上颌All-on-4修复种植体在不同牙弓形态中应力分布的三维有限元分析

目的：利用有限元法探讨上颌牙列缺失应用All-on-4修复时种植体在3种牙弓形态模型中应力分布的差异，为临床提高种植体成功率提供客观参数。方法：参照3M公司MBTTM牙弓模板，应用SolidWorks 2013软件建立All-on-4种植修复的3种牙弓形态上颌无牙颌有限元模型（尖圆形、方圆形和卵圆形），设定皮质骨层为2 mm，种植体长度为13 mm，前牙区2颗种植体平行植入，后牙区2颗种植体在颌骨内沿近远中方向与牙长轴成0°、15°、30°和45° 4种角度，所有种植体均固定于上部结构。通过2种加载方式在上部结构施加100 N压力模拟咀嚼受力，应用有限元软件Abaqus 6.13运算测得种植体在上颌模型的Von-Mises应力值。结果：测得种植体周围Max von-Mises应力值均出现在皮质骨层，不同牙弓形态模型中应力分布不同，方圆形牙弓种植体周围应力随种植体角度增加而增大；卵圆形牙弓后牙区最大应力值出现在种植体倾斜15°时，前牙区应力在种植体倾斜超过15°后明显提高；尖圆形牙弓种植体周围应力在种植体倾斜45°时显著增大。结论：牙弓形态对种植体周围应力分布有显著影响，All-on-4修复上颌牙列缺失时，方圆形牙弓应尽量减少种植倾斜体角度，卵圆形牙弓种植体倾斜角度不宜超过15°，尖圆形牙弓应避免种植体倾斜角度超过30°。

3-dimensional finite element analysis on stress distribution in maxillary with All-on-4 implants in different arch forms

Objective To explore the effect of different arch forms of maxillary models on stress distribution of periimplant of All-on-4implants with 3-dimensional finite element,and to provide evidence for the improvement of implant achievement ratio in clinic.Methods 3-dimensional finite element analysis models of Tapered,Square and Ovoid arch form maxillary based on the MBTTM Arch Form Templates were constructed by using Solidworks software.The cortical bone thickness was defined as 2mm at all points.The implants with 13 mm in length were inserted between the mental foramina.The 2posterior implants were set at 4inclination angle,from 0°to 45°.All implants were splinted with superstructure.A 100 Npressure was applied to 2kinds of loading positions on the superstructure models.The maximum Von-Mises stress on cortical bone around the implants was measured by using Abaqus software.Results The maximum Von-Mises value in maxillary cortical bone with All-on-4implants in 3arch forms showed significant differences.In Square model the concentration of stress was advanced with the increasing of implant inclination angle;In Ovoid model,the maximum Von-Mises value was observed at 15°in posterior region,and was increased significantly by pasted 15°in anterior region;In Tapered model,the Maximum Von-Mises value was increased greatly at 45°.Conclusion Arch forms have appreciable impact on stress distribution of peri-implant.In Square arch form,the inclination of implant should be avoided;in Ovoid arch form,the inclination angle should be under 15°;in Tapered arch form,the inclination should be under 30°.