Intraoperative condylar positioning techniques on mandible in orthognathic surgery

The surgical condylar displacement often resulted in relapse and serious symptoms of temporomandibular joint disorders (TMD) after orthognathic surgery. To minimize the displacement, numerous techniques have been proposed. To verify their accuracy in positioning and effectiveness in preventing post-operative TMD and relapse, we reviewed the literature related to intraoperative condylar positioning techniques on the mandible in this study.The literature on condylar positioning techniques was reviewed with two charts, including the non-computer-assisted and the computer-assisted positioning methods. The pre- and post-operative alterations of condyles, the post-operative temporomandibular joint (TMJ) function and surgical relapse were analysed regarding the techniques. The clinical usage and characteristics were reviewed as well.A total of 22 articles, including 907 patients, have been reported since 2001. Nearly all methods reach a considerable positioning accuracy within the range of 1-2 mm and 1-2° from the pre-operative position. We ranked the accuracy of the methods from high to low: CAD/CAM CPDs > CAD/CAM titanium plate positioning > manual positioning > computer-assisted navigation systems > imaging positioning systems. Most skeletal class II and class III patients achieved great occlusion and had no TMJ dysfunction or relapse after condylar positioning.Both the non-computer-assisted and computer-assisted condylar positioning techniques reach considerable accuracy in locating the pre-operative condyle position and preventing TMJ dysfunction and surgical relapse. Different levels of surgeons and cases can benefit from multiple suggested positioning methods. Further research with large samples and long-term follow-up is worth looking forward to upgrading the current methods, improving the clinical utility and developing new positioning techniques.