Comparative evaluation of different fixation techniques for sagittal split ramus osteotomy in 10 mm advancements. Part two: Finite element analysis.

PURPOSE: To evaluate three rigid, stable fixation methods for sagittal split ramus osteotomy (SSRO), using finite element analysis. The hypothesis is that a customized miniplate presents better stress concentration and distribution. MATERIALS AND METHODS: A 3D model of a hemimandible was created, and a 10-mm-advancement SSRO was simulated and fixed as follows: 3-DCP group - one custom miniplate fixed by eight screws; 4-H2P group - two miniplates of four holes each, fixed by eight screws; and 6-H2P group - two miniplates of six holes each fixed by 12 screws. After a vertical loading of 100 N, the values for von Mises stress, modified von Mises stress, and maximum and minimum principal stresses were measured. RESULTS: The area of maximum principal stress was similar for the three groups - located in the upper miniplate, in the screw near the proximal segment osteotomy. The maximum von Mises stresses were 1580.4 MPa, 1005 MPa, and 977.56 MPa for the 3DCP, 4-H2P, and 6-H2P groups, respectively, showing an allowable displacement of 2.57 mm, 1.62 mm, and 1.52 mm for the 3DCP, 4-H2P, and 6-H2P groups, respectively. CONCLUSION: The customized miniplate did not present better stress distribution than two commonly used types of fixation. Fixation with two straight miniplates, either with four or six holes, offers adequate resistance for 10 mm linear advancements.

Evaluation of patients' perceptions of alterations after chin bone graft harvesting.

OBJECTIVE: To evaluate patients' perceptions of alterations occurring after chin bone harvesting. MATERIALS AND METHODS: Thirty patients were evaluated subjectively by visual analog scale-related sensitivity, facial aesthetics, eating, speaking, and lower lip movement, during 12 months. Objective analysis used the static light touch neurosensorial test. The statistical analysis was executed with Friedman test with P < 0.05 for both samples. RESULTS: Subjective analysis revealed no alterations (1) to facial aesthetics, eating, speaking or lower lip movement but sensitivity of the mental region went from a lot of alteration initially (5) to little at the end of the study (3). Objective analysis results showed normal sensitivity (1) in the region after 12 months. CONCLUSION: The discrepancy between subjective and objective analyses may be indicative of the limited precision of clinical testing for subjective impressions assessment.

Clinical evaluation of association of bovine organic osseous matrix and bovine bone morphogenetic protein versus autogenous bone graft in sinus floor augmentation.

PURPOSE: The purpose of the present study is to evaluate clinically and radiographically the behavior of the association between bovine organic osseous matrix (BOM) and bovine bone morphogenetic protein (bBMP) versus autogenous bone graft in promoting bone healing in maxillary sinus lifting procedures. MATERIALS AND METHODS: Ten nonsmoking and systemically healthy patients who needed bilateral maxillary sinus grafting for the placement of osseointegrated implants were treated. In all patients, 1 side was selected as test (bBMP + BOM) and the other as control using autogenous particulated bone graft from mandibular ramus. After a period varying from 6 to 11 months, the implants were placed. The radiographic analysis was realized by panoramic-rx. The clinical analysis consisted of transoperative evaluation by visual observation of bone formation of grafted area and initial stability of implants. RESULTS: Radiographically, the images were evaluated observing radio-opaque aspect. Clinically, a better bone formation pattern of the grafted area in the side grafted with autogenous bone could be observed. The initial stability of the implants in the side grafted with autogenous bone was better than in the test side. The placement torque of the implants in the test side was more than 30 N-cm. CONCLUSIONS: In the present study, the association of bovine organic osseous matrix and bBMP as a growth factor showed different results when compared with autogenous graft. It was observed in the absence of an radio-opaque image, making it difficult to select the implants. Clinically, the bone formation was partial and showed the presence of the fibrous tissue in the grafted area when using the association of bovine organic osseous matrix and bBMP, and the placement torque of implants was less than the control side.