Investigation of relapse in class iii orthognathic surgery patients by surface electromography and motion analysis method

ABSTRACT Objective: The aim of this study is to investigate the relationship between stability of orthognathic surgery and activation of the masticatory muscles; to evaluate the masticatory muscle activity between patients with skeletal Class III anomalies and skeletal Class I anomalies by sEMG and kinematic analysis. Method: Our study consisted of 56 individuals; each group consisted of 28 patients. The mean age of patients in the surgery group was 20±4,1 years, while 18,32±1,3 years in the control group. Lateral cephalograms were taken before surgery, at the end of treatment, and at least two years after orthognathic surgery, at the orthognathic surgery group. Lateral cephalometric recordings were also taken from the control group. sEMG activity of the masseter, temporal, suprahyoid and mental muscles and kinematic movements of the mandible were examined in both groups. Firedman, Mann Whitney-U tests performed. Results: Lateral cephalometric records at different periods were examined in orthognathic surgery group were not found to be statistically significant. sEMG data of the groups were examined; activations in masseter, temporal, mental and suprahyoid muscles were higher in the control group. Kinematic data were examined and found that deviation values during mouth opening and closing did not differ in X° plane and in Y(mm) plane. It was observed that the differences in Y° plane were lower in the control group; the X(mm), Z° and Z(mm) differences were lower in the surgery group. Conclusion: Cephalometric analysis showed no relapse in the surgery group. Muscular activity was found to be lower in the surgery group; associated with the origin of the dentofacial deformity and the stability after treatment. Deviations of kinematic data in the control group were found higher, showing that dentofacial anomalies and asymmetries were treated, neuromuscular balance were obtained. Key words: Skeletal Class 3 anomalies, orthognathic surgery, relapse, sEMG, kinematic analysis