TEETH. 



fordes, which colkft upon the teeth, dimuiifli their glofs 

 and wliitenefs, and render them yellow or afli-coloured. 

 The cure confirts in removing tlic fordes. 



2. Dilcolouration from age. The wliitenefs and polifh 

 of the teeth, peculiar to youth, change in the advanced 

 period of life into a dull yellow, which is totally irre- 

 mediable. 



3. Difcolouration from the ufe of mercury. The teeth 

 are difcoloured not only by the internal, but alfo by the ex- 

 ternal ufe of mercury. Hence gilders, and other .irtizans 

 T7ho make ufe of mercury, have their teeth ftaincd of a 

 leaden colour. Plenck has feen the fame fort of disfigure- 

 ment occafioned by cofmetics containing quickfilver. 



The cure requires that the mercury be got out of the 

 fyftem as expeditioufly as poffiblc. 



4. Difcolouration from fcurvy, &c. Scorbutic perfons 

 are efpecially noticed as having the colour of the teeth 

 fpoiled. Venereal and ricketty fubjefts are alfo frequently 

 afFefted in the fame way. 



To this head muft likewlfe be referred the difcolouration 

 of the teeth obfervablc in mariners. 



5-. Difcolouration of the teeth from pregnancy. In preg- 

 nant and fuckling women, the luftre of the teeth is often 

 remarked to leflen, and thefe parts to be difcoloured. Lorry, 

 Tra£t. de Morb. Cutaneis, p. 61. 



It is fuppofed that this change of the teeth is frequently 

 connefted with the bad ftate of the milk, the evacuation and 

 correftion of which are the means of cure advifed by feveral 

 authors. 



6. Difcolouration from taking hot food. Perfons who 

 make a praftice of drinking very hot hquids, or of chew- 

 ing fubftances which are top warm, have the luftre and 

 whitenefs of their teeth deftroyed. It is queftionable, whe- 

 ther the beautiful white colour of the teeth of animals in 

 general may not be owing to their abftainmg from hot 

 aliments ? 



7. Difcolouration from dentifrice powders and tinftures 

 containing mineral acids. Thus, burnt alum and fpirit of 

 nitre for a (hort time whiten the teeth ; but a little while 

 afterwards, the enamel turns pale and falls off in bits. 



8. Difcolouration from the fmoke of tobacco. The oil 

 of this plant is well known to have the effeft of turning the 

 colour of the teeth to a dark brown or black. 



9. Difcolouration from thinnefs of the enamel. When 

 the vitreous fubftance is in a certain degree worn away, the 

 bony fubftance, which is yellow, can be feen through it. 

 The defeft is incurable. 



10. Difcolouration from an internal caries of the tooth. 

 Such a tooth lofes its luftre and whitenefs, and becomes 

 pale, afti-coloured, dark-brown, and at length black. 



Here the only mode of cure is to extraft the difeafed 

 t®oth. 



11. Difcolouration from the ufe of madder. It is re- 

 marked, that only the bony part of the tooth is ftained red 

 by this root, but not the enamel. The rednefs alfo does not 

 extend itfelf to the portion of the tooth already formed ; but 

 only to the part formed while the animal is fed with madder. 

 This coloi:r hkewife never difappears : circumftances much 

 againft the doftrine of the teeth being vafcular. 



12. Golden difcolouration of the teeth. This fpecies is 

 brought on by art. 



Fragility of the Teeth, — In this affeftion, the cohefion of 

 the fubftance of the teeth is fo flight, that a very inconfi- 

 derable force makes it break. 



The proximate caufe of this fragility of the teeth is pro- 

 bably connefted, in many examples, with fome imperfeftions 

 sn their original growth. 



The varieties defcribed by writers are as follow : 

 Vol. XXXV. 



1. The fcprbutie fragility. In people affliAcd with the 

 fcurvy, the bodies of the teeth by degrees become fo fragile 

 that they drop out piccon1e.1l. 



2. Fragility from rickets. In children thus affefted, the 

 milk-teeth, foon after they have been cut, become dark- 

 coloured, are cafily broken, .ind ufually fall out in pieces. 



3. Fragility from old age. In old age the teeth .ve apt 

 to be broken in biting With force, and to fall out piece- 

 meal. 



4. Fragility from the application of mineral acids or 

 burning oils. The abufe of fuch medicines, too long con- 

 tinued, brings on a fpecies of fragility, which admits of no 

 mode of cure. 



5. Fragility from caries. Teeth, which are excavated 

 by caries, and rendered thin, are readily broken in mallica- 

 tion, and drop out in jiieces. 



All the difl'erent fpecies of fragility arc incurable. 



MoUilies, or Pretcriuiturjl Softncfs of the Teeth. — This dif- 

 eafe is fo remarkable a foftnefs of the fubftance of the teeth, 

 that it can almoll becompreircd together by the fingers. 



The proximate caufe is faid to be either too great a 

 quantity of the gluten, which connects the earthy particles 

 together, or elfe a deficiency of tlie earth. 



The fpecies arc : 



1. Softncfs of a milk-tooth. Plenck extrailcd from a 

 girl fevcn years of age, a canine milk-tooth of th« lower 

 jaw, which was livid and foft, like cartilage, and was com- 

 preflible by the fingers, efpecially at the fang. Dc Morb. 

 Dentium, p. 39. 



2. Softnefs of the teeth from farcoftofis of the fang. 

 Sometimes the fang of a tooth is abforbed, and a fungous 

 fubftance fills up its place. This cafe has been abfurdly in- 

 ftanced as a fpecimen of mollities of the teeth. 



3. Softnefs of the teeth from fcurvy. It is aflertcd, that 

 in the fcurvy, the teeth have been fometimes fofteiTcd and 

 enlai-ged. (Grainger Hift. Febris Anom. p. 6.) But fuch 

 accounts muft be incorred, fince they imply a vafcular or- 

 ganization of the teeth. It merits attention alfo, that in 

 certain dead fubjcCls, whofe bones are all affetled with mol- 

 hties, the teeth are found pcrfeftly hard. 



Preternatural Angles, or Sharpnefs of the Teeth. — Some- 

 times the form of a tooth is fo acute, that it hurts the 

 neighbouring parts by pricking them. 



The effefts of fuch a tooth are irritation of the tongue, 

 or of the inner furface of the lips, or check. Hence in- 

 flammation of thefe parts, or an ill-conditioned ulcer oppofif e 

 the ftiarp portion ot the tooth, curabla by no means Vrlir.t- 

 foever, except the removal of the angle or fli.vpnefs. 



The fpecies are afcribablc to the particularity of the 

 caufe. 



1. Irritating angles, or (liarpnefs from malformation of a 

 tooth. In this caie the tooth has a found appearance, and 

 the crown is felt to be too pointed or (harp. 



2. Irritating angles, or Iharpncfs from an oblique frac- 

 ture of a tooth ; as fometimes happens from biting hard 

 nuts and other fubftances. The cafe can be detcitcd on 

 ocular examination, 



3. Irritating angles, or fharpnefs from the tooth being 

 worn obliquely. This is the moft common cafe. 



The cure requires that the pointed or (harp part of t!ic 

 tooth be removed cither with a file or a pair of cutting 

 forceps ; but if this cannot be acconiplilhed, the tooth 

 (hould be pulled out. 



Fradurcs of the Teeth. — A frafture of a tooth is a folu- 

 tion of it into two or more fragments. 



The folution of continuity may be tranfvcrfc, oblique, or 

 comminuted. The moft common kind of fraAure is the ft- 

 paration of a particle of the enamel from the reft. 



C c The 



