Mandibular advancement means lower facial enlargement: a two-dimensional and three-dimensional analysis

Publication date: Available online 16 August 2018

Source: Journal of Oral and Maxillofacial Surgery

Author(s): Nicolas Sigaux, Ali Mojallal, Pierre Breton, Joris Giai, Aurélien Louvrier, Pierre Bouletreau

Abstract

Introduction

Bilateral sagittal split osteotomy (BSSO) is frequently deployed to treat class II malocclusion for both functional and esthetic purposes with expected changes on the profile. The goal of this study was to assess transversal changes in mandibular advancement by comparing 3D (three-dimensional) photogrammetric modifications and 2D (two-dimensional) radiographic enlargement.

Materials and methods

A cohort study was conducted on patients who underwent an isolated advancement BSSO (Obwegeser-Dal Pont II type) for a class II malocclusion. All patients had 3D photogrammetric and 2D radiographic evaluations before and after surgery. Frontal cephalogram radiographs were used to measure the evolution of bigonial distance (BGD) and 3D photographs to measure the evolution of cutaneous bigonial distance (CBGD).

Results

Fourteen patients were included. Mean mandibular advancement was 6 mm. Both BGD (+6.1 mm; p<10-3) and CBGD (+4.2 mm; p=0.0017) were significantly increased. The mean ratio of soft tissue response to transversal skeletal changes was 0.81.

Discussion

This 2D and 3D analysis of transversal modifications shows that advancement BSSO is responsible for significant lower third facial enlargement. This parameter must be taken into account during the preoperative aesthetic assessment, to ensure the provision of pertinent information to the patient and the consideration of complementary surgical correction.

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