Relationship between bilateral condylar bone change and mandibular morphology: a study using morphometry.
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.
D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016018:Least-Squares Analysis; D008311:Malocclusion, Angle Class I / Q000473:pathology; D008312:Malocclusion, Angle Class II / Q000473:pathology; D008334:Mandible / Q000473:pathology*; D008335:Mandibular Condyle / Q000473:pathology*; D008336:Mandibular Diseases / Q000473:pathology*; D015999:Multivariate Analysis; D011862:Radiography, Panoramic; D018709:Statistics, Nonparametric; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed