Tin Foil and Its Combinations for Filling Teeth Part 1

Tin Foil and Its Combinations for Filling Teeth.

by Henry L. Ambler.

PREFACE.

Believing that sufficient and well-deserved prominence was not being given to the use of tin foil and its combinations, the author decided to present a brief historical resume of the subject, together with such practical information as he possesses, before the profession in order that it may have the satisfaction of saving more teeth, since that is the pre-eminent function of the modern dentist. One object is to meet the demand for information in regard to the properties and uses of tin foil; this information has been sought to be given in the simplest form consistent with scientific accuracy. The present use of tin is a case of the "survival of the fittest," because tin was used for filling teeth more than one hundred years ago. There is not a large amount of literature upon the subject, and no single text-book has treated the matter fully enough to answer the needs of both teacher and pupil. It is difficult for the student to collect and harmonize from the many different sources just the kind and amount of information required for his special use. Perhaps this work will be of a.s.sistance to scientific students and practical operators in the art of using tin foil, including all who wish in compact form an explanation of the facts and principles upon which the art is based. A good method to arouse in students an interest in the use of tin foil is to have them use it in operative technics, which is becoming an effective adjunct in every dental college. By this means a great factor will be brought to bear, and the result will be that hundreds of graduates every year will begin practice better qualified to save teeth than if they had not known whatever may be learned about this material. At the University of Pennsylvania, Department of Dentistry, session 1896-97, out of the total number of fillings made in the clinical department (fractions omitted) 55 per cent. were gold, 15 per cent. tin, 10 per cent. amalgam. This shows that tin has some very strong friends in the persons of Professors Darby and Kirk.

The historical sketch of the development of the subject is arranged in chronological order, and is given partly to show that some old ideas and methods were good, and some obviously incorrect when viewed in the light of more recent developments. Part of the history will be new to the oldest members of the profession, and the younger ones will certainly read it with interest. The work has been brought up to date by considering all the properties and methods available. More names, good opinions, and dates could have been given, but the writer believes that what is herein presented is enough to thoroughly substantiate his own opinions, experiments, and practical applications. Some of the ill.u.s.trations have been made especially for this work; the others have been obtained through the courtesy of the owners.

"Let not the foggy doctrine of the superiority of gold in all cases act on progress as the old medieval superst.i.tions acted on astronomy, physiology, zoology. Truth sought after without misgiving, and the humblest as well as the highest evidence taken in every case, and acted on with skill and discrimination, will crown all with a high average of success."

It is hoped that what has been said in this volume will enable those who study it to save more teeth, and stimulate them to make improvements on the material and methods, doing much better than has been described or suggested.

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 quant.i.ty of tin foil used measures the number of teeth saved with _metals_ in any country during any historical period.

CHAPTER I.

Moses, who was born 1600 B.C., mentions tin, and history records its use 500 B.C., but not for filling teeth; much later on, the Ph[oe]nicians took it from Cornwall, England, to Tyre and Sidon.

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

Hindoo native doctors give tin salts for urinary affections. Monroe, Fothergill, and Richter claim to have expelled worms from the human system, 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 t.i.thingmen in England for liberty to dig in the tin-mines.

In 1846, Tin (Stannum, symbol Sn) was found in the United States only at Jackson, N. H. Since then it has been found, to a limited extent, in West Virginia and adjoining parts of Ohio, North Carolina, Utah, and North Dakota. The richest tin mines of the world, however, are in Cornwall, England, which have been worked from the time of the Ph[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 alluvial deposits in the form of small rounded grains, which are washed, stamped, mixed with slag and scoriae, and smelted with charcoal, then run into basins, where the upper portion, after being removed, is known as the best refined tin. Stream tin is not pure metallic tin, but is the result of the disintegration of granitic and other rocks which contain veins of tinstone. Banca tin is 99.961 parts tin, 0.019 iron, 0.014 lead in 100 parts; it is sold in blocks of 40 and 120 pounds, and a bar 0.5 meter long, 0.1 broad, 0.005 deep can be bent seventy-four times without being broken. Subjected to friction, tin emits a characteristic odor.

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

Pure tin may be precipitated in quadratic crystals by a slight galvanic current excited by immersing a plate of tin in a strong solution of stannous chlorid; water is carefully poured in so as not to disturb the layer of tin solution; the pure metal will be deposited on the plate of tin, 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 it expedient to consider some of its physical characteristics, in order that what follows may be more clearly understood.

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

The specific gravity is 7.29; electrical state positive; fusing point 442 F.; tensile strength per square inch in tons, 2 to 3. Tensile strength is the resistance of the fibers or particles of a body to separation, so that the amount stated is the weight or power required to tear asunder a bar of pure tin having a cross-section of one square inch.

Tenacity: Iron is the most tenacious of metals. To pull asunder an iron wire 0.787 of a line in diameter requires a weight of 549 lbs. To pull asunder a gold wire of the same size, 150 lbs.; tin wire, 34 lbs.; gold being 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 a millimeter thick, thus requiring 1020 to make an inch in thickness.

Miller states that it can be beaten into leaves .008 of a millimeter thick, thus requiring 3175 to make an inch in thickness. Richardson says that ordinary tin foil is about 0.001 of an inch in thickness.

If the difficulty with which a ma.s.s of gold (the most malleable of metals) 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 manipulate tin into thin sheets.

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

Among the metals, silver is the best conductor of heat. If the conductivity of silver be taken as 100, then the conducting power of gold would be 53.2; tin, 14.5; gold being thus shown to be nearly four times as good a conductor of heat as tin. Among the metals, silver is the best conductor of electricity. If its electrical conductivity be taken 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 a conductor of electricity as tin.

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

As to linear expansion, when raised from 32 to 212 F., aluminum expands the most of any of the metals. Taking its expansion as 1, that of tin would be 3, _i.e._, aluminum expands three times as much as tin.

(Dixon, "Vade Mec.u.m.")

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

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

Tin has a scale hardness of about 4, on a scale of 12 where lead is taken as the softest and platinum the hardest. (Dixon, "Vade Mec.u.m.")

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

To fuse a tin wire one centimeter in diameter requires a fusing current of electricity of 405.5 amperes. Up to 225 C., the rise in resistance to the pa.s.sage 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 be distilled.

CHAPTER II.

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

"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, which lasted for a good number of years." ("A Practical and Domestic Treatise on Teeth and Gums," by Mr. Sigmond, Bath, England, 1825.)