A manual of dental anatomy, human and comparative / by Charles S. Tomes ; edited by H.W. Marett Tims and A. Hopewell-Smith.

  • Tomes, Charles S. (Charles Sissmore), Sir, 1846-1928.
Date:
1914
Catalogue details

Licence: In copyright

Credit: A manual of dental anatomy, human and comparative / by Charles S. Tomes ; edited by H.W. Marett Tims and A. Hopewell-Smith. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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    In many fish, the teeth in some cases more specialised than those of the shark, are scattered over almost every one of the numerous bones which form part of the walls of the mouth and pharynx. In .the amphibia the teeth are more restricted in position, being found only upon the jaws and in connection with the vomers. In reptiles they are even more restricted, whilst in mammals they are absolutely confined to the premaxillary, maxillary, and mandibular bones. In fish and reptiles it is the exception for the teeth in different parts of the mouth to differ markedly from each other; in mammals it is the rule. Most teeth owe their hardness to an impregnation with salts of lime; the organic matrix may, however, be of proteoid substance, keratin, in which case the tooth is of horny consistence, and is spoken of as cornified; or the matrix may be, like that of bone, gelatigenous (that is to say, not gela- tine, but collagen, the anhydride of gelatine which passes into gelatine after prolonged boiling), in which case the tooth is more richly impregnated with salts, and is spoken of as calcified. Horny teeth, so far as they have been investigated, consist of aggregations of cells of the stratum corneum of the oral epithelium, and they are penetrated on their under side by the papillse, whose enormously exaggerated epithelial coats have built them up. The great mass of a calcified tooth is usually made up of dentine, which gives to it its characteristic form, and often practically constitutes the whole tooth. To this may or may not be added enamel and cementum. The simplest teeth are hollow cones, and have no roots; they are calcifications of papillae, and, as has already been mentioned, are sometimes practically identical in structure and form with similar spines upon the skin. As these simple teeth are generally very numerous, it has occurred to some morphologists that multicuspid teeth have originated by the coalescence of several simple cones, each cusp thus being the representative of an original separate tootb. But there is a good deal to be said against the accept- ance of such a view ; the question can, however, be better discussed at a subsequent page. It will suffice to say here that it is much more probable that additional cusps arise by some process of evolution.