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This study was undertaken to evaluate the relationship between bilateral
condylar bone change (BCBC) and mandibular morphology.
Thirty Japanese women with BCBC as diagnosed from computed tomographic
scans were compared to 2 control groups: 26 Class I and 25
Class II Japanese women. All cephalograms were traced and scanned,
and 14 homologous landmarks were digitized. Coordinates were used
for cephalometric analysis, Procrustes analysis, Euclidean distance
matrix analysis (EDMA), and thin-plate spline (TPS) analysis. Comparison
of the cephalometric data for the BCBC and Class I groups revealed
significant shrinkage in the condylar process and ramus height,
in addition to a shorter body length. The centroid size showed that
BCBC mean geometric forms were smaller than those of Class I and
Class II. The landmark morphology of the BCBC group differed from
both Class I and Class II, as shown by the residuals (P < .001). EDMA
showed expansion of infradentale-pogonion (9.9%) and along the anterior
slope height of the condyle (28.6%), while the posterior slope
height decreased (21.6%). The vertical ramus height (gonioncondylion)
also decreased by 11.8% in comparison to Class I. Compared
to Class II, BCBC ramus height was shorter by 8.9%, condylar
width decreased 13.7%, and the posterior condylar slope was 22%
shorter. TPS analysis showed increased antegonial notching, a vertically
expanded symphysis, and a collapsed and more horizontal
condyle in the BCBC group. The combination of the above methods
was very helpful in assessing mandibular morphology and showed
that BCBC might be related not only to changes in the condyle, but
may dictate changes in the rest of the mandible as well.
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