Huang T J, Schilder H, Nathanson D
Boston University School of Graduate Dentistry.
J Endod. 1992 May;18(5):209-15. doi: 10.1016/S0099-2399(06)81262-8.
The objective of this study was to determine whether significant differences exist between the mechanical properties of human dentin from treated pulpless teeth and dentin from normal vital teeth. Dentin specimens (n = 262) were obtained from 54 freshly extracted normal vital human teeth and 24 treated human pulpless teeth. These specimens were subjected to different experimental conditions (wet, air dried, desiccated, and rehydrated). Compression, indirect tensile, and impact tests were conducted to measure the mechanical properties of those specimens. All data obtained were analyzed with t tests. The results showed that the dehydration of dentin increases the Young's modulus, proportional limit (in compression), and especially the ultimate strength (in both compression and tension). Substantial dehydration changes the fracture characteristics of dentin specimens under static compressive and indirect tensile loadings. The measurements of impact-breaking energies of desiccated dentin were not found to be significantly decreased. The compressive and tensile strengths of dentin from treated pulpless teeth obtained in this study do not appear to be significantly different from those of normal dentin (p > 0.05), while the mean values of Young's modulus and proportional limit in compression tests appear to be lower. Fifty percent of the dentin specimens from treated pulpless teeth exhibit greater plastic deformation than normal dentin in compression. The results of this study do not support the theory that dehydration after endodontic treatment per se weakens dentin structure in terms of compressive and tensile strengths. Other mechanical properties of treated pulpless teeth, however, may not be the same as those of normal vital teeth.
本研究的目的是确定经过处理的无髓牙的人牙本质与正常活髓牙的牙本质在力学性能上是否存在显著差异。从54颗新鲜拔除的正常活髓人牙和24颗经过处理的无髓人牙中获取牙本质标本（n = 262）。这些标本经历了不同的实验条件（湿态、空气干燥、干燥和再水化）。进行压缩、间接拉伸和冲击试验以测量这些标本的力学性能。所有获得的数据都用t检验进行分析。结果表明，牙本质脱水会增加杨氏模量、比例极限（压缩时），尤其是极限强度（压缩和拉伸时）。大量脱水会改变牙本质标本在静态压缩和间接拉伸载荷下的断裂特性。未发现干燥牙本质的冲击破坏能量测量值有显著降低。本研究中获得的经过处理的无髓牙的牙本质的压缩强度和拉伸强度似乎与正常牙本质没有显著差异（p > 0.05），而压缩试验中杨氏模量和比例极限的平均值似乎较低。在压缩时，50%的经过处理的无髓牙的牙本质标本比正常牙本质表现出更大的塑性变形。本研究结果不支持牙髓治疗后脱水本身会在压缩强度和拉伸强度方面削弱牙本质结构的理论。然而，经过处理的无髓牙的其他力学性能可能与正常活髓牙不同。
