Assessment of Predictability of Straight Locking Miniplate for Accuracy in Bimaxillary Orthognathic Surgery

Abstract

Inaccurate positioning of the maxilla leads to less than ideal functional and aesthetic outcomes in orthognathic surgery. Previously reported techniques for positioning the maxilla required intra operative measurement using internal and external reference points. [2] These intra operative measurement techniques had been shown clinically reliable, but for accurate repositioning, intra operative measurement often had to be repeated several times until the maxilla was moved into the planned position, which was time-consuming and troublesome. It is still difficult to exclude the possibility of error incidental to the measurement procedure, even if it is performed by experienced surgeons with the utmost care, especially during multidirectional moves. [3] The bilateral sagittal split osteotomy (BSSO) is one of the main orthognathic surgery procedures used for managing skeletal mandibular excess, deficiency or asymmetry. It is known to be a technique-sensitive procedure with high reported incidences of inferior alveolar nerve injury, bad splits and post-surgical relapse. [4] Post-surgical relapse has been classified into immediate and delayed relapse. The immediate relapse has been mainly attributed to improper seating of the mandibular condyles in the glenoid fossae whereas delayed relapse has been attributed to unstable occlusion, inadequate fixation and condylar resorption. [5] Various authors have stressed avoiding condylar displacement and have suggested intraoperative guidance of the condylar position. [6] Different condylar positioning devices (CPDs) have been investigated for effectiveness in re-establishing the preoperative condylar position following BSSO with contradicting outcomes as regards to both skeletal stability and temporomandibular disorders (TMD). These devices ranged from intra operative monitoring devices; such as infrared diodes or ultrasonography to various instruments that attach the proximal condyle-bearing segment to either osseous or dental fixed distal anchoring sites[7,8]. Some clinicians have investigated the feasibility of intraoperative awakening of the patient before fixation of the proximal segment. [9]