Page 245 - My FlipBook

PREDISPOSING CAUSES OF DENTAL CARIES. 217

3. In the third phiee, fissures or cracks in the enamel are
regarded as a predisposing cause. I have not, however, been
able to convince myself that decay frequently starts from these
enamel-cracks, often found in senile teeth. They are usually
too narrow to permit the entrance of food-particles, and conse-
quently do not serve as points of retention.
4. In the fourth place, teeth are predisposed to decay by a
crowded, irregular position. An instructive example is furnisiied
in cases where the first bicuspid stands inside of the arch, so as
to form a triangle with the second bicuspid and the cuspid ; or
the second bicuspid forms a triangle with the first bicuspid and
first molar. It is impossible to keep the space between these
three teeth clean, and fermentation and acid formation continu-
ally occur there and attack the teeth. Xot only in such cases,
but wherever a crowded position of the teeth favors the reten-
tion of food-particles, or renders their removal diflieult, a pre-
disposition to caries prevails. The form of a tooth is not without
influence ; teeth with convex approximal surfaces touching each
other at one point only (Fig. 104) are, ccEteris paribus, less subject
Fig 104. Fin. lOJ.

to caries than teeth with flat or slightly concave surfaces (Fig.
105), because the latter cannot be kept so clean, either sponta-
neously (by the tongue, etc.) or with the brush.
5.. A recession or loosening of the gums from the neck of the
tooth not only lays bare the dentine, but also permits the entrance
of food-particles between the necks of the teeth or into the
pockets formed by the loosening of the gums, by which means a
further predisposing cause for caries is furnished.
6. Many consider pregnancy as a predisposing cause. It is not
to be denied that during pregnancy women are particularly sul)-
jeet to caries. The reason for this is, however, probably to be
sought in the fact that the patients generally neglect the care
of the mouth during that time, and that the buccal secretions