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.

    86/808 page 70
    may find sections showing in one part dentine which has been Init recentlj^ formed ; in another part, absorption in active progress; and in a third, the deposition of bone on the snrface of the wasted dentine. In no instance, however, is dentine deposited npon the surface of that wliich has been diminished by absorption. It would appear that tlie dentinal pulp, although its func- tion may be changed into that of absorption, or its place be taken by an absorbent organ, and this, again, changed to one for the development of bone, is incapable of resuming under any recognised circiunstances its primary function of dentinal development. In other words, that a portion of dentine when removed by absorption, cannot be replaced : while in bone, or cementum, the renewal of a lost portion is of frequent occurrence. It w ill be seen that the foregoing facts bear upon the opinions advanced by Messrs. Tomes and De ]\Iorgan in the l)aper on the structure and development of bone, before cited ; that we have indications in teeth, as in bone, of alternations of removal and of deposition of tissue. In the young subject, the development of bone tissue is in excess of absorption, allowing the bones to increase in size; in middle life the two powers, iinder ordinai-y circumstances, balance each other, and the bones preserve their adult dimensions ; while in old age the absorbent action appears to preponderate. Conditions pretty nearly parallel occur in the dental tissues after the temporary tooth has been fuUy formed ; ])oi-tions of cementum are removed, and with them, in some cases, a little dentine ; the lost parts are replaced by cementum, more or less, but the absorption being in excess of the development, the tissues disappear, and the tooth is shed. After the formation of the i)ermanent teeth we have occasional alternations of the two actions; but they are balanced, and neither increase nor diminution in size is observed. But as age comes on, it often happens tliat absorption is in excess, tlic roots diminish in size, the tectli become loose, and fidl out.
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