Anatomy and histology of the mouth and teeth by Broomell Isaac Norman 1858-1941 & Fischelis Philipp b. 1857

Author:Broomell, Isaac Norman, 1858-1941 & Fischelis, Philipp, b. 1857
Language: eng
Format: epub
Tags: Mouth, Tooth
Publisher: Philadelphia : P. Blakiston's son & co.
Published: 1913-03-25T05:00:00+00:00

does not indicate the period at which the degeneracy of the tooth begins, for, in a year or two after the root is completely formed and the apical foramen established, decalcification begins at the apical extremity and continues in the direction of the crown until absorption of the entire root has taken place and the crown is lost from lack of support. Decalcification in the incisors begins between the fourth and fifth years, in the molars from the seventh to the eighth years, and in the cuspids about the ninth year.

The deciduous teeth are twenty in number, ten in each jaw, and may be classified as follows: Four incisors, two cuspids, and four molars. The incisors, central and lateral, occupy the central portion of the arch, are placed two upon each side of the median line, and are succeeded by the four permanent incisors, which finally occupy the same position. The cuspids are located immediately to the distal of the lateral incisors, and are displaced by the permanent cuspids. The first and second molars come next in the arch, but, unlike the anterior teeth, are followed by permanent successors of another class, the first and second bicuspids, the permanent molars erupting posteriorly to these as the jaw increases in length.

In general the deciduous teeth resemble their permanent successors, yet there are a number of minor differences which will require a comparative description. Both the crowns and the roots are much smaller in every direction than those of the permanent teeth, but the diameter of the crowns is proportionately greater than that of the roots, while the roots are proportionately longer. The fact that the roots are smaller in proportion than the crowns is productive of a neck much more constricted. The roots of the deciduous teeth are the same in number as those of the corresponding permanent teeth, the incisors and cuspids being provided with one, the upper molars with three, and the lower molars with two.

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