Journal of Dental Research, Vol 69, 1834-1838, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Long-term effects of orthodontic forces on the morphology of the rat-incisor socket and its location in the mandible
I. Brin, Y. Michaeli and S. Steigman
Department of Orthodontics, Hebrew University Dental School, Jerusalem, Israel.
The effect of orthodontic force application on the rat-incisor socket and
mandible was studied on roentgenograms. A mean linguo-intrusive force of 19
+/- 0.6 g was applied continuously to the shortened left lower incisor for
a period of two (group A) and four weeks (group B). A third group of rats,
subjected to shortening of the left mandibular incisor only, served as a
hypofunctional control (group C). A fourth group of normal rats constituted
the intact control (group D). After a recovery period of three months, the
animals were killed, and standardized roentgenograms of the cleaned
mandibles were taken. Socket and mandibular dimensions were measured on
magnified tracings of the roentgenograms. Comparison of groups A and B with
the control groups, on the one hand, and of group C with group D, on the
other, facilitated isolation of the hypofunctional factor. In groups A and
B, the orthodontic forces caused changes in the parameters affected (i.e.,
socket area, alveolar bone thickness, mandibular dimensions) and not
affected by hypofunction (i.e., socket angulation and location,
anterior-socket length). The former findings implies modification of the
adaptive capability of dental structures to functional demands. It is
concluded that mechanical loading of the incisor for two to four weeks
causes long-lasting changes in the socket and its surrounding bone.
