Soft Tissue Changes After Clockwise Rotation of Maxillo-Mandibular Complex in Class III Patients: Three-Dimensional Stereophotogrammetric Evaluation

Abstract

Objectives: To evaluate the linear, angular, and volumetric changes of soft tissue after clockwise repositioning of the maxillo-mandibular complex in skeletal class III patients using three-dimensional (3D) stereophotogrammetry and to determine the correlation between changes in the skeletal and soft tissue variables. Methods: This study included 18 skeletal class III patients who underwent two-jaw surgery; superior impaction and clockwise rotational movement of the maxilla with the rotation center at upper incisors, and setback of the mandible. Lateral cephalograms and 3D photographs taken before and 6 months after surgery were compared. Results: After maxillary impaction of anteriorly 1.7 mm and posteriorly 3.1 mm, and mandibular setback of 8.7 mm, the volume of lower lip and chin region decreased significantly by 33.6 cm(3) (13% net change, P < 0.001), while paranasal and upper lip region volume increased by 3.2 cm(3) (2%) and 7.2 cm(3) (4%), respectively. Conclusion: The clockwise rotation of maxillo-mandibular complex in class III patients significantly reduced lower lip and chin volume with minimal increase in paranasal and upper lip volumes. 3D stereophotogrammetry can provide quantitative evaluation of facial soft tissue volumetric changes.