Does Mandibular Advancement Orthognathic Surgery Lead to TMJ Dysfunction in Skeletal Class 2 Patients? A Quasi-Experimental Trial in an Iranian Population

BACKGROUND: We aimed to evaluate the possibility of temporomandibular joint (TMJ) dysfunction following mandibular advancement surgery in skeletal class 2 patients. METHODS: All healthy non-syndromic patients with Class 2 deformity, who were eligible for mandibular advancement surgery, were included in this before-after quasi-experimental study. The main intervention was mandibular advancement through bilateral sagittal split osteotomy (BSSO). Maxillary impaction or setback surgery using LeFort 1 osteotomy was simultaneously performed in some cases. Variables such as TMJ pain, clicking, crepitus, or any other type of sounds or complaint as well as the amount of maximum mouth opening (MMO) were evaluated before surgery and two months postoperatively. RESULTS: Thirty patients including 15 men and 15 women with a mean age of 23.3 ±2.7 yr were studied. The mean amount of mandibular advancement displacement was 3.30 ± 0.87 mm. The rate of TMJ dysfunctions and complaints was relatively low two months postoperatively when compared to the preoperative state. Postoperative evaluation demonstrated that there was no significant correlation between the presence of TMJ symptoms and dysfunctions and the type of surgery. After treatment was completed, the mean MMO reduced significantly from 39.03±5.86 to 38.12±6.05 (P<0.001). CONCLUSION: Mandibular advancement with BSSO surgery in skeletal class 2 patients did not clinically lead to TMJ dysfunctions. Among all the investigated factors, only preoperative pain, noises, or complaints were proven to have predictive value for postoperative TMJ dysfunction.