松质骨和皮质骨厚度对种植体周围应力分布的影响

目的: 观察不同松质骨和皮质骨厚度下种植体周围应力分布的情况,探讨骨组织厚度比例及总厚度对种植体可靠性的影响。方法: 使用Abaqus软件建立颌骨三维有限元模型并进行计算,研究侧向力和轴向力作用下不同厚度比例的松质骨和皮质骨对种植体周围应力分布的影响,其中松质骨和皮质骨的比值分别为3:1、2:1、1:1、1:2和1:3,两者的总厚度分别取0.5、1.0、2.0、3.0和4.0 mm。结果: 皮质骨、松质骨和种植体表面最大应力随着松质骨和皮质骨总厚度的增大而递减,总厚度在0.5~2.0 mm区间内减小速度较快,在2.0~4.0 mm区间内减小速度较慢。对于不同厚度比例的松质骨和皮质骨,种植体颈部皮质骨内的最大应力在总厚度为2.0 mm时取得最小值。当总厚度小于2.0 mm时,种植体颈部皮质骨内的最大应力值随着总厚度的减小而快速升高;当总厚度大于2.0 mm时,种植体颈部皮质骨内的最大应力值随着总厚度的增大而缓慢升高。结论: 松质骨和皮质骨厚度的比值及总厚度均对种植体周围的应力分布有显著影响;在种植体手术中松质骨和皮质骨的总厚度应大于或等于2.0 mm,最佳值为2.0 mm。

Influence of thickness of cancellous bone and cortical bone in stress distribution in vicinity of an implant

Objective: To investigate the stress distribution surrounding an implant under different thickness of cancellous bone and cortical bone, and to analyze the influence of thickness ratio and total thickness of bone tissues on the reliability of an implant.Methods: By using the commercial finite element method software Abaqus, a simplified three-dimensional model of a jawbone consisting of a cancellous bone, a cortical bone, an implant, and a ceramic crown was constructed, and then the computation was performed.Under the condition that the system was loaded by lateral and normal stresses, the influence of thickness ratio and total thickness of cancellous bone and cortical bone in the stress distribution surrounding the implant was studied, where the thickness ratios were 3:1, 2:1, 1:1, 1:2, and 1:3; the total thickness were 0.5, 1.0, 2.0, 3.0 and 4.0 mm, respectively.Results: The maximum stresses on the cortical bone, the cancellous bone as well as the implant were all found to decrease with the increasing of the total thickness of cortical and cancellous bones, with a higher decreasing rate in the range between 0.5-2.0 mm and a lower decreasing rate between 2.0-4.0 mm.More importantly, the maximum value of stress in the cortical bone within the neck region of the implant was observed to increase dramatically via reducing the total thickness below 2 mm, while it was increased insignificantly when the total thickness was above 2.0 mm.Conclusion: The thickness ratio and the total thickness of cancellous bone and cortical bone have strong influence in the stress distribution surrounding the implant. In dental implantation surgery, the total thickness of cancellous bone and cortical bone should be at least 2 mm, and therefore 2 mm is an optimal value.