The novel use of customised rapid prototyped osteotomy template in correction of severe mandibular asymmetry: a case report

158 Variation of plate fixation for mandibular advancement with intraoral vertical ramus osteotomy using endoscopically-assisted intraoral rigid or semi-rigid internal fixation: postoperative condylar seating control for mandibular advancement S. Hara ∗ , M. Mitsugi, Y. Tatemoto Department of Oral and Maxillofacial Surgery, Kochi Health Sciences Center, Kochi-city, Japan Background: We have recently controlled intraoperative condylar seating, with adjustable holes such plates as a sliding plate or MOJ plate. However, even when using such plates, postoperative passive condylar seating cannot be done. Objectives: The purpose of the present study was to evaluate the safety and efficacy associated with mandibular advancement by intraoral vertical ramus osteotomy (IVRO) with endoscopicallyassisted intraoral rigid or semi-rigid internal fixation. Methods: The study sample included all patients who had undergone a mandibular advancement by IVRO procedure with endoscopically-assisted intraoral plate fixation from September 2008 to May 2012. A mandibular advancement by IVRO with endoscopically assisted intraoral rigid or semi-rigid internal fixation was used for mandibular advancement. The patients were analysed prospectively, with more than two years of follow-up, and were evaluated in terms of functional results, postoperative complications, and skeletal stability. Findings: A total of 14 patients (bilateral, seven patients with class II; unilateral, seven patients with asymmetry) were included in the present study. The average degree of mandibular advancement was 5.5 ± 1.9 mm (range, 3–9 mm). Both the occlusal relationship and facial appearance in all patients were significantly improved by the surgical-orthodontic treatment, with no major harmful clinical symptoms. In addition, one-screw semi-rigid fixation could control postoperative passive condylar seating. Conclusion: This study showed that mandibular advancement by IVRO with endoscopically assisted, intraoral semi-rigid internal fixation offers a promising treatment alternative for patients with skeletal class II malocclusion or facial asymmetry. http://dx.doi.org/10.1016/j.ijom.2017.02.543 The novel use of customised rapid prototyped osteotomy template in correction of severe mandibular asymmetry: a case report S. Hassan ∗ , K. Kadir, P. Shanmuhasuntharam Department of Oral and Maxillofacial Clinical Sciences, Faculty of Dentistry, University of Malaya, Kuala Lumpur Severe mandibular asymmetry causes both functional and aesthetic disturbance in patient. Managing it can be challenging as the complexity of the bony geometry and other facial structures. Complications such as undercorrection, overcorrection and injury to the inferior dental nerve may arise as it is difficult to control the osteotomy line, shape and amount of osteotomy. Therefore, correct method should be explored to produce the same osteotomy designed cut pre- and postoperatively. In this report, a case of severe mandibular asymmetry which was corrected by using customised rapid prototyped (RP) osteotomy template is described. The measurement of the vol-

ume, shape, osteotomy line and distance from inferior dental canal was established by using computer-aided design (3D Slicer and Autodesk Meshmixer Software) and further osteotomy cut was performed using the fabricated osteotomy template. Intraoperatively, the template was fitted well to the contour of the mandible. Postoperative cone-beam computed tomography revealed that both lower border of mandible has become symmetric and the results were comparable with preoperative planning. In addition, inferior dental nerve was preserved and good aesthetic result was achieved. This report suggested that customised RP osteotomy template could give better accuracy, efficiency and avoid complications in guiding osteotomy in mandibular asymmetry. http://dx.doi.org/10.1016/j.ijom.2017.02.544 Accuracy of orthognathic surgery — a retrospective service evaluation A. Hills ∗ , K. Gowans, A. DiBiase, J. McKenzie, N. Goodger East Kent Hospitals University NHS Foundation Trust, United Kingdom Background: 2700 orthognathic procedures are carried out in England per annum. The multidisciplinary nature of treatment and potential for variations in planning and surgical method means limited data exists on the accuracy of surgery. Inaccurate surgery adversely affects length of treatment, inconveniencing patients as well as detrimentally affecting service provision, finances and allocation of hospital resources. Analysis of surgical accuracy helps identify areas to address to improve outcomes. Objectives: To assess the accuracy of orthognathic surgical process, including presurgical orthodontics, presurgical work-up, laboratory model surgery and surgery itself. Methods: Between 1st January and 31st December 2014, 27 patients underwent maxillary osteotomies at East Kent University Hospital Foundation Trust. A retrospective service evaluation was performed using pre- and postoperative digital lateral cephalometric radiographs. These were superimposed by computer software (Opal, 2010) and a custom analysis used to identify the difference between the pre- and postoperative maxillary positions. Maxillary anterior-posterior movement, along with posterior and anterior impaction were assessed. It was not possible to measure cant or horizontal movements using this method. Results: The mean difference between actual and planned surgical movement of the maxilla in anterior-posterior, posterior impaction and anterior impaction movements was 0.57 mm, 0.96 mm and 0.55 mm respectively. No statistical difference was demonstrated between any of the planned and actual movements (P > 0.05). Conclusion: Surgical maxillary movements can on average be achieved within 1 mm of the planned movement, with anteriorposterior movement being the most accurate. This accuracy is comparable to similar studies using alternative planning and surgical techniques. http://dx.doi.org/10.1016/j.ijom.2017.02.545