Comparison of symphysis morphology in normodivergent patients of short and normal mandible

Abstract

Introduction: Mandibular Symphysis (MS) is one of the most important regions of craniofacial complex. Understanding its morphology is important both for differential diagnosis and orthodontic treatment planning. Hence the purpose of this study was to measure symphysis morphological traits of patients with deficient mandibles versus that of normal mandible patients.

Material and Methods: It was a cross-sectional study that was carried out in Out Patient’s Department of Margalla Institute of Health Sciences. The duration of this study was six months from June 2015 to January 2016. Thirty four normal angle patients with MMA in the range of 25.5° ± 5.3° were included in the study. McNamara analysis was done to divide them into two groups, first group of patients with short mandible and the second group of patients with normal mandible. On cephalogram, angle B-Pog-Me, angle B-B₁-Gn and perpendicular distance from Pog to B-Me line were measured for all patients. The readings were compared for the two groups of patients.

Results: The angle B-B₁-Gn (symphysis vertical dimension) and anterior prominence of MS (perpendicular distance between Pogonion and B-Me line) showed no significant differences between the two groups (P>0.05). The angle B-Pog-Me (symphysis convexity) was found to be greater in short mandible group of patients. This parameter showed statistically significant difference between the two groups (P<0.05).

Conclusions: Patients with short mandible have different symphyseal morphology than patients with normal mandible. Anterior prominence of symphysis and its vertical dimensions are increased in long mandible patients. But symphyseal convexity is increased in short mandible patients showing statistically significant difference between the two groups.