Evaluation of sex dimorphism of the mandible with geometric morphometric analysis: conventional and reconstructed panoramic radiography study

Abstract

Purpose: The purpose of the study was to investigate the mandible shape dimorphism between males and females both on conventional panoramic radiographs (cPR) and reconstructed panoramic radiographs obtained from cone beam computed tomography (rPR) with geometric morphometric method.

Methods: Panoramic radiographs and cone beam computed tomography scans were performed on 33 males and 35 females with median age 23.0 (13.0-57.0) years old. The mandibular shape comparisons between genders were examined with Procrustes analysis, mandible shape classification analysis was made with principal component analysis and shape deformations were concluded from thin plate spline (TPS) analysis.

Results: Age had no statistically significant difference between gender (p = 0.580). For the shape of mandible on cPR and rPR, there were statistically significant differences between males and females (p = 0.002, p = 0.032, respectively). The shape variabilities of mandible on cPR for females were 0.054 and for males 0.053. The shape variabilities of mandible on rPR for females were 0.051 and for males 0.049. Both on cPR and rPR, the shape variability of the females' mandible was similar within their group, the shape variability of the males' mandible was similar within their group. In the examination of mandibular dimorphism in cPR, maximal deformations were seen in the region between the mandibular notch, posterior ramus, anterior ramus, gonion, in both sides, in TPS graphs. On the other hand, a high level of deformations was observed in all landmarks that define the mandibular shape on rPR.

Conclusions: The mandible dimorphism can be detected in the examination performed with geometric morphometric methods on cPR and rPR. While mandible shape differences according to gender are seen most in the ramus region in cPR, differences can be detected in all landmarks in rRP.

Keywords: Cone beam computed tomography; Forensic anthropology; Geometric morphometrics; Mandible shape; Panoramic radiography; Sexual dimorphism.