The Effect of Orthognathic Surgery on Temporomandibular Joint Function and Symptoms: What are the Risk Factors? A Longitudinal Analysis of 375 Patients

Abstract

The effects of orthognathic surgery (OGS) on the temporomandibular joint (TMJ) are still controversial. Based on a high-volume uniform collective, the function and clinical symptoms of the TMJ and the dysfunction index (Di) by Helkimo were evaluated prior and up to 2years after OGS. A longitudinal cohort study was performed between 2006 and 2016. A comprehensive examination focusing on TMJ function, temporomandibular disorder (TMD) symptoms, and the Di had been performed preopertaively (T0) and postoperatively at 6weeks (T1), 6months (T2), 1 year (T3), and 2years (T4). The predictor variables used were sex, age, skeletal class, type of surgery, and amount of dysfunction or number of TMD complaints before treatment. The outcome of this study was TMD symptoms and the Di. Descriptive and bivariate statistics were computed, and the significance level was set at P<.05. The sample consisted of 375 patients (247 women, 128 men, mean age 28.1±9.4years), 269 with skeletal Class II (71.7%) and 106 with skeletal Class III (28.3%) treated with sagittal split osteotomy bilateral sagittal split osteotomy (n=173) or Le Fort I and bilateral sagittal split osteotomy (n=202). Severe signs of dysfunction (Di 2/3) were seen in 5.9% of the patients before OGS and in 2.1% of the patients 2years after OGS. The difference in Di (Di0/1 and Di2/3) between T0 and T1/T2 was statistically significant (P=.028; P=.011, respectively). TMD symptoms were significantly reduced 2years after OGS (P=.028). Female gender (P=.013), skeletal Class II (P<.001), and counterclockwise rotation (P<.001) were the only risk factors significantly associated with the occurrence of TMD at T1. The results of this study suggest that in most cases TMD symptoms can be significantly reduced and only a few can be induced with OGS. No risk factors were found for long-term effects on the TMJ.