Three-dimensional long-term assessment of soft tissue stability after orthognathic mandibular advancement for class II malocclusion correction.

Abstract

Objectives: This study aims to assess the stability of soft tissues one and three years after orthognathic mandibular advancement surgery by superimposing the cone-beam computed tomography (CBCT) images and quantifying potential soft tissue changes following surgery.

Materials and methods: In this prospective observational study, changes in the hard and soft tissues of the chin, lower incisors, and lower lip due to displacement and/or bone remodeling were analyzed using three-dimensional models based on CBCT superimposition images acquired before surgery (T0), one year after surgery (T1), and three years after surgery (T3). The cranial base was used as a reference for the superimpositions, which were based on fully automated grayscale voxel-wise registrations.

Results: The soft chin showed more than 2 mm displacement between T0 and T1 and between T0 and T3, along with hard chin displacement. The lower lip had less displacement at T0 and T1. The soft tissue adaptation between T1 and T3 indicates stability of the soft tissue correction.

Conclusion: Even though the soft tissue three-dimensional response one year after surgery was variable, the investigated anatomical regions were stable between one- and three years post-surgery, and only the soft chin exhibited some relapse. The soft tissue chin changes observed were strongly correlated with the hard chin.

Clinical relevance: This study provides comprehensive and long-term insights considering soft tissue facial features' stability after orthognathic surgery, impacting orthodontic treatment planning, and integrating both problem-oriented and goal-oriented approaches. The outcomes emphasize the importance of surgical aesthetics alongside occlusion, ultimately contributing to better long-term results and enhanced patient satisfaction.