Post-operative soft tissue changes in patients with mandibular prognathism after bimaxillary surgery

Abstract

The objective of this study was to evaluate the three-dimensional soft tissue changes observed over time after bimaxillary surgery for mandibular prognathism using cone-beam computed tomography (CBCT) superimposed imaging. CBCT scans were obtained for 25 patients before bimaxillary surgery (T0), at 2 months after surgery (T1) and at 6 months after surgery (T2). Cephalometric variables from the reoriented volumetric images were measured and compared at T0, T1, and T2. The quantitative surface displacement in the middle and the lower third of the facial soft tissue using CMF tools was assessed by superimposing the T0 and T1 or T0 and T2 3D images. The soft tissue in middle third of face moved forward at T1 and significantly moved backward from T1 to T2 (Ch-Al, p < 0.001; Al, p < 0.05; Pn, p < 0.05). Most of the soft tissue changes from T1 to T2 were not correlated with the hard tissue changes (p > 0.05), while the cheeks were positively correlated with the soft tissue around them (Exo-Al, p < 0.01; Ch-Al, p < 0.01). Post-operative soft tissue changes occurred in the middle third of the face and are considered to be more complex than the changes in the lower third of face. Therefore, soft tissue assessment at least 6 months after surgery is desirable.