Evaluation of soft tissue changes in the submandibular region after orthognathic surgery

Objective: The aim of the study is to evaluate the changes in the submandibular soft tissues after mandibular advancement or setback with orthognathic surgery by cephalometric radiographic analysis. Subject and Method: A total of 74 individuals who had the mandible advancement or setback with orthognathic surgery were included in the study. While 42 of them were Class 3 (MS) patients with setback of the mandible, 32 had Class 2 (MA) malocclusion. Linear, angular measurements and area measurements were analyzed on lateral cephalometric radiographs taken before orthognathic surgery and at least 6 months after the operation. Analyzes were measured on the Dolphin Imaging Software program. Intra-group pre- and post-operative (T1-T0) differences were evaluated using independent t- test statistical analysis. The relationship between the changes in skeletal mandibular cephalometric parameters and submandibular soft tissues was evaluated for both groups by performing Pearson correlation analysis. In addition, whether there was a difference in submandibular soft tissue changes between MS and MA group was examined with the independent sample T test. Results: Submandibuler length (C-Me') decreased after the mandibular setback in Group MS, cervicofacial angle increased, soft tissue thickness (Me-Me') increased at Menton, statistically significant in Areas 1, 4 and 5 (p<0.05) decrease was observed. Cervicofacial angle decreased in Group MA, the angles of the submandibular length (CMe') with horizontal planes (HR and MP) decreased, and it was observed that it increased in Area 1. There was a significant post-surgical difference in CMe' length, throat length, lip-chin-throat angle, cervicofacial angle and Area 4 parameters between Groups MS and MA (p<0.05). There was a correlation between sagittal movement of Pog and Me points (Pog-VR and Me-VR) and Throat length, lip-chin-throat angles in both groups. When the relationship between mandibular and vertical direction parameters and area measurements was evaluated, it was found that Area 2 in Group MS and Area 3 in Group MA showed moderate negative correlation. Conclusion: After orthognathic surgery, the relationship of the mandible with its associated soft tissues can be affected by many factors. Although there are significant changes in the submandibular region in both types of surgical movement, their prediction is quite difficult. Contrary to expectations, despite the backward movement of the mandible, a decrease was observed in area measurements in this region, while an increase was observed in the forward movement of the mandible. Keywords: Submandibular soft tissue, Mandibular setback, mandibular advancement, Orthognathic surgery, Skeletal Class 3 anomaly, Skeletal Class 2 anomaly