Influence of mandibular fixation method on stability of the maxillary occlusal plane after occlusal plane alteration.

Department of Oral and Maxillofacial Surgery, Tokyo Dental College, Mihama-ku, Chiba, Japan.
The Bulletin of Tokyo Dental College 05/2009; 50(2):71-82. DOI: 10.2209/tdcpublication.50.71
Source: PubMed

ABSTRACT In this study, we investigated how method of mandibular fixation influenced longterm postoperative stability of the maxilla in Class III cases. In particular, we investigated change in the maxillary occlusal plane after Occlusal Plane Alteration. Therefore, we focused on change in the palatal plane to evaluate stability of the maxillary occlusal plane, as the position of the palatal plane affects the maxillary occlusal plane. This study included 16 patients diagnosed with mandibular protrusion. Alteration of the occlusal plane was achieved by clockwise rotation of the maxilla by Le Fort I osteotomy and mandibular setback was performed by bilateral sagittal split ramus osteotomy. We analyzed and examined lateral cephalometric radiographs taken at 1 month, 3 months, 6 months, and 1 year after surgery. Stability achieved by two methods of mandibular fixation was compared. In one group of patients (group S) titanium screws were used, and in the other group (group P) titanium-locking mini-plates were used. No significant displacement was recognized in group S, whereas an approximately 0.7mm upward vertical displacement was recognized in the anterior nasal spine in group P. As a result, not only the angle of the palatal plane and S-N plane, but also occlusal plane angle in group P showed a greater decrease than that in group S. The results suggest that fixing the mandible with screws yielded greater stability of the maxilla and maxillary occlusal plane than fixing the mandible with titanium plates.

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    ABSTRACT: Postsurgical changes in the condylar position are of great importance to surgical stability, especially in asymmetric double-jaw surgery. The aims of this study were to evaluate positional changes of the condyle up to 12 months after surgery in patients with Class III malocclusion and to identify the factors affecting postsurgical condylar position. The study included 33 adult patients diagnosed with skeletal Class III malocclusion who underwent bimaxillary surgery and had full cone-beam volumetric imaging (CBVI) records up to 1 year after surgery. The CBV images were obtained before surgery and 2 weeks, 3 months (T2), 6 months (T3), and 12 months after surgery. Condyles with deviated and nondeviated sides were examined separately regardless of the degree of asymmetry. Analyses of variance and multiple regression analysis were performed to identify factors that could affect the position of the mandibular condyles. The condyles exhibited anterior displacement at T2, which returned to a more distal position afterward in the axial view, and an inward rotation in the coronal view up to T3. From the sagittal view, the deviated and nondeviated condylar sides rotated forward and remained stable after T2. The degree of menton deviation affected the angle of condylar rotation (horizontal angle). The results of this study suggest that condyles tend to move in a certain direction, and this can influence postsurgical relapse up to 6 months after surgery. However, they remain relatively stable afterward.
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