The human mandible in lateral view: elliptical fourier descriptors of the outline and their morphological analysis.

摘要

An original procedure based on new developments in elliptical Fourier methods associated with image analysis technics was applied to 117 human mandibles in lateral view (69 males, 48 females) in order to analyze interindividual variability and sexual dimorphism. Original parameters, called elliptical Fourier descriptors, allowed for the quantification of the shape of an outline irrespective of its morphological complexity, and provided a precise individual characterization. The use of step by step reconstructions with an increasing number of harmonics allowed for demonstration of the morphological contributions of the elliptical Fourier descriptors, and relationships to precise anatomical features were established. The first harmonics (1st to 8th) described the general mandibular shape, and the later harmonics (8th to 14th) characterized accessory and finer morphological features. The proportion of individuals presenting significant sexual dimorphism was 97.1% in males and 91.7% in females, and after size normalization 84.1% in males and 81.2% in females. Even after removal of the size component, these results in regard to mandibular dimorphism remained better than those found by classical approaches; this could be due to the use of elliptical Fourier analysis which takes into account all the information of the mandibular outline. Compared to the size component, the shape component seemed to be more important in the sexual dimorphism of the human mandible than previously recognized. The present approach opens interesting anthropological and clinical perspectives for the characterization of mandibular morphology.