Ferrari M, Mannocci F, Vichi A, Cagidiaco M C, Mjör I A
University of Siena, Italy.
Am J Dent. 2000 Oct;13(5):255-60.
To evaluate in vitro the dentin morphology in root canals in terms of tubule orientation, density and increase in surface area after etching.
Thirty anterior teeth were divided in 3 groups at random: the samples of Group 1 were used to study tubular morphology in SEM. Groups 2 and 3 samples were etched with 32% phosphoric acid. The teeth in Group 2 were examined by SEM without further treatment. The samples in Group 3 were treated with a bonding system and fiber posts were luted into the canal. These teeth were then processed for evaluation of hybrid layer formation and resin tags in dentin tubules. The observations were made according to location in the root dentin, tubule density was estimated, and the increase in area available for bonding after etching was calculated.
The observations revealed variability in tubule density and orientation within different areas of any one sample. Statistically significant differences in the density of tubules were found depending on location. The dentin surface area available for bonding increased by 202% after etching in the cervical third, 156% in the middle third, and 113% in the apical third of the root dentin. Group 3 samples showed that the thickness of the hybrid layer depended on the density of tubules. In the sectors with a low density of tubules, the hybrid layer was significantly thinner than in areas with a higher density of tubules. The increase in dentin surface area might be responsible for the enhanced bond strength after acid etching, but not all areas exhibited equal responses to etching.
在体外评估根管内牙本质的形态，包括小管方向、密度以及酸蚀后表面积的增加情况。
30颗前牙随机分为3组：第1组样本用于扫描电子显微镜（SEM）下研究小管形态。第2组和第3组样本用32%磷酸进行酸蚀。第2组牙齿未经进一步处理直接用SEM检查。第3组样本用粘结系统处理，然后将纤维桩粘结到根管内。随后对这些牙齿进行处理，以评估牙本质小管内混合层的形成及树脂突情况。根据牙根牙本质中的位置进行观察，估算小管密度，并计算酸蚀后可用于粘结的面积增加量。
观察发现，任何一个样本不同区域内小管密度和方向存在差异。根据位置不同，小管密度存在统计学显著差异。牙根牙本质颈段酸蚀后可用于粘结的牙本质表面积增加202%，中段增加156%，根尖段增加113%。第3组样本显示，混合层厚度取决于小管密度。在小管密度低的区域，混合层明显比小管密度高的区域薄。牙本质表面积的增加可能是酸蚀后粘结强度增强的原因，但并非所有区域对酸蚀的反应都相同。
