Finite Element Stress Analysis of Keyhole Plate System in Sagittal Split Ramus Osteotomy.

A new miniplate applied differently from conventional application method for bone fixation has been developed. The novel approach is the insertion of the screw into the bone before miniplate installation. This study aimed to assess the stress distribution of a newly designed Yang's Keyhole (YK)- plate for segmental-bone fixation during sagittal split ramus osteotomy (SSO). Moreover, the effectiveness of the YK-plate system based on the clinical results was determined. The YK-plate system has a widened hole in the anterior region to permit a screw-head to be screwed through the system. The stress distribution using the finite-element analysis method was compared between in the case of the YK-plate system and the case of existing mini-plate fixation technique. Moreover, the clinical results of patients were evaluated during the follow-up examination periods. No critical complications in any of the six patients were reported during the four-month follow-up period. The result of the stress distribution using finite-element analysis showed a similar trend in all four fixation methods. The YK-plate system can be applied to fixation during SSO and allow for mechanically stable and convenient application.

Surgically assisted rapid palatal expansion with tent screws and a custom-made palatal expander: a case report.

Rapid palatal expansion(RPE) with the tooth-born appliance is not sufficient to apply to the patients with periodontal problem or insufficient tooth anchorage, and it leads to tipping of the anchorage teeth and increasing teeth mobility and root resorption. To avoid these disadvantages, we present the case using palatal screws and custommade palatal expander. A 23-year-old patient underwent surgically assisted rapid maxillary expansion with the Hyrax expansion using 4 tent screws. The study models were used to measure the pre-/-post surgical width of the anterior and posterior dental arches with a digital sliding caliper. In the result, the custom-made palatal expander with 4 tent screws is suitable for delivering a force to the mid-palatal suture expansion. And it is low cost, small sized and simply applied. The results indicated that maxillary expansion with the custom-made palatal anchorage device is predictable and stable technique without significant complications in patients.

Design and application of hybrid maxillomandibular fixation for facial bone fractures.

PURPOSE: A novel maxillomandibular fixation (MMF) procedure using a skeletal anchorage screw (SAS) (in the maxilla) and an arch bar (in the mandible), which we call "hybrid maxillomandibular fixation," was explored in this study. The aims of the study were to examine the efficacy of our hybrid MMF method and to compare periodontal tissue health and occlusal rehabilitation among 3 MMF methods. MATERIALS AND METHODS: In total, 112 patients who had undergone open reduction at the Department of Oral and Maxillofacial Surgery between September 2005 and December 2012 were selected for this study. The participants were assigned to one of the following groups: SAS (maxilla), SAS (mandible), SAS-arch bar, or arch bar-arch bar. Periodontal health was evaluated using the Gingival Index, and the perioperative occlusal reproducibility was evaluated using a score of 1 to 3. Statistical analysis was performed using parametric tests (Student t test or 1-way analysis of variance followed by post hoc Tukey test). RESULTS: In the Gingival Index comparison performed 1 month after the surgery, only the group using the arch bars and wiring was significantly different from the other groups (P < 0.05). The occlusal reproducibility scores were not significantly different. The pain and discomfort of the patients were reduced in the hybrid MMF group. CONCLUSIONS: The hybrid MMF takes advantage of MMF using both arch bars and SASs for mandibular fractures. In addition, it overcomes many problems presented by previous MMF methods.