Orthodontic principles and guidelines for the surgery-first approach to orthognathic surgery.

The surgery-first approach has become a new paradigm in orthognathic surgery. With the surgery-first approach, most of the patient's teeth are in their original positions and have not undergone orthodontic treatment prior to the patient undergoing orthognathic surgery. A 'treatable' malocclusion should be attained following orthognathic surgery. Orthodontists must ensure that they can manage the 'treatable' malocclusion by actively participating in the patient's surgical plan. Therefore, orthodontic principles and guidelines must be established. Three-dimensional computed tomography should be used to construct the midfacial plane and then to assess discrepancies in the midfacial structures as well as yaw and roll of the bilateral facial structures. Orthognathic surgery should be performed to improve the alignment of such discrepancies to attain a skeletal class I relationship and to attain an aesthetically pleasing face. The surgery-first approach uses osteotomy to solve most of the skeletal and dental problems and to simplify postoperative orthodontic treatment by providing a treatable malocclusion for which mostly only anteroposterior orthodontic movement is required, with minimal transverse or vertical orthodontic movements. Numerous studies have documented the efficacy and long-term stability. Patients undergoing the surgery-first approach benefit from an immediate improvement in facial aesthetics, oral function, and self-confidence, with a shorter total treatment period.