Department of Oral Implantology and Regenerative Dental Medicine, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan.
J Periodontol. 2011 Jul;82(7):1061-70. doi: 10.1902/jop.2010.100237. Epub 2010 Dec 28.
The mechanism by which the microthread implant preserves peri-implant crestal bone is not known. The objective of this research is to assess the effect of microthreads on the magnitude and direction of the stress at the bone-implant interface using finite element analysis modeling.
Three-dimensional finite element models representing the microthreaded implant (microthread model) and smooth surface implant (smooth model) installed in the mandibular premolar region were created based on microscopic and computed tomography images. The mesh size was determined based on convergence tests. Average maximum bite force of adults was used with four loading angles on the occlusal surface of the prosthesis.
Regardless of the loading angle, principal stresses at the bone-implant interface of the microthread model were always perpendicular to the lower flank of each microthread. In the smooth model, stresses were affected by the loading angle and directed obliquely to the smooth interface, resulting in higher shear stress. The interfacial stresses decreased gradually in the apical direction in both models but with wavy pattern in the microthread model and smooth curve for the smooth model. Although peak principal stress values were higher around the microthread implant, peri-implant bone volume exhibiting a high strain level >4,000 μ was smaller around the microthread implant compared to the smooth implant.
Stress-transferring mechanism at the bone-implant interface characterized by the direction and profile of interfacial stresses, which leads to more compressive and less shear stress, may clarify the biomechanical aspect of microthread dental implants.
微螺纹种植体维持种植体周围嵴骨的机制尚不清楚。本研究的目的是使用有限元分析模型评估微螺纹对骨-种植体界面上的应力大小和方向的影响。
根据微观和计算机断层扫描图像创建了代表微螺纹种植体（微螺纹模型）和光滑表面种植体（光滑模型）的三维有限元模型。网格大小基于收敛性测试确定。采用成人平均最大咬合力，并在修复体的咬合面上施加四个加载角度。
无论加载角度如何，微螺纹模型骨-种植体界面的主应力始终垂直于每个微螺纹的下侧。在光滑模型中，应力受加载角度的影响，并向光滑界面倾斜，导致更高的剪切应力。在两种模型中，界面应力在根尖方向逐渐减小，但在微螺纹模型中呈波浪形，在光滑模型中呈光滑曲线。虽然微螺纹种植体周围的峰值主应力值较高，但种植体周围骨体积表现出高应变水平>4000μ的区域，微螺纹种植体周围的区域小于光滑种植体周围。
骨-种植体界面的应力传递机制由界面应力的方向和轮廓决定，这导致更多的压缩和更少的剪切应力，这可能阐明了微螺纹牙科种植体的生物力学方面。
