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DENTISTRY (from Lat. dens, a tooth)

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Originally appearing in Volume V08, Page 54 of the 1911 Encyclopedia Britannica.
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DENTISTRY (from See also:Lat. See also:dens, a tooth)  , a See also:special See also:department of medical See also:science, embracing the structure, See also:function and See also:Historical See also:therapeutics of the mouth and its contained See also:organs, See also:sketch. specifically the See also:teeth, together with their surgical and prosthetic treatment . (For the See also:anatomy of the teeth see TEETH.) As a distinct vocation it is first alluded to by See also:Herodotus (500 B.C.) . There are evidences that at an earlier date the Egyptians and See also:Hindus attempted to replace lost teeth by attaching See also:wood or See also:ivory substitutes to adjacent See also:sound teeth by means of threads or wires, but the See also:gold fillings reputed to have been found in the teeth of See also:Egyptian mummies have upon investigation been shown to be superficial applications of gold See also:leaf for ornamental purposes . The impetus given to medical study in the Grecian See also:schools by the followers of See also:Aesculapius and especially See also:Hippocrates (500 to 400 B.C.) See also:developed among the practitioners of See also:medicine and See also:surgery considerable knowledge of See also:dentistry . See also:Galen (A.D . 131) taught that the teeth were true bones existing before See also:birth, and to him is credited the belief that the upper canine teeth receive branches from the See also:nerve which supplies the See also:eye, and hence should be called " eye-teeth." Abulcasis (loth cent . A.D.) describes the operation by which artificial crowns are attached to adjacent sound teeth . Vesalius (1514), Ambroise See also:Pare, J . J . See also:Scaliger, T . Kerckring, M . See also:Malpighi, and lesser anatomists of the same See also:period contributed See also:dissertations which threw some small amount of See also:light upon the structure and functions of the teeth .

The operation of transplanting teeth is usually attributed to See also:

John See also:Hunter (1728-1793), who practised it extensively, and gave to it additional prominence by transplantinga human tooth to the See also:comb of a See also:cock, but the operation was alluded to by Ambroise Pare (1509-1590), and there is See also:evidence to show that it was practised even earlier . A. von See also:Leeuwenhoek in 1678 described with much accuracy the tubular structure of the dentine, thus making the most important contribution to the subject which had appeared up to that See also:time . Until the latter See also:part of the 18th See also:century extraction was practically the only operation for the cure of toothache . The See also:early contributions of See also:France exerted a controlling See also:influence upon the development of dental practice . Urbain Hemard, surgeon to the See also:cardinal Georges of See also:Armagnac, whom Dr See also:Blake (1801) calls an ingenious surgeon and a See also:great See also:man, published in 1582 his Researches upon the Anatomy of the Teeth, their Nature and Properties . Of Hemard, M . Fauchard says: " This surgeon had read See also:Greek and Latin authors, whose writings he has judiciously incorporated in his own See also:works." In 1728 Fauchard, who has been called the See also:father of See also:modern dentistry, published his celebrated See also:work, entitled Le Chirurgien Dentiste ou traite See also:des dents . The See also:preface contains the following statement as to the existing status of dental See also:art and science in France, which might have been applied with equal truth to any other See also:European See also:country:—" The most celebrated surgeons having abandoned this See also:branch of surgery, or having but little cultivated it, their See also:negligence gave rise to a class of persons who, without theoretic knowledge or experience, and without being qualified, practised it at See also:hazard, having neither principles nor See also:system . It was only since the See also:year 1700 that the intelligent in See also:Paris opened their eyes to these abuses, when it was provided that those who intended practising dental surgery should submit to an examination by men learned in all the branches of medical science, who should decide upon their merits." After the publication of Fauchard's work the practice of dentistry became more specialized and distinctly separated from medical practice, the best exponents of the art being trained as apprentices by practitioners of ability, who had acquired their training in the same way from their predecessors . Fauchard suggested See also:porcelain as an improvement upon See also:bone and ivory for the manufacture of artificial teeth, a See also:suggestion which he obtained from R . A . F. de See also:Reaumur, the See also:French savant and physicist, who was a contributor to the royal porcelain manufactory at Sevres .

Later, Duchateau, an See also:

apothecary of St Germain, made porcelain teeth, and communicated his See also:discovery to the See also:Academy of Surgery in 1776, but kept the See also:process See also:secret . Du Bois Chemant carried the art to See also:England, and the process was finally made public by M . Du Bois Foucou . M . Fonzi improved the art to such an extent that the See also:Athenaeum of Arts in Paris awarded him a See also:medal and See also:crown (See also:March 14, 1808) . In Great See also:Britain the 19th century brought the dawning of dental science . The work of Dr Blake in 18or on the anatomy of the teeth was distinctly in advance of anything previously written on the subject . See also:Joseph See also:Fox was one of the first members of the medical profession to devote himself exclusively to dentistry, and his work is a repository of the best practice of his time . The processes described, though comparatively crude, involve principles in use at the See also:present time . See also:Thomas See also:Bell, the successor of Fox as lecturer on the structure and disease of the teeth at See also:Guy's See also:Hospital, published his well-known work in 1829 . About this period numerous publications on dentistry made their See also:appearance, notably those of Koecker, See also:Johnson and See also:Waite, followed somewhat later by the admirable work of See also:Alexander See also:Nasmyth (1839) . By this time See also:Cuvier, See also:Serres, See also:Rousseau, See also:Bertin, Herissant and others in France had added to the knowledge of human and See also:comparative dental anatomy, while M .

G . Retzius, of See also:

Sweden, and E . H . See also:Weber, J . C . Rosenmuller, Schreger, J . E. von Purkinje, B . Fraenkel and J . See also:Muller in See also:Germany were carrying forward the same lines of See also:research . The sympathetic See also:nervous relationships of the teeth with other parts of the See also:body, and the interaction of diseases of the teeth with See also:general pathological conditions, were clearly established . Thus a scientific See also:foundation was laid, and dentistry came to be practised as a specialty of medicine . Certain See also:minor operations, however, such as the extraction of teeth and the stopping of See also:caries in an imperfect way, were still practised by barbers, and, the empirical practice of dentistry, especially of those operations which were almost wholly See also:mechanical, had developed a considerable body of dental artisans who, though without medical See also:education in many cases, possessed a high degree of manipulative skill .

Thus there came to be two classes of practitioners, the first regarding dentistry as a specialty of medicine, the latter as a distinct and See also:

separate calling . In See also:America representatives of both classes of dentists began to arrive from England and France about the time of the Revolution . Among these were John Wooffendale (1766), a student of See also:Robert Berdmore of See also:Liverpool, surgeon-dentist to See also:George III.; See also:James Gardette (1778), a French physician and surgeon; and Joseph Lemaire (1781), a French dentist who went out with the See also:army of See also:Count See also:Rochambeau . During the See also:winter of 1781–1782, while the See also:Continental army was in winter quarters at See also:Providence, Rhode See also:Island, Lemaire found time and opportunity to practise his calling, and also to instruct one or two persons, notably See also:Josiah Flagg, probably the first See also:American dentist . Dental practice was thus established upon American See also:soil, where it has produced such fertile results . Until well into the 19th century See also:apprenticeship afforded the only means of acquiring a knowledge of dentistry . The profits derived from the, apprenticeship system fostered secrecy and quackery among many of the early practitioners; but the more liberal minded and better educated of the See also:craft developed an increasing opposition to these narrow methods . In 1837 a See also:local association of dentists was formed in New See also:York, and in Course of 184o a See also:national association, The American Society of training . Dental Surgeons, the See also:object of which was " to advance the science by See also:free communication and interchange of senti- ments." The first dental periodical in the See also:world, The American See also:Journal of Dental Science, was issued in See also:June 1839, and in See also:November 1840 was established the See also:Baltimore See also:College of Dental Surgery, the first college in the world for the systematic education of dentists . Thus the year 1839–1840 marks the birth of the three factors essential to professional growth in dentistry . All this, combined with the refusal of the medical schools to furnish the desired facilities for dental instruction, placed dentistry for the time being upon a footing entirely separate from general medicine . Since then the curriculum of study preparatory to dental practice has been systematically increased both as to its content and length, until in all fundamental principles it is practically equal to that required for the training of medical specialists, and in addition includes the technical subjects See also:peculiar to dentistry .

In England, and to some extent upon the See also:

continent, the old apprenticeship system is retained as an See also:adjunct to the college course, but it is rapidly dying out, as it has already done in America . Owing to the regulation by See also:law of the educational requirements, the increase of institutions devoted to the professional training of dentists has been rapid in all civilized countries, and during the past twenty years especially so in the See also:United States . Great Britain possesses upwards of twelve institutions for dental instruction, France two, Germany and See also:Switzerland six, all being based upon the conception that dentistry is a department of general medicine . In the United States there were in 1878 twelve dental schools, with about 70o students; in 1907 there were fifty-seven schools, with 6919 students . Of these fifty-seven schools, See also:thirty-seven are depart- ments of See also:universities or of medical institutions, and there is a growing tendency to regard dentistry from its educational aspect as a special department of the general medical and surgical practice . See also:Recent studies have shown that besides being an important part of the See also:digestive system, the mouth sustains intimate re- lationship with the general nervous system, and is important as the portal of entrance for the See also:majority of the bacteria that cause specific diseases . This fact has rendered more intimate the relations between dentistry and the general practice of medicine, and has given a powerful impetus to scientific studies in dentistry . Through the researches of See also:Sir J . Tomes, Mummery, Research . Hopewell See also:Smith, See also:Williams and others in England, O . Hertwig, Weil and See also:Rose in Germany, See also:Andrews, Sudduth and See also:Black in America, the See also:minute anatomy and See also:embryology of the dental tissues have been worked out with great fulness and precision . In particular, it has been demonstrated that certain general systemic diseases have a distinct oral expression .

Through their extensive nervous connexions with the largest of the See also:

cranial nerves and with the sympathetic nervous system, the teeth frequently cause irritation resulting in profound reflex nervous phenomena, which are curable only by removal of the local tooth disorder . See also:Gout, lithaemia, See also:scurvy, See also:rickets, See also:lead and See also:mercurial poisoning, and certain forms of chronic nephritis, produce dental and oral lesions which are either pathognomonic or strongly indicative of their several constitutional causes, and are thus of great importance in diagnosis . The most important dental re-See also:search of modern times is that which was carried out by See also:Professor W . D . See also:Miller of See also:Berlin (1884) upon the cause of caries of the teeth, a disease said to affect the human See also:race more extensively than any other . Miller demonstrated that, as previous observers had suspected, caries is of bacterial origin, and that acids See also:play an important role in the process . The disease is brought about by a See also:group of bacteria which develop in the mouth, growing naturally upon the debris of starchy or See also:carbohydrate See also:food, producing See also:fermentation of the See also:mass, with lactic See also:acid as the end product . The lactic acid dissolves the See also:mineral constituent of the tooth structure, See also:calcium phosphate, leaving the organic See also:matrix of the tooth exposed . Another class of germs, the peptonising and putrefactive bacteria, then convert the organic See also:matter into liquid or gaseous end products . The accuracy of the conclusions obtained from his See also:analytic research was synthetically proved, after the manner of See also:Koch, by producing the disease artificially . Caries of the teeth has been shown to See also:bear highly important relation to more remote or systemic diseases . Exposure and See also:death of the dental pulp furnishes an See also:avenue of entrance for disease-producing bacteria, by which invasion of the deeper tissues may readily take See also:place, causing See also:necrosis, See also:tuberculosis, See also:actinomycosis, phlegmon and other destructive inflammations, certain of which, affecting the various sinuses of the See also:head, have been found to cause See also:meningitis, chronic See also:empyema, metastatic abscesses in remote parts of the body, See also:paralysis, See also:epilepsy and See also:insanity .

Operative Dentistry.—The art of dentistry is usually divided arbitrarily into operative dentistry, the purpose of which is to preserve as far as possible the teeth and associated tissues, and prosthetic dentistry, the purpose of which is to See also:

supply the loss of teeth by artificial substitutes . The filling of carious cavities was probably first performed with lead, sug- Fttltng or stopping . gested apparently by an operation recorded by See also:Celsus (100 B.C.), who recommended that frail or decayed teeth be stuffed with lead previous to extraction, in See also:order that they might not break under the forceps . The use of lead as a filling was sufficiently prevalent in France during the 17th century to bring into use the word plombage, which is still occasionally applied in that country to the operation of filling . Gold as a filling material came into general use about the beginning of the 19th century.' The earlier preparations of gold were so impure as to be virtually without cohesion, so that they were of use only in cavities which had sound walls for its retention . In the See also:form of rolls or tape it was forced into the previously cleaned and prepared cavity, condensed with See also:instruments under heavy See also:hand pressure, smoothed with files, and finally burnished . See also:Tin See also:foil was also used to a limited extent and by the same method . Improvements in the refining of gold for dental use brought the product to a See also:fair degree of purity, and, about 1855, led to the invention by Dr Robert See also:Arthur of Baltimore of a method by which it could be welded firmly within the cavity . The cohesive properties of the foil were developed by passing it through an See also:alcohol See also:flame, which dispelled its See also:surface contaminations . The gold was then welded piece by piece into a homogeneous mass by plugging instruments with serrated points . In this process of See also:cold-See also:welding, the See also:mallet, hitherto in only limited use, was found more efficient than hand pressure, and was rapidly developed . The See also:primitive mallet of wood, ivory, lead or See also:steel, was supplanted by a mallet in which ' The filling of teeth with gold foil is recorded in the See also:oldest known See also:book on dentistry, Artzney Buchlein, published anonymously in 153o, in which the operation is quoted from Mesue (A.D .

857), physician to the See also:

caliph Haroun al-Raschid . a See also:hammer was released automatically by a See also:spring condensed by pressure of the operator's hand . Then followed mallets operated by pneumatic pressure, by the dental See also:engine, and finally by the electro-magnet, as utilized in 1867 by Bonwill . These devices greatly facilitated the operation, and made possible a partial or entire restoration of the tooth-crown in conformity with anatomical lines . The dental engine in its several forms is the outgrowth of the See also:simple See also:drill worked by the hand of the operator . It is used in removing decayed structure and for shaping the cavity for inserting the filling . From time to time its usefulness has been extended, so that it is now used for See also:finishing fillings and polishing them, for polishing the teeth, removing deposits from them and changing their shapes . Its latest development, the dento-surgical engine, is of heavier construction and is adapted to operations upon all of the bones, a recent addition to its equipment being the See also:spiral osteotome of Cryer, by which, with a minimum See also:shock to the patient, fenestrae of any See also:size or shape in the See also:brain-See also:case may be made, from a simple trepanning operation to the more extensive openings required in See also:intra-cranial operations . The rotary See also:power may be supplied by the See also:foot of the operator, or by See also:hydraulic or electric See also:motors . The See also:rubber See also:dam invented by S . C . See also:Barnum of New York (1864) provided a means for protecting the See also:field of operations from the oral fluids, and extended the See also:scope of operations even to the entire restoration of tooth-crowns with cohesive gold foil .

Phoenix-squares

Its value has been found to be even greater than was at first anticipated . In all operations involving the exposed dental pulp or the pulp-chamber and See also:

root-canals, it is the only efficient method of mechanically protecting the field of operation from invasion by disease-producing bacteria . The difficulty and annoyance attending the insertion of gold, its high thermal conductivity, and its objectionable See also:colour have led to an increasing use of See also:amalgam, guttapercha, and cements of See also:zinc See also:oxide mixed with zinc chloride or phosphoric acid . Recently much See also:attention has been devoted to restorations with porcelain . A piece of See also:platinum foil of •oo1 See also:inch thickness is burnished and pressed into the cavity, so that a matrix is produced exactly fitting the cavity . Into this matrix is placed a mixture of powdered porcelain and See also:water or alcohol, of the colour to match the tooth . The mass is carefully dried and then fused until homogeneous . Shrinkage is counteracted by additions of porcelain See also:powder, which are repeatedly fused until the whole exactly fills the matrix . After cooling, the matrix is stripped away and the porcelain is cemented into the cavity . When the See also:cement has hardened, the surface of the porcelain is ground and polished to proper See also:contour . If successfully made, porcelain fillings are scarcely noticeable . Their durability remains to be tested .

Until recent times the exposure of the dental pulp inevitably led to its death and disintegration, and, by invasion of bacteria via the pulp See also:

canal, set up an inflammatory process which eventually caused the loss of the entire tooth . A rational system of therapeutics, in See also:conjunction with proper antiseptic See also:measures, has made possible both the conservative treatment of the dental pulp when exposed, and the successful treatment of pulp-canals when the pulp has been devitalized either by See also:design or disease . The conservation of the exposed pulp is affected by the operation of capping . In capping a pulp, irritation is allayed by antiseptic and sedative treatment, and a metallic cap, lined with a non-irritant sedative See also:paste, is applied under aseptic conditions immediately over the point of pulp exposure . A filling of cement is superimposed, and this, after it has hardened, is covered with a metallic or other suitable filling . The utility of arsenious acid for devitalizing the dental pulp was discovered by J . R . Spooner of See also:Montreal, and first published in 1836 by his See also:brother Shearjashub in his See also:Guide to Sound Teeth . The painful See also:action of See also:arsenic upon the pulp was avoided by the addition of various sedative drugs,—morphia, atropia, See also:iodoform, &c.,—and its use soon became universal . Of See also:late years it is being gradually supplanted by immediate surgical extirpation under the benumbing effect of See also:cocaine salts . By the use of cocaine also the See also:pain incident to excavating and shaping of cavities in tooth structure may be controlled, especially when the cocaine is driven into the dentine by means of an electric current . To fill the pulp-chamber and canals of teeth after loss of the pulp, all organic remains of pulp See also:tissue should be removed by sterilization, and then, in order to prevent the entrance of bacteria, and consequent infection, the canals should be perfectly filled .

Upon the exclusion of infection depends the- future integrity and comfort of the tooth . Numberless methods have been invented for the operation . Pulpless teeth are thus pre-served through See also:

long periods of usefulness, and even those remains of teeth in which the crowns have been lost are rendered comfortable and useful as supports for artificial crowns, and as abutments for assemblages of crowns, known as See also:bridge-work . The discoloration of the pulpless tooth through putrefactive changes in its organic matter were first overcome by See also:bleaching it with See also:chlorine . Small quantities of calcium hypochlorite are packed into the pulp-chamber and moistened with dilute acetic acid; the decomposition of the calcium See also:salt liberates chlorine in situ, which restores the tooth to normal colour in a See also:short time . The cavity is afterwards washed out, carefully dried, lined with a light-coloured cement and filled . More efficient bleaching agents of recent introduction are See also:hydrogen dioxide in a 25% See also:solution or a saturated solution of See also:sodium peroxide; they are less irritating and much more convenient in application . Unlike chlorine, these do not form soluble metallic salts which may subsequently discolour the tooth . Hydrogen dioxide may be carried into the tooth structure by the electric current . In which case a current of not less than See also:forty volts controlled by a suitable graduated resistance is applied with the patient in See also:circuit, the anode being a platinum-pointed electrode in contact with the dioxide solution in the tooth cavity, and the See also:cathode a sponge or See also:plate electrode in contact with the hand or See also:arm of the patient . The current is gradually turned on until two or three milliamperes are indicated by a suitable ammeter . The operation requires usually twenty to thirty minutes .

Mal.posed teeth are not only unsightly but prone to disease, and may be the cause of disease in other teeth, or of the associated tissues . The impairment of function which their abnormal position causes has been found to be the See also:

primary cause of disturbances of the general bodily See also:health; for example, enlarged tonsils, chronic See also:pharyngitis and nasal See also:catarrh, indigestion and malnutrition . By the use of springs, screws, vulcanized caoutchouc bands, elastic ligatures, &c., as the case may require, practically all forms of dental irregularity maybe corrected, even such protrusions and retrusions of the front teeth as cause great disfigurement of the facial contour . The extraction of teeth, an operation which until quite recent times was one of the crudest procedures in minor surgery, has been reduced to exactitude by improved instruments, designed with reference to the anatomical relations of 6xtrac . See also:floe . the teeth and their alveoli, and therefore adapted to the several classes of teeth . The operation has been rendered painless by the use of anaesthetics . The anaesthetic generally employed is nitrous oxide, or laughing-See also:gas, the use of which was discovered in 1844 by See also:Horace See also:Wells, a dentist of See also:Hartford, See also:Conn., U.S.A . See also:Chloroform and See also:ether, as well as other general anaesthetics, have been employed in extensive operations because of their more See also:pro-longed effect; but chloroform, especially, is dangerous, owing to its effect upon the See also:heart, which in many instances has suddenly failed during the operation . Ether, while less manageable than nitrous oxide, has been found to be practically devoid of danger . The local injection of solutions of cocaine and allied anaesthetics into the See also:gum-tissue is extensively practised; but is attended with danger, from the toxic effects of an overdose upon the heart, and the local poisono