Journal of Dental Research, Vol 69, 1298-1306, Copyright © 1990 by International & American Associations for Dental Research Online Journals
Transverse development of the human jaws between the ages of 8.5 and 15.5 years, studied longitudinally with use of implants
E. L. Korn and S. Baumrind
Biometric Research Branch, National Cancer Institute, Bethesda, Maryland 20892.
We report longitudinal data on the transverse widening of the maxilla and
mandible from a sample of normal subjects (11 males and 20 females) with
metallic implants of the Bjork type. Data were from measurements on lateral
and frontal (posterior-anterior) cephalograms generated at annual intervals
between the ages of 8.5 and 15.5 years (although data were not available
for all subjects at all time points). The maxillary data were, in general,
similar to those reported by Bjork and Skieller (1974, 1977) for a smaller
sample of slightly younger boys. During the age interval studied,
transverse widening was greater in the more posterior part of the palate.
[The mean annual rate of change in the posterior-most (zygomatic) region
was 0.43 mm, sd = 0.18 mm; p less than 0.001.] Although the rate of palatal
widening was not large in absolute terms, widening appeared to continue
throughout the age interval under study, and there was no evidence to
support the conventionally accepted idea that palatal growth in the
transverse dimension tapers off substantially or even ceases during the age
interval under observation. Evidence of statistically significant widening
of the mandibular arch by means of transverse rotation of the osseous
matrix was noted in nine of the 29 subjects for whom three-dimensional
mandibular information was available. For these nine subjects, the
estimated annual increase in mandibular arch angle ranged from 0.52 degrees
to 1.40 degrees. As far as we are aware, this is the first report of
mandibular matrix rotation in the transverse direction from a sample of
subjects with metallic implants. The finding that spontaneous changes in
this dimension are relatively common raises the possibility that classical
attitudes concerning the immutability of osseous relationships in the
symphyseal region during growth may be inappropriate.
