The aim of this study is to convert a simple, expansion screw used for rapid palatal expansion into a bone-borne symphysis distractor and to introduce two different modeling techniques for adapting of the screw to the anatomy of symphysis before surgery. The techniques will be presented on two cases. The cases used in this study showed mandibular transverse deficiency and lower anterior crowding. In the first case the distractor was fabricated on a study model obtained by cephalometric modeling technique. In the second case the SLA (Stereo-Litographic Apparatus) biomodeling technique was used. The active unit is a simple rapid palatal expansion screw and the parts used to fix the miniscrews to bone during surgery are prefabricated from titanium footplates. Both of the distractors were applied by the same surgeon following the same surgical procedures. During the surgical procedure, although the adaptation of the distractor to the symphyseal region was acceptable in the cephalometric modeling technique, the arms of the distractor needed minor, secondary bendings for perfect fit. During the surgical procedure of the distractor prepared by SLA biomodeling technique there was no need for any additional adaptation. In both of the cases sufficient widening and parallel distraction pattern was obtained; new bone was radiologically observed after the consolidation period. The lower crowding was resolved using the space obtained by distraction; no complication was observed. In conclusion although both of the techniques were successful, the distractor adaptation in SLA biomodeling technique was superior in shortening the surgical procedure and minimizing the possible complications.

Keywords: Symphyseal distraction, SLA biomodeling technique, Cephalometric modeling technique metric modeling technique