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ORIGINAL COMMUNICATIONS. 



On Certain Conditions of the Dental Tissues. By John 

 Tomes, F.R.S., Surg-eon-Dentist to the Middlesex Hospital. 



The temporary teeth, when about to be replaced by the per- 

 manent set, lose their fangs by gradual absorption of their 

 substance. Tlie crown, when thus left, having but little hold 

 upon the gum, soon falls out. The manner in which the 

 absorption of the dental tissues is effected has been described 

 in a paper published in the " Philosophical Transactions," in 

 1853. The subject is there mentioned in connection with the 

 absorption of bone. 



Having latterly had occasion to devote considerable attention 

 to the phenomena attending tlie casting off of the deciduous 

 teeth, several conditions relative to absorption have come 

 under my notice, which, as applied to teeth, had, I think, 

 hitherto escaped observation. It may, however, be here 

 stated, that the more recent examinations have not led to any 

 modification of the opinions upon the subject of absorption 

 advanced in the paper alluded to, but have served rather to 

 confirm the statement there made. Absorption may com- 

 mence upon any part of the fangs of a tooth, and at several 

 points at tlie same time. By the gradual extensif)n of this 

 process, both in depth and snperfic ially, the root of the tooth 

 is wasted, till, at last, nothing is left but the crown, and even 

 this part is often so much hollowed out, that, excepting the 

 enamel, but little of the tooth remains. The cementum is 

 first attacked, then the dentine disappears, and the enamel at 

 those points where the dentine has been entirely removed 

 suffers from the same action. But whichever of the three 

 tissues is attacked, we see the same characteristic surface as 

 that shown by bone when undergoing a similar action, namely, 

 a surface full of deep indentations, as though they had been 

 made by a sharp piercing instrument, having a semicircular 

 extremity. These minute holes or depressions proceed in 

 various directions, several advancing from contrary points 

 towards the same spot, not unfrequently isolate pieces of 

 dentine. If a setion be taken through the substance of a 

 tooth, so as to cut the wasting part at a right angle, we shall 

 find the surface acted upon to have an irregular festooned 

 outline, so characteristic, that when once seen it cannot fail to 

 be again recognised. 



VOL. IV. u 



