Universidade Federal de Uberlândia - UFU, Department of Periodontology and Implantology, Uberlândia, MG, Brazil.
Universidade Federal de Uberlândia - UFU, Department of Operative Dentistry and Dental Materials, Uberlândia, MG, Brazil.
Braz Oral Res. 2020 Nov 13;35:e001. doi: 10.1590/1807-3107bor-2021.vol35.0001. eCollection 2020.
Three-point bending test is the most common mechanical test used for quantifying the biomechanical quality of bone tissue and bone healing in small animals. However, there is a lack of standardization for evaluation of bone repair by cortical perforation. The aim of this study was to determine the influence of bone defect position in the proximal metaphysis of rat tibias during load application and different span configuration on the three-point bending test outcomes. Cortical defects with 1.6 mm diameter were created at a standardized location on the medial surface of 60 tibias of male Wistar rats. The animals were euthanized 7 days after surgery. Five specimens were used to create 3D models for finite element analysis using high-resolution micro-CT images. Two spans (6 and 10mm) and three positions of the bone defect in relation to the load application (upward, frontal and downward) were evaluated experimentally (n = 10) and in finite element analysis (n = 5). Maximum load (N) and stiffness (N/mm) were statistically analyzed with 2-way ANOVA and Tukey test (α = 0.05). The results demonstrated that span and orientation of the bone defect significantly influenced the fracture pattern, stress distribution and force versus displacement relation. Therefore, reliable outcome can be achieved creating the bone defect at 8 mm from the extremity of the proximal epiphysis; placing a 10 mm distance span and downward facing defect position to allow a better distribution of stress and more fracture patterns that reached the bone defect target area with less intra-group variability.
三点弯曲测试是最常用于量化小动物骨组织和骨愈合生物力学质量的机械测试。然而，皮质穿孔评估骨修复的方法缺乏标准化。本研究旨在确定在大鼠胫骨近端干骺端施加负荷时骨缺损位置和不同跨度配置对三点弯曲测试结果的影响。在雄性 Wistar 大鼠 60 根胫骨的内侧表面的标准化位置上创建直径为 1.6 毫米的皮质缺损。手术后 7 天处死动物。使用高分辨率微 CT 图像对 5 个标本进行三维建模，用于有限元分析。实验（n = 10）和有限元分析（n = 5）评估了两个跨度（6 和 10mm）和三个骨缺损相对于负荷施加的位置（向上、正面和向下）。使用双因素方差分析和 Tukey 检验（α = 0.05）对最大载荷（N）和刚度（N/mm）进行统计学分析。结果表明，跨度和骨缺损的方向显著影响骨折模式、应力分布和力与位移关系。因此，通过在距近端骨骺末端 8mm 处创建骨缺损、放置 10mm 跨度和面向下方的缺损位置，可以实现可靠的结果，从而更好地分布应力，产生更多达到骨缺损目标区域的骨折模式，组内变异性更小。
