A modified technique to determine the desired length of bicortical screws in sagittal split osteotomies

Abstract

Since the original description of the bilateral sagittal split osteotomy (BSSO) by Obwegeser, several techniques have been described to avoid maxillomandibular fixation. These techniques of rigid internal fixation include use of lag screws,’ position screws,’ and miniplates.” Since 1988, the self-tapping position screw technique has been used in our institute for internal fixation of the BSS0.4 Until April 1995, 970 patients (1,935 sites) have been treated accordingly. However, in 8 patients, loosening of the screws occurred in the first postoperative week, which resulted in occlusal discrepancy and required reoperation. Loosening of the screws can be explained by apposition of the proximal and distal fragments under tension, a thin medial cortical bone layer, or use of short screws. To prevent the last, the use of commercially available depth-measuring devices is advocated. Another method to measure the length of the position screws in a rapid and accurate fashion is presented.