Screw fixation after mandibular sagittal split osteotomy: an intra-oral approach.

Intra-oral, rigid, non-compressive fixation was used in a feasibility study in 10 consecutive sagittal split osteotomies using two 3.5 or 2.7 mm diameter AO screws on each side. Seven patients were prognathic, three were retrognathic, and two had severe mandibular asymmetry. Lower third molars were removed concurrently in three patients. Horizontal and vertical stability was assessed by means of repeated, digitised cephalometry before operation, at 24-48 h and at 6 months. Intermaxillary fixation (IMF) was necessary during the first 48 h in one patient where the lingual fragments were too small. Intermaxillary elastics were used later in three patients. This method was straightforward, reliable, required no skin incisions and stability was similar to that following the use of transbuccal screw fixation. Mean horizontal relapse at 6 months (0.6 mm; maximum: 1.5 mm) was 8% of operative movement. Unsatisfactory occlusion (anterior open bite) necessitated removal of screws at 28 days in one patient. This was carried out intra-orally under local anaesthesia. These results suggest that stable, screw fixation for sagittal split osteotomies can be achieved without recourse to an external approach.