| Summary: | 碩士 === 國立陽明大學 === 生物醫學工程學系 === 104 === The free flap surgery is considered as the gold standard method for reconstruction of the mandibular defect. However, shapes of the mandible contour are different from ethnicity. Therefore, traditional reconstruction plate most be bent to fix the shapes of the mandible contour,but it’s hard to be in contact with the bone to maintain stability. In the literature, MatrixMANDIBLE Preformed Reconstruction Plates seem to be a useful standard device in a scope of indications for load-bearing osteosynthesis of mandibular defect, additionally facilitating a transoral approach for application,but that it’s has limited effects for plate adaptation . In the literature, when this stress repeated many times, the strength of the material may be drastically reduced and ultimately cause failure.
This study used combined CAD/CAE techniques to establish FE models of the mandibular symphysis defect with bone graft treatment, fixed with three new and one traditional reconstruction plates were generated using computed-tomography image stacking and computer-aided design technique. New reconstruction plates were designed including the first type which can fix bone graft in alveolar process to avoid injury of nervous and rooted tooth, and the second type which can fix bone graft similar to the first type but strength the base portion in the bone plate to improve the biomechanical performance, and the other was the third type which can fix bone graft similar to the second type. In addition, the third type can be used in different altitude of alveoli dentales. The new reconstruction plates were stamped by punch with mold which were established by CAD techniques and image processing technique. Stress values and corresponding concentration regions of traditional, the first, the second, and the third reconstruction plates in different bone healing stages after surgery under receiving occlusal force were noted by performing non-linear FE analyses. After manufacturing the new reconstruction plates we conducted functional tests to confirm the efficacy and safety of the proposed the new reconstruction plates. Three functional system tests were conducted, screw test (ASTM F543), bone plate test (ASTM F382), fatigue test.
Simulated results demonstrated that the maximum stress of traditional, RU, ERU and the new reconstruction plate were 546, 116, 21 and 197 MPa. ASTM F382 test results demonstrated that bending stiffness, bending structural stiffness and bending strength of traditional reconstruction plate were 744.75 N/mm、1305878.76 N-mm2、5280 N-mm；bending stiffness, bending structural stiffness and bending strength of the new reconstruction plates were 1911.97 N/mm、2186019.04 N-mm2、7396.67 N-mm. Fatigue test results demonstrated that both traditional reconstruction plate and the new reconstruction plate were achieved the request of 200000 tests cyclic.In conclusion, New reconstruction plate with preformed techniques can fix bone graft in alveolar process to avoid of injury of nervous and rooted tooth and enhanced structural stability can restore occlusal function in mandibular symphysis defect.
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