Morphometric Analysis of the Mandible in Subjects with Class III Malocclusion

• Main Authors: Jin-Yun Pan, Szu-Ting Chou, Hong-Po Chang, Pao-Hsin Liu
• Format: Article
• Language: English
• Published: Wiley 2006-07-01
• Series: Kaohsiung Journal of Medical Sciences
• Subjects: adults; children; Class III malocclusion; mandible; morphometric analysis
• Online Access: http://www.sciencedirect.com/science/article/pii/S1607551X09703195

This study evaluated the deformations that contribute to Class III mandibular configuration, employing geometric morphometric analysis. Lateral cephalograms of male and female groups of 100 young adults and 70 children with Class III malocclusion were compared to those of counterparts with normal occlusion. The sample included an equal number of both genders. The cephalographs were traced, and 12 homologous landmarks were identified and digitized. Average mandibular geometries were generated by means of Procrustes analysis. Thin-plate spline analysis was then applied to mandibular configurations to determine local form differences in male and female groups of adults and children with normal occlusion and Class III malocclusion. The mandibular morphology was significantly different between these two groups of male and female adults, and children (p < 0.0001). This spline analysis revealed an anteroposterior elongation of the mandible along the condylion-gnathion axis, showing an extension in the regions of the mandibular condyle and ramus, and of the anteroinferior portion of the mandibular symphysis in Class III groups. More extension was evident in Class III adults. The deformations in subjects with Class III malocclusion may represent a developmental elongation of the mandible anteroposteriorly, which leads to the appearance of a prognathic mandibular profile.