Dentin shear strength: Effects of tubule orientation and intratooth location
Dentin shear strength: Effects of tubule orientation and intratooth location
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DOI：
10.1016/s0109-5641(96)80077-7
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发表时间：
1996-03-01
期刊：
影响因子：
5
通讯作者：
Marshall, SJ
中科院分区：
文献类型：
--
作者：
Watanabe, LG;Marshall, GW;Marshall, SJ
目标.牙本质具有高度定向的小管结构，并且小管间牙本质的小管数密度和面积分数随离牙髓的距离而变化。本研究旨在确定牙本质中小管方向对牙本质剪切强度的影响。将第三磨牙切片并制备，以提供来自两个位置（中心和尖突）的样品和具有三个特定小管方向之一的样品。在系列1中，使用两个小管方向对匹配的中冠样本进行了测试。配对t检验用于统计分析。在系列2中，使用三种不同的小管方向测试了来自中央和尖部区域的三个样本。采用双因素方差分析进行统计学分析。每个样品的尺寸约为1 x 1 x 5 mm，并通过单平面搭接剪切法在水合状态下进行测试。两个方向的中冠牙本质的成对牙本质样本的剪切强度分别为72.4 +/- 15.6 MPa和78.4 +/- 13.2 MPa。且无显著性差异（P>0.05;配对t检验）。在第二个系列中，中心位置的样本（小管平行于剪切平面），在旋转90度的方向上施加力，没有表现出显著差异（p>0.05），平均值为53.5 +/- 9.5 MPa。小管沿着样本长轴取向并在垂直于小管方向施加剪切力的情况下进行测试的样本相对于三种取向（83.6 +/- 8.4; 85.2 +/- 13.8; 91.8 +/- 12.7 MPa）具有显著更高（p 0.05;双因素ANOVA）。在三个测试方向中的两个方向上，尖区比中央区更强。结果表明，剪切强度在中央和尖区不同，并依赖于牙本质小管在中央区的方向。剪切强度远大于剪切粘结强度试验中报告的值。这表明，使用剪切测试，牙本质剪切强度远远超过牙本质粘结强度，并且在这种测试中，牙本质断裂是由于牙本质中的缺陷或应力集中造成的。
Objectives. Dentin has a highly oriented tubule structure, and the tubule number density and area fraction of intertublar dentin vary with distance from the pulp. This investigation sought to determine the influence of tubule orientation on shear strength of dentin from samples derived at various intratooth locations.Methods. Third molars were sectioned and prepared to provide samples from two locations (center and cusp) and with one of three specific tubule orientations. In series 1, matched pairs of midcoronal samples were tested using two tubule orientations. A paired t-test was used for statistical analysis. In series 2, three samples from central and cuspal areas were tested using three different tubule orientations. A two-way ANOVA was used for statistical analysis. Each sample had dimensions of approximately 1 x 1 x 5 mm and was tested in a hydrated state by a single plane lap shear method.Results. The paired dentin samples of the midcoronal dentin in the two orientations had shear strengths of 72.4 +/- 15.6 MPa and 78.4 +/- 13.2 MPa. and were not significantly different (p>0.05; paired t-test). In the second series, samples from the center location with tubules parallel to the shear plane with applied force in directions rotated by 90 degrees did not exhibit a significant difference (p>0.05), with an average value of 53.5 +/- 9.5 MPa. Samples oriented with tubules along the long axis of the specimen and tested with shear force applied perpendicular to the tubule direction had significantly higher (p0.05; two-way ANOVA) with respect to the th ree orientations (83.6 +/- 8.4; 85.2 +/- 13.8; 91.8 +/- 12.7 MPa). Cuspal areas were stronger than central areas in two of the three orientations tested.Significance. Results indicated that the shear strength differs in central and cusp areas and is dependent on dentin tubule orientation in the central area. Shear strengths were much larger than values reported in shear bond strength tests. This suggests that dentin shear strength is far in excess of dentin bond strengths using shear tests, and that fractures through dentin in such tests result from flaws or stress concentration in the dentin.