Mandibular shape prediction using cephalometric analysis: applications in craniofacial analysis, forensic anthropology and archaeological reconstruction

Ahmed Omran,Kathryn Smith,Farhad B Naini,Ching Yiu Jessica Liu,David Wertheim

doi:10.1186/s40902-020-00282-3

Abstract

BackgroundThe human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion.ObjectivesThe objectives of this study were to determine whether the Sassouni cephalometric analysis could help predict two-dimensional mandibular shape in humans using cephalometric planes and landmarks.Materials and methodsA retrospective computerised analysis of 100 lateral cephalometric radiographs taken at Kingston Hospital Orthodontic Department was carried out.ResultsResults showed that the Euclidean straight-line mean difference between the estimated position of gonion and traced position of gonion was 7.89 mm and the Euclidean straight-line mean difference between the estimated position of pogonion and the traced position of pogonion was 11.15 mm. The length of the anterior cranial base as measured by sella-nasion was positively correlated with the length of the mandibular body gonion-menton, r = 0.381 and regression analysis showed the length of the anterior cranial base sella-nasion could be predictive of the length of the mandibular body gonion-menton by the equation 22.65 + 0.5426x, where x = length of the anterior cranial base (SN). There was a significant association with convex shaped palates and oblique shaped mandibles, p = 0.0004.ConclusionsThe method described in this study can be used to help estimate the position of cephalometric points gonion and pogonion and thereby sagittal mandibular length. This method is more accurate in skeletal class I cases and therefore has potential applications in craniofacial anthropology and the ‘missing mandible’ problem in forensic and archaeological reconstruction.

Highlights

The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion
Bland-Altman plots performed using a macro in Minitab v19 were used to measure mean differences and show upper and lower limits of agreements between the traced positions of Go (Figs. 2 and 3) and Pog (Figs. 3 and 4) when compared to the positions estimated by Sassouni+ analysis (Fig. 5)
The novel method described in this study can potentially be used in conjunction with a lateral cephalometric radiograph to provide information that would be of use in predicting the two-dimensional shape of the human mandible

Summary

Introduction

The human mandible is variable in shape, size and position and any deviation from normal can affect the facial appearance and dental occlusion. The shape, size and the relationship of the mandible to the maxilla and cranial base is of primary interest as it can influence the position and appearance of the facial soft tissues as viewed in profile. As the mandibular dentition is contained in the alveolar process of the mandible, any deviation in the shape, size or relationship of the mandible to the maxilla may be an aetiological factor in a presenting malocclusion [1]. In orthodontics and craniofacial reconstructive surgery, the shape, size and relationship of the mandible to the maxilla and cranial base is first assessed clinically and this may be supplemented by requesting a lateral cephalometric radiograph (LCR) in the natural head position [3]

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Discussion

Conclusion