3IO PATHOLOGICAL CONDITIONS OF THE TEETH, [sect. 142. 



of the teeth is also tolerably fine, especially upon the masticating 

 surface, where minute foreign bodies, as hairs or grains of sand, 

 are distinguishable when the masticating surfaces are rubbed upon 

 one another; and its intensity is, at any rate, exceedingly great in 

 disease, which is sufficiently explained by the large supply of 

 nerves in the pulp, and the facility with which they may be com- 

 pressed within their hard enclosure. 



In old age, the teeth become denser, the cavity of the pulp gets 

 filled with a kind of irregular dentine, and even completely obli- 

 terated, which, perhaps, is the cause of the natural falling out of 

 the teeth. Iu certain cases, according to Tomes, the fangs are 

 found, in old age, transparent, like horn. 



Respecting the pathological conditions of the teeth, the following facts may 

 be noticed. In exceptional cases, after the falling out of the permanent teeth, 

 their place may be supplied by a third dentition ; but milk-teeth not unfre- 

 quently remain persistent beyond the usual period, and we must be on our 

 guard against taking a retarded second tooth for one of a third set. Extracted 

 teeth can sometimes be re-implanted with success (in fifteen months, an ex- 

 tracted canine tooth of the upper jaw was again completely fastened). Teeth 

 occur as an abnormal formation, especially in the ovaries, but also in other parts. 

 Fractures of the teeth, if they take place within the alveoli, may heal by means 

 of imperfect dentine or cement ; but a regeneration of worn-off parts is met 

 with only in animals (rodentia, e.g.), in which the teeth grow continually. 

 Hypertrophy of the cement, so-called exostosis, also dental formations upon 

 the walls of the pulp-cavity and ossification of the pulp itself, are extremely 

 frequent, and are the consequences of chronic inflammations of the periosteum 

 of the pulp. A partial disappearance of the- root is likewise not unfrequent. 

 Necrosis of the teeth takes place when the periosteum is detached from the 

 tooth, or when the pulp itself has perished ; and in this condition the teeth 

 become rough and dark, or black, and fall out. The true nature, as well as 

 the cause of caries of the teeth, is doubtful. It attacks false as well as living 

 teeth (Tomes), and always commences externally and from the enamel- 

 membrane (Ficinus) ; whence a very essential share in its production has 

 been ascribed to the fluids of the mouth. By this, however, it is not meant 

 to assert, that in living teeth there may not be a greater predisposition to 

 caries in some than in others, possibly because some peculiarity in their che- 

 mical composition or mode of nutrition renders them less capable of resist- 

 ance. At any rate, caries is not merely a solution of the teeth by the fluids 

 of the mouth, for a putrefactive decomposition of the organic parts of the 

 tooth, which is accompanied by the development of infusoria and fungi, goes 

 on at the same time ; nay, the latter, according to the statements of Ficinus, 

 appear to play the chief part in this process, inasmuch as caries proceeds 

 principally from those parts of the tooth where the organisms in question 

 may grow undisturbed, as the fissures and small pits in the enamel, the de- 

 pressions on the crowns of the molars, and the crevices between the teeth ; 

 but not in other places where the dentine may have been exposed, as iqjon 

 the masticating surface, on filed parts, etc. In caries, the discoloured enamel- 



