1 Associate professor Dentofacial Deformities Research Center, Research Institute of Dental Sciences and School of Dentistry, Shahid Beheshti University of Medical Sciences

2 Post graduate students, Department of Orthodontics , Shahid Beheshti University of Medical Sciences, Tehran, , Iran

3 PHD in Biostatistics, Associate Professor, Department of Basic Sciences,School of Rehabilitation, Shahid Beheshti University of Medical Sciences,Tehran, Iran



Background and aim: Number of studies evaluating the changes in head position following mandibular setback surgery (MSS) is scarce. This study sought to assess the craniofacial morphology, head and neck posture following mandibular setback surgery.
Materials and methods: This retrospective, longitudinal, semi-experimental study was performed on 35 patients with Class III malocclusion. Radiographs taken at baseline and one year after surgery were retrieved from the medical records of patients. Lateral cephalograms were scanned and landmarks were marked on the first (baseline) radiograph. The second radiograph was superimposed on the first radiograph, true vertical lines or a ruler were considered as parallel images and a line was drawn along the SN from the point S. After superimposition, cephalometric variables were measured using Orthosurger X software (Iran). The mean, standard deviation (SD) and range of changes in each group were calculated. The significance of differences caused by surgery was analyzed using paired t-test.
Results: The total mandibular length, mandibular body length, ramus length, SNB, SN-Pog, A-N-Pog, the angle between the body and ramus and the mandibular plane inclination significantly decreased; while, ANB angle, overjet and overbite significantly increased. No significant change occurred in the head position or cervical vertebra following MSS.
Conclusions: Since changes in the positions of cervical hard tissue were not significant, decreased airway volume following MSS seems to be related to the soft tissue structures namely the tongue, the soft palate and the suprahyoid and cervical muscles.