A system of dental surgery / by Sir John Tomes.

  • John Tomes
Date:
1887
Catalogue details

Licence: Public Domain Mark

Credit: A system of dental surgery / by Sir John Tomes. Source: Wellcome Collection.

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    of the genio-hyoid and genio-liyo-glossus, which probably marked the median line of the body, do not correspond with the jiosition of the mental prominence on the outside of the jaw, Avhich latter has ])artaken in the asymmetrical deve- lopment of face which must have existed, and is considerably displaced to the right. A case of arrested development of both sides of the jaw, not shared in an equal degree by tlie alveolar borders, is related by Professor Humphery. (') The chin was in a plane two inches behind the edge of the upper alveolar edge, but the alveolar border of the lower jaw took a wider sweep than the body of the bone, which it consequcnth^ overlapped. The teeth were as large as in a m'ell-formed jaw, so that thej^ were forced to spread out in a fan-like manner. The manner in M'hich additions are made to the posterior border of the jaw has been described in connection with the growth of tlie jaws of very young subjects. During the period of youth the process is continued, and as the subject approaches manhood, the angle becomes fully pronounced. At the same time, the mental prominence and the points for the insertion of nuiscles attain their permanent characters. In each case the increased size is produced by sub-j^eriosteal development njDon the pre-existing bone. The development of the jaw may, in some respects, be compared to modelling. Portions of new tissue are laid uj)on that already formed, and reduced to the fitting size and sha])C, and again renewed at such jjoints as the attainment of the ultimate form of the part may require. Still, even during manhood, the maintenance of the ftirni of the jaw is dependent to a great extent upon tiie teeth. When the organs of mastication are lost, the Avholc of the alveolar ])rocesses are by degrees removed, the process of absor])tinn being arrested only at those ])oints wliere nuiscles are inserted; neitlier is the waste limited to the alveolar margii\. Both the outer and inner sui'faces of the bone arc (') Mcdico-Chirurgical Review, vol. xxvii., 1S62.
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