假体双延伸肩台拉力螺钉固位设计的生物力学评价

Biomechanical evaluation of dual abutments with lag screws for fixation of mandibular prosthesis

目的:对双延伸肩台拉力螺钉固位方式进行生物力学评价,探索合理的下颌骨假体固位方式。方法:选择1例华东地区正常成年男性,建立基于CT图像数据文件的下颌骨三维有限元模型,计算机模拟半侧下颌骨缺损,设计双延伸肩台拉力螺钉固位方式的下颌骨假体修复,分析4种工况条件下固位方式的应力分布特征。采用SAS6.12软件包进行t检验及方差分析。结果:4种工况条件下,双延伸肩台拉力螺钉固位结构应力完全呈等强度分布(P=0.2997),平均受力值远低于钛材的许应力值;固位结构周围骨组织所承受的应力分布合理(P=0.9377),与正常松质骨最佳应力值间无统计学差异(P=0.7083)。结论:下颌骨假体双延伸肩台拉力螺钉固位方式应力分布合理,且有利于周围骨组织的改建。

PURPOSE： Biomechanical analysis was performed on dual abutments with lag screws to explore the reasonable fixation method of mandibular prosthesis. METHODS： Three dimensional finite element model of the mandible was established based on CT images of a normal occlusion adult from east China released as DICOM file by ANSYS software. The mandibular prosthesis with fixation of dual abutments with lag screws was designed by applying CAD software for repair of hemimandibular defect in the computer. The stress distribution on the fixation structures under four loading condition was investigated. The data were analysed statistically with SAS6.12 software package. Student t test and ANOVA were used for comparing the differences. RESULTS： The structures of dual abutments with lag screws presented with equal stress distribution under four loading conditions （P=0.2997）, the average maximum value was by far less than yielding strength of the titanium. The stress distribution of bony tissue surrounding the fixation structures was also reasonable and had no significant difference with optimal stress of normal cancellous bone in statistics （P=0.7083）. CONOLUSION： Dual abutments with lag screws for fixation of mandibular prosthesis underwent reasonable stress distribution and benefited remodeling of surrounding bone.