下颌骨缺损钛重建板修复的生物力学分析

Biomechanical analysis of human mandible reconstructed with titanium-plate

背景:钛重建板是重建下颌骨最常用金属材料,术后钛重建板断裂和钛钉松动最终导致手术的失败。研究分析,钛重建板断裂的钛钉松动的原因很多,包括钛钉的完全承载,余留牙的咬合力过大,钛重建板长度过长,钛钉数量过少,手术中预弯机械损伤等。目的:首次建立正常下颌骨和下颌骨缺损钛重建板重建的三维有限元模型,并对其生物进行力学分析。方法:选择一名咬牙合关系正常的成年男性为志愿者,对其下颌骨进行多层螺旋CT扫描,获得原始数据。基于CT扫描图像原始数据,利用高性能电子计算机及逆向工程软件Mimics建立正常下颌骨及钛重建板重建下颌骨三维模型及三维有限元模型,模拟垂直和斜向咬牙合状态下,正常下颌骨及钛重建板重建下颌骨应力分布情况。结果与结论:①获得了三维有限元模型:正常下颌骨由80044个节点,431899个单元组成;下颌骨缺损(SS型)钛重建板重建下颌骨由68400个节点和247379个单元组成。②正常下颌骨在后牙垂直咬牙合下vonMises应力较大区域分布在下颌升支前缘20.15MPa、下颌角19.45MPa和髁颈部15.35MPa。钛重建板重建下颌骨模型的应力分布,垂直咬牙合状态下,升支前缘vonMises应力最大值19.34MPa,髁颈部10.21MPa,下颌角18.56MPa,钛重建板中部24.58MPa,钛钉18.35MPa。模拟斜向45°咬牙合状态下vonMises应力分布最大值,钛重建板重建下颌骨右侧髁颈部升支前缘19.34MPa,右侧髁颈部10.21MPa,下颌角18.56MPa,钛重建板24.58MPa,钛钉18.35MPa。结果说明钛重建板重建下颌骨应力分布,明显集中于钛重建板,钛钉,与正常对比应力分布不均匀,因此影响下颌骨缺损钛重建板重建的牢固性。

BACKGROUND： Mandibular reconstruction plate is the most commonly used metals. Titanium plate titanium screw fracture and loosening leads to surgical failure. Studies show that the causes for titanium plate titanium screw fracture and loosening include overload, occlusal force, plate length, number of titanium screw, and mechanical injury. OBJECTIVE： To establish normal mandible and mandibular defect reconstruction plate finite element model, and analyze its biomechanics. METHODS： Based on the original CT scan image data of 1 male volunteer with normal occlusion relationship, using high-performance computer and reverse engineering software Mimics, normal mandible and mandibular reconstruction plate three-dimensional model and three-dimensional finite element model were established to simulate the vertical and oblique teeth together state, normal plate reconstruction of the mandible and the mandibular stress distribution. RESULTS AND CONCLUSION： Three-dimensional finite element model was obtained. The normal mandible comprised of 80 044 nodes and 431 899 modules; mandibular defects （SS type） titanium mandibular reconstruction was composed of 68 400 nodes and 247 379 units. Under normal mandibular teeth in the combined posterior vertical large area, the von Mises stress was distributed in the mandibular ramus front 20.15 MPa, mandibular angle and condylar neck 19.45 MPa 15.35 MPa. von Mises stress of titanium plate mandibular reconstruction model under vertical teeth together was ascending branch of the maximum front 19.34 Mpa, condylar neck 10.21 Mpa, mandibular angle 18.56 Mpa, titanium central 24.58 MPa, screws 18.35 MPa. Simulated oblique 45° teeth together under the maximum von Mises stress distribution, the reconstruction of mandibular titanium condylar neck and ramus on the right front was 19.34 MPa, right condyle neck 10.21 Mpa, mandibular angle 18.56 MPa, titanium 24.58 MPa titanium nail 18.35 MPa. Stress of reconstruction of mandibular stress distribution plate is focused on the titanium plate, titanium screw, which is distributed unevenly compared with the normal stresses, thereby affecting stability of titanium plate reconstruction of mandibular defects.