[Sagittal Splitting with Screw Fixation in Patients with Mesial Bite Wearing Dentures--planning Surgery and Prosthetic Design]

In fully or partially edentulous patients with mesial bite undergoing surgical correction, the possibilities for avoiding intermaxillary fixation were studied. For stable osteosynthesis of mandibular osteotomies preoperative prostheses are needed in these patients to keep the jaws in their proper relation during surgery. This requires cephalic adjustment of the maxillary cast and articular adjustment of the mandibular cast in the articulator. The mandibular cast is shifted along an aluminum wedge designed to match the inclination of the occlusal plane until the alveolar rests are in proper relation to one another. If the occlusal plane is neglected, uncontrollable tilting of the mandible may occur. This may favor relapses. As Slavicek (1984) showed the mean inclination of the occlusal plane relative to the hinge axis-orbital plane to be 12.87 degrees (scatter 5.99 degrees) with dorsal convergence in 1,213 patients, 3 aluminium wedges with different inclinations were designed. These are suited for 92.5% of all cases with tolerances of +/- 3 degrees. Mandibular casts are pasted to geometric paper and shifted along the aluminium wedge to the desired position; the distance they are shifted is read from the paper. This distance is transferred to the teleradiograph and the changes in profile are checked. Preoperatively, prostheses can then be tailored to match the desired alveolar crest relation. During surgery, these prostheses serve as splints for setting the mandible as designed in the model. The osteotomy fragments are then screwed together transbuccally with miniscrews and clawed washers. The latter provide for a firm seat of the traction screws in the mandible at a safe distance from the mandibular canal. Postoperative intermaxillary fixation can thus be avoided.