Thesis (Ph.D.) - Cairo University - Faculty of Oral and Dental Medicine - Department of Oral and Maxillofacial Surgery

Objectives: The prominence of the maxillary-zygomatic complex makes an important contribution to facial aesthetics. The increased success and experience achieved with Le Fort osteotomy turned the attention to develop surgical techniques to cope with the hypo-plastic mid-face. This study aimed to compare between Virtual model versus conventional model surgery in correction of mid-face deficiency. Methods: Fourteen patients with mid face hypoplasia were allocated randomly for mid-face osteotomy.Seven Patients were subjected to conventional model surgery utilizing Face bow transfer and dental surgical stents. The other seven patients were subjected to Computed Tomography (CT) and dental casts scanning. CT images were transformed into initial virtual models. The scanned cast models were registered over the virtual models.The composite 3D models with planned Virtual osteotomies were printed forming stereo-lithographic models. Titanium plates were pre-bent and screw holes were marked to the stereo-lithographic models for construction of surface templates that locate both screw holes and osteotomy lines intraoperatively.The pre-bent plates were installed by placing screws in the predetermined screw holes. Tightening of the screws advanced the depressed mid-face. The fourteen patients were clinically and radiographicaly evaluated pre and post-operatively. Antro-posterior mid face advancement was measured and statistically evaluated for both groups.Results: The postoperative antro-posterior advancement difference between the right and left sides of the advanced mid-face in all cases of the study group was compared with that of the control group and show statistically significant difference with average difference = 3.5386 (P Value = 0.0048). Conclusion: Computer guided surgery was proved to be more reliable technique for mid face advancement than the conventional model surgery regarding the osteotomy level, configuration and symmetric movement

Issued also as CD