A manual of dental anatomy : human and comparative / by Charles S. Tomes.

Date:
1894
Catalogue details

Licence: Public Domain Mark

Credit: A manual of dental anatomy : human and comparative / by Charles S. Tomes. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    183/614 (page 167)
    The process is exactly like the calcification of atiy mem- l»nvnc bone, and the connective tissue bundles remind one of those which are believed to be the occasion of the ft)rmation of Sharpey's fibres in bone. In the case of teeth which are going to be anchylosed to the subjacent bone, these fibres run continuously from the interior of the dentine cap down to the bone, and calcification in and around them binds the two inseparably together. It is interesting to note, especially in connection with the fact that some observers believe Sharpey's fibres to be elastic, that the hinged teeth of the pike (see Fig. 89) owe their power of resilience entirely to the elasticity of these connective tissue bundles, which do not become completely calcified, although at an eai'ly stage it would be quite im- possible to say whether a particular tooth was going to be anchylosed, or to be a hinged tooth held up to its work by clastic strings. The Calcification of Cementum.—Just as is the case with bones elsewhere in the body, cementum may perhaps be formed in two distinct ways—by membranous ossification, and by ossification in a fibro-cartilage, the former method obtaining upon the roots of teeth, and the latter upon those crowns where the cement organ described by Magitot exists. At the time when the crown of a tooth appears tlu'ough the gum, it alone is complete, and the root has yet to be calcified ; as each portion of dentine of the root is completed, it is coated with a closely adherent vascular membrane which is in fact the follicle wall, and which is to become, when the cement is formed, the alveolo-dental periosteinn. The inner or dentinal face of this membrane presents a layer of large cells, the osteoblasts of (Jegenbaur, and it is hy their calcification that bone or cementum is directly formed. These osteoblasts are themselves a special de- velopment where bone is about to be manufactured, as is clearly explained in the following extract from a paper by