Three-dimensional evaluation of dental adaptation and skeletal stability following posterior open-contact surgical occlusion

Abstract

This study evaluated the effects of different surgical occlusion designs, particularly posterior open contacts, on dental movement, skeletal stability, and occlusal outcomes in orthognathic surgery. A total of 49 skeletal Class III patients were classified into tripod contact (TRI) and non-tripod contact (NTR) groups based on molar contact conditions. Cone-beam computed tomography and T-scan analyses were performed at preoperative, 1-week postoperative, and post-treatment stages. Skeletal and dental changes were assessed using three-dimensional superimposition. Both groups showed significant improvement in skeletal relationships and occlusal parameters, with mild mandibular upward relapse. In the NTR group, the average maximum posterior interocclusal distance measured preoperatively was 3.84 mm and demonstrated significantly greater lower molar extrusion (1.28 mm, p  < 0.05). Maxillary incisor intrusion was positively correlated with mandibular forward relapse ( r  = 0.493, p  < 0.05). No significant differences were found in final occlusal outcomes between groups. These findings suggest that stable outcomes can be achieved even without posterior molar contact, provided adequate anterior occlusal support is established, offering clinical guidance for surgical setup and postoperative orthodontic strategies.