Page 696 - My FlipBook

694 ORTHODONTIA AS AN OPERATIVE PROCEDURE.
It is often of the utmost importance to ascertain whether a tooth is
delayed in eruption or is permanently absent. The tooth most likely
to be absent is the third molar. The one next most likely to be absent
is the lateral incisor, generally referred to as the " missing lateral."
In case the permanent laterals do not erupt at the proper time, the
question often arises with a crowded arch, whether to preserve space
for them in hopes of their eruption, or to allow the other teeth to crowd
along and occupy the space. Hitherto it was impossible to answer this
question, but lately science has come to our aid, and by the skiagraph
the uncertainty can be made a certainty.

Fig. 611. Fig. 612.

Figs. 611-614, and the following description by Dr. J. N. :M'Dowell,
'
will illustrate the subject of delayed eruption :

Fio. 61.3. Fig. 614.

"Fig. 611 shows the models of a boy eight years old. The space
for the laterals is entirely closed up. The teeth in both the upper
and lower arches were regulated, making the necessary room for the
laterals in the upper arch (see Fig. 612). This space was retained for
two years, and at the end of that time there was still no sign of the
1 Dr. J. N. M'Dowell, Dental Cosmos, March 1900, vol. xlii. p. 237.