with cohesive gold. Many are not able to pay for gold, butthey want their teeth filled and _saved_, and it is expected that wewill do it properly and with the right kind of material; thus it is ourduty in such cases to use more tin and less amalgam. 

We should always take into consideration the amount of good accomplishedfor the patient, --the salvation of the tooth, --and if we are sure, fromexperience and observation, that the tin filling will last as long as agold one in the same cavity, or longer, then the fee should be as muchas for gold, with the cost of the gold deducted. The amount of the feeought to be based upon the degree of intelligence, learning, and skillrequired; upon the amount of nervous energy expended; upon the draftmade on the dentist's vitality; upon what benefit has been given thepatient; upon the perfection of the result; and, everything else beingequal, upon the time occupied; the value of this last factor beingestimated in proportion to the shortness of it. 

CHAPTER VIII. 

Dr. Robinson's Fibrous and Textile Metallic Filling is a shreddedmetallic alloy, mostly tin, and has the appearance of woven or feltfoil. It is prepared in a machine invented by the doctor especially forthe purpose, and he gives directions for using as follows: "Cut thematerial into strips running with the selvage, and fill as you wouldwith soft foil; use it in all surrounding walls, and finish with amallet burnisher. Where the surface comes to hard wear, weld on goldwith long, sharp serrated pluggers, and finish the same as with goldfillings. The advantage over gold for cervical, buccal, and lingualwalls is the perfect ease with which it is adapted, and it can beburnished so as to be absolutely impervious to moisture. Sharp, coarse-serrated pluggers are particularly desirable when using handpressure. " It comes in one-half-ounce boxes, filled with sheets lessthan two inches square; the thin ones are used for filling, and thethick ones make good linings for vulcanite. 

This material is easy to manipulate, but great care is required incondensing at cavity-margins, so as to make a tight filling, and alsonot injure the margins. It makes as hard a surface as tin foil, and canbe cut, polished, and burnished so that it is smooth and looks well; itcan be used in temporary or chalky teeth, as a small amount of forcecondenses it. By using a matrix proximal cavities can be filled fromone-fourth to one-half full, and the rest filled with gold, relying onthe form of the cavity to hold the gold, regardless of its connectionwith the fibrous material. If the surface is not overmalleted so as tomake it brittle or powdery, a strip of No. 4 cohesive gold, of four orfive thicknesses, may be driven into it with a hand mallet and pluggerof medium serrations; this union is largely mechanical, but ofsufficient tenacity to make manipulation easy, as the material makes asolid foundation to build upon. After exposure to the oral fluids, electrolysis takes place at the junction of the metals. 

In 1884 Dr. Brophy said, "I have used Robinson's material for two years, and find it possesses good qualities, and can be used in deciduousteeth, first permanent molars, and cervical margins with better resultsthan can be obtained with any other material by the majority ofoperators. "

Malleted with deeply serrated pluggers, it will make a filling whichwill not leak. It has saved many teeth from caries at the cervicalmargin where it might have recurred sooner had cohesive gold been used. In the mouth it changes color about the same as tin foil, and a fewfillings did not maintain their integrity, but became crumbly andgranular. 

For conducting properties it ranks about with tin, and fillings can bemade more rapidly than with cohesive gold. We have used ounces of it, but time has proved that everything that can be done with it in fillingteeth can also be accomplished as well and in some cases better with tinfoil. 

In 1878 Dr. N. B. Slayton patented his Felt Foil, which was said to betin cut into hair-like fibers by a machine, then pressed into smallsheets and sold in one-half-ounce books, but it sold only to a verylimited extent. Soon after this Dr. Jere Robinson, Sr. , invented amachine and began the manufacture of a similar article, but he found hewas infringing on the Slayton patent, so he purchased the Slaytonmachine and made satisfactory terms to continue his own manufacture offibrous material. After this little was heard of Slayton's Felt Foil, but Robinson's was considerably used. The two materials look and aremanipulated almost exactly alike. Dr. Robinson has both ofabove-mentioned machines now in his possession. 

Archibald McBride, of Pittsburg, Pa. , in 1838, made a roll of a portionof a sheet of tin, and then used just enough gold to cover it, aimingto keep the gold on the surface, so as to have the filling look like oneof all gold, and not with the idea of deriving any special benefit fromthe effects of wear or preservation as obtained by thus combining thetwo metals. The fee for a gold filling was one dollar; tin, fifty cents. Some operators have advocated using tin and gold (symbol Tg), rolled orfolded together in alternate layers, thus exposing both metals to thefluids of the mouth; claiming that fillings can be made quicker, are notso subject to thermal changes, and can be inserted nearer the pulp thanwhen gold is used. This may be true in comparison with gold, but thesethree claims are entirely met by using tin alone. Others say that thisunion of gold and tin will preserve the teeth as well as a correct goldfilling, making no conditions or restrictions as to tooth-structure orlocation of cavity. They say that it preserves the cervical marginbetter than gold; that it expands _slightly_. 

A description of some different methods of combining and manipulatingtin and gold is subjoined:

(_a_) Two sheets of No. 4 cohesive gold and one of the same number oftin are used; place the tin between the gold, cut off strips, and usewith hand or mallet force the same as cohesive gold; if non-cohesivegold is used, the strips can be folded into mats or rolled intocylinders, and are used on the wedging plan, the same as non-cohesivegold, or the strips can be folded back and forth in the cavity until itis full. 

(_b_) Lay a sheet of non-cohesive gold, No. 3, on a sheet of tin of thesame number, cut off strips, roll into ropes and use as non-cohesivegold. It is easily packed and harder than tin, and has a preservativeaction on the teeth. Line the cavity with chloro-balsam as an insulatoragainst possible currents and moisture; especially should this be donein large cavities or chalky teeth. 

(_c_) A sheet of non-cohesive gold, No. 4, is laid on a sheet of tin ofthe same number, cut into strips and rolled into cylinders, or foldedinto blocks, always in equal portions; then they will unite to theextent of two leaves. These fillings sometimes become a solid mass aboutthe color of amalgam, and last very well, as the metals have becomeunited by electrolysis. An excess of tin will be marked by lines or pitsin the filling, showing where the tin has been disintegrated ordissolved by the chemical action which occurs on the surface exposed tomoisture. 

No doubt, good fillings have been made by the above methods, yet somewere granular, gritty, and were easily removed, while others were quitesmooth and hard; probably in the first instance the proportion of tinand gold was not proper, --that is, not equal; or it was not wellcondensed. Tin being the positive element, it is more easily acted onand disintegrated by electrolysis (chemical action of the fluids). 

When this combination does become hard, it wears longer than tin on anocclusal surface, but we believe that in some cases where it was usedthe teeth could have been saved just as well with either tin or gold, orby filling part of the cavity with tin and the rest with gold. 

If tin foil is laid on 22-carat gold and vulcanized, it becomesthoroughly attached and will take a tin polish; the attraction orinterchange of atoms takes place to this extent. 

This combination of tin and gold can be used at the cervical margin, ora cavity can be lined with it, and the remainder filled with cohesive ornon-cohesive gold. 

"Tin and gold (Tg) folded or rolled together in equal portions possessesa greater number of desirable properties than any other material, for itis easily adapted, has antiseptic action and a lower conductivity thangold. A new filling is harder than tin, softer than gold, but after atime it becomes as hard as amalgam. It oxidizes and thus helps maketight margins, and is very useful at cervical margins; generallydiscolors, but not always, and does not discolor the tooth unless acarious portion has been left, and then only discolors that portion. Inoral fluids it is indestructible if well condensed, otherwise it iscrumbly. There is no change of form, except a _slight_ expansion, whichdoes no harm. A weak electric current is set up between the gold andtin, and tin oxid is formed. The hardening and discoloration both dependupon the separation of the tin by the electrical action and itsdeposition on the surface of the gold. I generally prepare cavities thesame as for non-cohesive gold, but a Tg filling may be held in a moreshallow cavity and with less undercuts than for gold. Hand pressure isadopted, but a mallet may be used advantageously. Lay a sheet of No. 4non-cohesive gold on a sheet of No. 4 tin, then cut into strips andtwist into ropes; keep the tin on the outside, for it does not tear aseasily as gold. Carry the material against the walls and not against thebase, otherwise the filling will be flat or concave; but should thisoccur, then force a wedge-shaped plugger into the center of the filling, and drive the material toward the walls, and then fill the hole orremove all the filling and begin anew. 

"In very deep cavities use a mat of Tg, dampened in carbolic acid anddipped in powdered thymol, as a base; this has an antiseptic action, andalso prevents pressure on or penetration into the pulp. 

"Drs. Abbot, Berlin; Jenkins, Dresden; Sachs, Breslau, have observedtin-gold fillings from fifteen to twenty-five years, and say that forcertain cases it is better than any other material. I use square-pointedpluggers (four-cornered), as part of the packing is done with the sideof the plugger. Tg is useful in partly erupted molars, buccal cavitiesunder the gums, occlusal cavities in temporary teeth, cavities where alldecay cannot be removed. Use Tg with a gold capping in small, deepocclusal cavities, cavities with overhanging walls, occlusal cavitieswith numerous fissures, large, deep occlusal cavities near the pulp, inproximal cavities. 

"Line labial walls of incisors with non-cohesive gold, and fill theremainder with Tg. For repairing gold fillings I use Tg. " (Dr. Miller, Berlin, _Dental Cosmos_, 1890. )

Dr. Jenkins, of Dresden, says, "I use Tg in soft, imperfect teeth, ofwhich there are plenty in Germany, because it has pliability, adaptability, slight susceptibility to thermal changes, makes awater-tight joint, very useful at cervical margins, and can be used witha minimum amount of pressure. When packed dry and with the gold next tothe tooth, discoloration occurs only on the surface; packed wet, thewhole discolors. I do not attribute its success to electrical action. Lay a sheet of No. 4 tin on a sheet of No. 4 non-cohesive gold, fold soas to keep the gold on the outside; use the strip with lateral pressure, doubling it upon itself. "

Dr. A. H. Thompson: "After several years' successful use of tin-gold, Icommend it for approximal cavities, cervical margins, and frail walls. The oxid formed penetrates the enamel and dentin; if a filling wearsdown, cover the surface with gold. "

Dr. Pearson: "I do not like tin and gold in alternate layers. I preferNo. 10 tin foil. "

Dr. James Truman: "I believe that tin-gold has a positive value as afilling-material. "

"I prepare tin-gold by taking a sheet of No. 4 non- or semi-cohesivegold, fold them together (or twist them) so as to have the gold on theoutside, and then fill any cavity with it. Since adopting the abovecombination I have almost abandoned amalgam. This is recommended onaccount of its density, ease of insertion, capacity for fine finish, non-conducting and non-shrinking qualities, and compatibility withtooth-substance. Those who have not used it will be surprised at therapidity with which it can be manipulated. It may be employed in anycavity not exposed to view, also in crown, buccal, and approximalfillings which extend into the occlusal surface, as it offers anastonishing resistance to wear. It can be used anywhere that amalgamcan, and with more certainty of non-leakage, and it has the additionaladvantage that it can be finished at the same sitting. Care is necessaryin manipulating it, so as to avoid chopping. I use hand pressure whenfilling, and the mallet to condense the surface. " (Dr. A. W. Harlan, _Independent Practitioner_, 1884. )

"Pure tin foil is employed in connection with non-cohesive gold infilling proximal cavities in bicuspids and molars; a sheet of gold and asheet of tin are folded together. " (C. J. Essig: "ProstheticDentistry. ")

Dr. Benj. Lord says, "A combination in which I find great interest is inthe use of soft or non-cohesive gold with tin foil. This is no noveltyin practice, but I think that, for the most part, too great a proportionof tin has been used, and hence has arisen the objection that the tindissolved in some mouths. I am satisfied that I myself until recentlyemployed more tin than was well. I now use from one-tenth to one-twelfthas much tin as gold, and no disintegration or dissolving away of thetin ever occurs. I fold the two metals together in the usual way offolding gold to form strips, the tin being placed inside the gold. Theaddition of the tin makes the gold tougher, so that it works more liketin foil. The packing can be done with more ease and certainty; thefilling, with the same effort, will be harder, and the edges or marginsare stronger and more perfect. 

"The two metals should be thoroughly incorporated by manipulation. Then, after a time, there will be more or less of an amalgamation. By usingabout a sixteenth of tin, the color of the gold is so neutralized thatthe filling is far less conspicuous than when it is all gold, and I veryoften use such a proportion of tin in cavities on the labial surfaces ofthe front teeth. 

"If too much tin is employed in such cases, there will be somediscoloration of the surface of the fillings; but in the proportion thatI have named no discoloration occurs, and the surface of the fillingwill be an improvement on gold in color. "

"Dr. Howe. I would like to ask Dr. Lord whether, in referring to theproportions of tin and gold, he means them to be considered by weight?

"Dr. Lord. No, not by weight, but by the width of the strip of tin andthe width of the strip of gold. I get the proportions in that way, thenlay the tin on the gold and fold the gold over and over, which keeps thetin inside the gold. 

"Dr. Howe. Will Dr. Lord tell us whether he refers to the same numbersof gold foil and tin foil; as, for instance, No. 4 gold and No. 4 tin?

"Dr. Lord. I use the No. 5 gold, and tin, I think, of about thesame number, but I always use No. 5 gold, both cohesive andnon-cohesive. "--_New York Odontological Society Proceedings_, 1893, page103. 

"Tin and gold, in the proportions generally used, do not present apleasing color; when finished, it looks but little better than tin, andafter a short time it grows dark, and sometimes black. I use five partsof gold to one of tin, prepared as follows: Lay down one sheet ofAbbey's non-cohesive gold foil, No. 6; upon this place a sheet of No. 4;upon this place a sheet of White's globe tin foil, No. 4; upon thisanother sheet of Abbey's non-cohesive gold, No. 4; upon this a sheet ofNo. 6. Cut into five strips and crimp; the crimped strips are cut intopieces a little longer than the depth of the cavity to be filled; someof the strips are rolled into cylinders, others are left open, becauseeasier to use in starting a filling. The color of this combination isslightly less yellow than pure gold, and hardens just as rapidly as whenthe proportions are one to one, but does not become quite as hard. Thispreparation is non-cohesive, and should be inserted by the wedgeprocess. I use it in the grinding surface of molars and bicuspids, buccal cavities in molars and bicuspids, cervical fissure pits insuperior incisors, proximal cavities in bicuspids and molars. Ifproximal cavities are opened from the occlusal surface, the last portionof the filling should be of cohesive gold to withstand mastication. Insimple cavities I place as many pieces as can be easily introduced, using my pliers as the wedging instrument to make room for the lastpieces, and then condense the whole. If the cavity is too deep for this, I use Fletcher's artificial dentin as a base, because it partly fillsthe cavity and the ends of the cylinders stick to it. After anapproximal cavity is prepared, use a matrix held in place by woodenwedges; the cylinders are about one-eighth of an inch long, andcondensed in two or three layers so as to secure perfect adaptation;hand pressure is principally used, but a few firm strokes with a handmallet are useful. When ready to add the cohesive gold for thegrinding-surface, a few pieces of White's crystal mat gold should firstbe used, because it adheres beautifully; thus a perfect union issecured, but I never risk adding the gold without leaving a littleundercut for it in the tooth. By this method we obtain a beautifulcontour filling in a short time. Fillings should be burnished and thenpolished with a fine strip, or moistened pumice on a linen tape. Wherecohesive gold is used for the entire filling, in many cases theenamel-walls, already thin near the cervical margin, are made thinner bythe unavoidable friction of the polishing strips, but tin and gold is sosoft that a good surface is obtained in a few moments, and this dangeris reduced to a minimum. The surface is as smooth as a cohesive goldfilling, while such a surface is impossible with non-cohesive gold. Incavities which extend so far beyond the margin of the gum that it isimpossible to adjust the rubber-dam, I prepare the cavity as usual, thenadjust a matrix, disinfect, dry, and fill one-third full with tin andgold, then remove the matrix, apply the rubber, place matrix again inposition, and complete the filling by adding a little tin and gold, thenpure gold. " (Dr. W. A. Spring, _Dental Review_, February, 1896. )

Dr. T. D. Shumway says, "To have a scientific method of treatment, therecertainly must be a recognition of what is known of the nature oftooth-structure. The method adopted more than a quarter of a centuryago, and which is at present employed, does not accord with theteachings of the physiologist and microscopist; it is in directopposition to natural law. Each new discovery in the minute structure ofthe teeth makes this more plain; pounding the teeth with a mallet cannotbe defended on scientific grounds. That it has not resulted moredisastrously is due to the wonderful recuperative energy of nature torepair injury. No one would think of attempting to arrest and preventdisintegration in any other vital organ by abrasion. Why, then, inoperation on the teeth, should we reverse the plain, simple teaching ofnature? Placing cohesive gold against the dentinal walls by pounding itto heal a lesion is opposed to natural law. Cohesive gold will not bemastered by force; if compelled to yield by superior strength, it seeksa way to release itself; it is easily coaxed, but not easily driven. Cohesive gold will unite with tin at an insensible distance just ascohesive gold unites with itself; this union takes place without forceor pressure. Exactly what takes place when gold and tin are brought incontact in the way described we do not know; we can only say that thereappears to be a perfect union. When cohesive gold was introduced to theprofession, while it was softer than non-cohesive foil, it was found toresist under manipulation. This resistance is in accordance with thewell-known law that all crystalline bodies, when unobstructed, assume adefinite form. With gold the tendency is to a spherical form. Theprocess of crystallization is always from within outward. The mallet wasintroduced to overcome the resistance caused by the development of thecohesive property. Pounding gold with a mallet only increases itscrystallization. A crystalline body coming in contact with a fibrous onecan neither be antiseptic nor preservative; a filling-material whichpossesses these properties must be one that corresponds or is in harmonywith tooth-substance. 

"In the interglobular spaces there is a substance which is calledamorphous or structureless, and a filling to be in harmony with thissubstance should be amorphous or structureless in its composition. Theonly materials we have which meet these conditions are gutta-percha andtin. It is its structureless character that gives to tin its value. Coming in contact with the living dentin, it is easily adapted, and doesnot excite inflammation; it does not interfere with the process going onwithin the teeth to heal the lesion caused by caries. A wound from abullet made of tin, unless it struck a vital part, nature would heal, even if the cause of the wound was not removed, by encysting the ball. This process of nature of repairing injury by encysting the cause is ofinterest to the dentist in the study of suitable filling-materials. Tinis very useful at the cervical margin of cavities; it acts as anantiseptic or preservative, and reduces the liability to subsequentdecay. It is our endeavor to obtain a filling that will preserve theteeth and reduce the liability to, if not wholly prevent, secondarydecay. The law of correspondence is of more consequence than themechanical construction of the filling. Tin can be used without thatrigid adherence to mechanical rule that is necessary to retain a fillingof cohesive gold; thus less of the tooth needs to be sacrificed. 

"Gold will unite with tin under certain conditions so as to formapparently a solid mass. By a combination of these metals, not byinterlacing or incorporating one in the other, but by affinity, securedby simple contact, we have all the preservative qualities of tincombined with the indestructible properties of gold. For the base of thefilling we have a material in harmony with tooth-substance, introducedin a way that is in accord with the law that governs all living bodies, and for the outside a crystalline substance that corresponds to thecovering of the teeth. This covering of gold is a perfect shield to thebase, and the field for the display of artistic skill in restoringcontours is as broad as though gold was used entirely. Will a filling ofthis kind withstand mastication? There is in the economy of nature aprovision made to overcome the resistance of occlusion. The teeth arecushioned in the jaw and yield under pressure. The elasticity of thesubstance of which the teeth are made is well understood. Ivory is themost elastic substance known. The teeth coming together is like thepercussion of two billiard balls. Now a filling to save the teeth shouldcorrespond as nearly as possible with the tooth-substance; it should notbe arbitrary, but elastic and yielding. Tin is interdigitous; it expandslaterally, and is almost as easily introduced as amalgam, and when putin place does not have to be bound to be retained. Tin, with an outsidecovering of gold to protect it, makes a filling to which amalgam bearsno comparison. In the light of scientific investigation there can be butone method--a method based upon the recognized principle that the_filling-material_ and the _manner_ of _introducing_ it shall correspondto and be in harmony with the living, vital organism with which it comesin contact. 

"After excavating, the cavity is treated with absolute alcohol, ascleanliness and thorough dryness are absolutely essential. 

"The _tin_ is put in with steel pluggers, after the method of wedging;it must be thoroughly condensed, so as to leave a smooth surface, andenough used to come up to where the enamel and dentin join. 

"The effect is not produced by incorporating or interlacing the goldwith the tin; we rely upon the affinity of the two metals to retain thegold; no undercuts, angles, or pits are made in the tin, dentin, orenamel. The gold, extra cohesive from No. 4 to 40, is made to adhere tothe tin by simple contact, without pressure or force; the union is notmechanical. 

"The instruments used for filling the remainder of the cavity with goldare Shumway's ivory points, which adapt the gold nicely to the margin. 

"The set consists of five and were patented in 1881, and have been usedby me since that time for manipulating cohesive gold. One 'point' is forproximal cavities in the anterior teeth; three 'points' of differentsizes are for occlusal cavities; one 'point' for proximal cavities inbicuspids and molars and labial and buccal cavities; the sides, edges, and ends of the 'points' are used, as the purpose is simply to obtaincontact. 

"The 'point' shown full size in Fig. 8 is of more general applicationthan any of the others, and is used for proximal cavities in bicuspids, also labial and buccal cavities. The handle is made of ebony, and has asilver ferrule, from which the ivory extends to the end and completesthe instrument. 

"The metal pin in the end of the handle is for picking up and carryingthe gold. "

[Illustration: FIG. 8. ]

Tin has been used successfully for completely lining cavities, fillingthe remainder with gold; it is also useful for repairing gold fillings. 

Two or three thicknesses of tin foil may be pressed into a cavity with arubber point or hard piece of spunk, allowing it to come well out to themargin; filling the rest with amalgam. 

"As a lining it presents to dentin an amalgam of tin and mercury whichdoes not discolor the dentin like ordinary amalgam, and helps do awaywith local currents on the filling, which is one cause of amalgamshrinkage in the mouth. " (Dr. S. B. Palmer. )

When caries extends to the bifurcation of roots, make a mat of two orthree layers of tin, place it in the bifurcation and use it as a base infilling the rest of the cavity with amalgam. 

Tin is second in importance in alloys for amalgam, as it increasesplasticity, prevents discoloration, reduces conductivity and edgestrength, retards setting, favors spheroiding, therefore should not bethe controlling metal. 

It will be noticed that when cavities are lined with tin foil, it onlyconstitutes a small part of the filling, and that it has not been meltedwith the other metals in the alloy before being amalgamated. 

A thick mat of tin has been recommended as a partial non-conductor underamalgam fillings. 

Plastic tin can be made by pouring mercury into melted tin, or by mixingthe fillings with mercury at ordinary temperatures; it has a whitishcolor, and if there is not too much mercury it occurs in the form of abrittle granular mass of cubical crystals. Generally amalgams of tin andmercury do not harden sufficiently, but forty-eight parts of mercury andone hundred of tin make a fairly good filling, said to have atherapeutical value; it should not be washed or squeezed before using, and "is not a chemical combination. "

"Tin unites with mercury in atomic proportions, forming a weakcrystalline compound. " (Dr. E. C. Kirk. )

Mercury and tin readily unite as an amalgam under ordinarycircumstances, and form a definite chemical compound having the formulaSn_{2}Hg. (Hodgen. )

Another preparation of tin is known as stannous gold; it is manufacturedin heavy sheets and used the same as cohesive gold foil, and can beeasily manipulated, for it is rather plastic. 

Crystal tin for taking the place of tin foil:

"Take chemically pure hydrochloric acid and dissolve tin foil in ituntil a saturated solution is obtained; this may be done speedily byheating the acid to a boiling point, or the same thing can beaccomplished in a few hours with the acid cold; it is then chlorid oftin. It is then poured into a clean vessel and an equal quantity ofdistilled water added; then a clean strip of zinc is plunged into thesolution, and tin crystals are deposited on the zinc; when there issufficient thickness on the zinc, remove both, and slip the crystals offfrom the zinc into pure water, clean the zinc thoroughly, and reinsertfor another coating. The character of the crystallization will bemodified by the extent of the dilution of the solution in the firstplace. Wash the tin in pure water until all traces of the acid areremoved, or a few drops of ammonia can be added to neutralize the acid. It was suggested that it would be desirable to have some acid remain inthe tin for filling teeth in which there is no sensitive dentin. We haveput in a few fillings, and it works beautifully, and makes firmerfillings than foil. It must be kept in water (probably alcohol isbetter). It is pure tin, unites perfectly, and works easier than foil. "(Dr. Taft, _Dental Register of the West_, 1859. )

For some years it was considered the best practice to enlarge allroot-canals and fill them with gold; in many of these cases the crowncavities were filled with tin. 

Tin has been used for filling root-canals, but should there happen to beany leakage through the foramen or tooth-structure, the tin willdiscolor, and there may be infiltration into the crown, thus causingdiscoloration, which might be objectionable if the crown was filled withgold. Chloro-percha, gutta-percha, and oxychlorid of zinc are muchbetter for this purpose. 

The apical quarter of a canal has been filled with tin, and theremainder with cement. Tin can be used for filling root-canals. Roll ona broach small triangular pieces of the foil into very small cone-shapedcylinders, carry to place, then withdraw the broach, and force in thecylinder with the same or a larger broach; sometimes it is necessary touse another broach, to push the cylinder off from the one on which it isrolled. Another method is to carry and pack into the canal by means of abroach, very narrow strips of No. 10 or 20 foil; or the apical third ofthe canal could be filled with gold and the rest with tin. 

"About four years ago I concluded to try tin for filling root-canals;then I began to look for patients whose general health was good, who hadstrong, hardy-looking teeth, and kept their mouths in good condition. Ifound one who answered all my requirements, with a molar to be filled, and they would not have it filled with gold, or could not, on account ofthe expense. I filled the canals with tin and the crown with amalgam. After filling thirty-eight molars in this way I stopped fordevelopments. In six or seven weeks a lady returned with an inferiormolar abscessed, but at the time it was filled the circumstances weresuch that it could not be properly treated. In nine months a gentlemanfor whom I had filled four molars returned with an inferior oneabscessed. This is the sum-total of abscessed teeth where tin was usedin the root-canals, at the end of four years. The others are in goodcondition, as I have seen them every six months. The roots were treatedfrom four to six weeks with carbolic acid before filling. " (Dr. A. W. Harlan, _Missouri Dental Journal_, 1872. )

"Tin foil is just as good as gold for filling root-canals, as it isentirely innocuous and sufficiently indestructible, while its softnessand pliability commend it. Where gold is to be used for the crown, it isbetter to fill the bulbous portion of the pulp-cavity with gold also, soas to weld these portions of gold together. The success of Dr. Harlan'streatment was about equal to what might be expected from the same numberof teeth where the canals had been filled with gold. " (Editor, _MissouriJournal_. )

Shavings turned from a disk of pure tin have been used in combinationwith Watts's sponge gold for filling teeth, either by making a portionof the filling from each metal or using them indiscriminately. 

A mat of tin foil dipped in chloro-percha can be used to cap an exposedpulp, or a concave tin disk can be used for the same purpose. A mat oftin has been used over a slight exposure of the pulp, because of itsslight conduction of heat and cold, thus avoiding much thermalirritation and stimulating recuperation. 

Some use Robinson's fibrous material as a surface for tin fillings, thinking that it is harder and will wear longer because of the erroneousnotion that it has platinum in it. 

CHAPTER IX. 

Tin has been recommended for temporary fillings in sensitive cavities, because it is soft and easily packed in contact with the walls, hastherapeutic value, and after a time, when the temporary filling isremoved, the cavity is not as sensitive as formerly. 

It has been observed that starting gold in a sensitive cavity causespain, but starting tin in the same place seldom does. 

As long as tin preserves its integrity it preserves the tooth, thereforetin fillings should not be repaired with amalgam, as their integrity maybe destroyed. Cavities can be partly filled with tin and completed withsponge, fibrous, or crystalloid gold, after the manner described forbeginning with tin and finishing with gold foil. 

"I advocated tin at the cervical wall, cervico-lingual andcervico-buccal angles to the thickness of 24 plate. Then complete thefilling with gold. Some of my most successful efforts in saving softteeth have been made in this way. This method has great value over goldfor the whole filling, but there are two objections to it: First, itimparts to the cervical border the color and appearance of decay, sothat in three cases where an instrument passed readily into the tin Ihave removed the fillings, without any necessity for it, not evenfinding any softening of the margins. Second, its use requires the sameconditions of dryness, shape of cavity, delicate manipulation, inconvenience to patient, and strain upon the operator as when gold isused alone. " (Dr. D. D. Smith, _Dental Cosmos_, 1883. ) He admits thatthis method saves _soft_ teeth and also cervical margins. Do not thosetwo very important factors more than counterbalance the color, andoversight of the dentist?

Dryness is an essential in making the best filling with any material, and the time and strain consumed by the majority of operators in fillingwith tin is not more than one-half what it is in using gold. 

"I use tin at the cervical margin of all proximal cavities in bicuspidsand molars. I prepare a matrix of orange-wood to suit each case, lettingit cover about one-third of the cavity, then fill with tin condensed byhand force and automatic mallet; now split the matrix and carefullyremove it piece by piece, so as not to disturb the tin; then trim andfinish this part of the filling. Make another wooden matrix, whichcovers the tin and remainder of the cavity, and fit it snugly to place. Use a coarsely serrated plugger and begin packing non-cohesive goldinto the tin, letting it fill about one-third more of the cavity; thencomplete the last third (surface) with cohesive gold. I have tested thismethod for twenty years, and it has given me splendid results. I alwaystell patients that there will appear sooner or later a slightdiscoloration near the gum, which must not be mistaken for caries. " (Dr. A. P. Burkhart. )

Another use for tin in the operating-room is found in Screven's"Gutta-percha-coated Tin Foil, " a cohesive, antiseptic non-conductor, ofwhich the inventor says: "Cement fillings that have been kept dry forten hours after mixing will be much harder than those soon exposed tomoisture, and they will retain that hardness though exposed to moistureafterward. This preparation will keep a filling perfectly dry in themouth, and when removed the filling will be found hard as stone. Thereis nothing better for lining cavities, holding nerve-caps in position, holding a preparation in place when devitalizing a pulp where the toothis so much broken away as to make it difficult to prevent a fillingshowing through the enamel, and for many other purposes. "

High-heat gutta-percha has been used as a base in deep occlusal, buccal, and approximal cavities, completing the fillings with tin. Occlusalcavities may be filled with tin; then after the filling is condensed andfinished, drill out the center and fill with cohesive gold, not cuttingaway the tin so as to expose the margin; such fillings wear well, asmuch of the attritial force comes on the gold portion of the filling. 

With the exception of the part in brackets, the following article isfrom the _British Journal_, May, 1887:

"If a person eats an oyster stew at 130° F. , a gold filling would carrythe difference between the temperature of the stew and that of themouth, 130 - 98 = 32°, almost undiminished to the bottom of the cavity;allowing 2° of diminution, then the cavity around the gold filling hasassumed 128°; now the person feels warm and drinks ice-water at 32°. Taking into consideration the specific heat of the gold filling, it willassume about 40°, which it carries with a diminution of the cold ofabout 4°, --that is, as if it was 44°, --into the interior of the cavity;then the cavity will assume 44°, the difference within one-tenth of aminute being 128 - 44 = 84°, a change which would produce a violentinflammation in any organ which was not accustomed to it. Thisderangement in the tooth means interruption of circulation, and youngteeth will be most affected. 

"Thermal effect depends on heat-conducting power [gold is nearly fourtimes as good a conductor of heat as tin] and also on specific heat, sothe more the latter approaches that of the tooth the less it is liableto produce sudden changes [thus favoring tin]. Specific heat manifestsitself by the speed of changes, while the heat-conducting powerinfluences the intensity [then the intensity of heat in a gold fillingwould be three or four times as much as in a tin filling]. In speed goldproduces this change in one-tenth of a minute" [tin in one-fifth, --thatis, gold absorbs heat and expands about twice as fast as tin]. 

In 1838 Dr. J. D. White introduced sharp-wedge-shaped instruments forfilling teeth, and he claims to have been the first to use them; theypack laterally as well as downward, and present as small a surface tothe filling as possible, so that the greatest effect may be producedupon a given surface with a given power. Rolls of either tin or gold aremade by cutting any desirable portion from a sheet of No. 4 foil; cutthis portion once transversely, place on a napkin or piece of chamois, then with a spatula fold a very narrow portion of the edge once uponitself; then with the spatula resting on the thickened edge draw thespatula away from it with gentle pressure, and the foil will follow in aroll. 

[Illustration: FIG. 9. ]

The old method of using rolls, ropes, and tapes or strips is the same, but we will describe one method of using tapes. (See Fig. 9. ) A _strip_is a single thickness of foil in ribbon form; a strip folded lengthwiseonce, twice, or more forms a _tape_ of two, four, or more thicknesses offoil. The tin foil should be cut into strips and folded into tapesproportioned in width and thickness to the size of the cavity. One endof the tape is carried to the bottom of the cavity and then forcedagainst the side opposite the point where we intend to finish; nowremove the wedge-shaped plugger and catch the tape outside of thecavity, and fold another portion against that already introduced, letting all the folds extend from the bottom to a little beyond themargin. Proceed in this manner, with care and sufficient force, untilthe cavity is full, using for the last folds a small instrument. Condense the surface with a large plugger, then go over it carefullywith a small instrument, and if any part yields, force in a wedge-shapedplugger and fill the opening in above-described manner; condense, burnish, and trim alternately until the surface is level with thecavity-margin. By extending the folds from the orifice to the base ofthe cavity, the liability of the tin to crumble or come out iseffectually prevented, and by putting it in with a wedge-shaped pluggerit is pressed out into all depressions of the walls. 

A later method of filling with tape or rope is to use wedge-shapedpluggers with sharp serrations, filling the _ends_ of the cavity, and asthe two parts approach each other that next to the wall should be inadvance of the rest, thus an opening will be left in the center whichcan be filled with a smaller tape or rope. 

Another old method: Take a piece of foil and roll it into a hard ball;then gradually work it into the cavity, being careful to havesufficient around the margin. 

Still another suggested method: Roll a piece of foil into a loose ball, place it in the cavity, and pass a wedge-shaped plugger into its center. This has the effect of spreading the tin toward the walls of the cavity, the opening to be filled with folds in a way already described. Thewedge is used as often as it can be made to enter, filling each openingwith folds; then condense the surface, trim, and burnish. 

[Illustration: FIG. 10. ]

The English give the Americans the credit of first using cylinders. Anyhow, Dr. Clark, of New Orleans, in 1855, used them made fromnon-cohesive gold, and also from gold and tin in alternate layers. (SeeFig. 10. )

Cylinders were used which were a little longer than the depth of thecavity, introduced with wedge-shaped pluggers around the walls, each onebeing closely adapted to the margin; then another row was added, whichwas forced firmly against the preceding, continuing this process untilthe cavity was full. The wedge, having a smooth end and sides, is forcedinto the center so as to drive the tin toward the sides of the cavity, being careful not to split the tooth; the opening is then filled with acylinder. Now force a smaller-sized wedge into the center of the lastcylinder, and into the opening introduce another cylinder, proceeding inthis manner until the filling is solid. Then condense the ends of thecylinders, trim, and burnish. For the same operation more recentpluggers are wedge-shaped, with sharp, deep serrations. In these casesthe filling is retained by the general form of the cavity and wedgingwithin a certain limit, and not by cohesion of the different parts. Fora time tin cylinders were prepared and put on sale at the dental depots. 

As far as we are aware, the first tin foil made use of in operativetechnics was by Dr. F. S. Whitslar, who removed a disk of German silverfrom an ivory knife-handle in 1845, then used hand pressure to fill thecavity with tin. In the college course of operative technics tin foilcan be used, almost to the exclusion of gold foil, to demonstrate themanipulation of both cohesive and non-cohesive gold. Shavings scrapedfrom a bar of tin are also useful in operative technics; they are morecohesive than foil.