A Determination of the Cyclic Fatigue Crack Growth Properties of Human Teeth

9900296 Arola牙科清洁在维护终身口腔健康方面发挥着不可或缺的作用。 因此，由于再发生的蛀牙、边缘差异和牙齿断裂而导致的牙齿矫正失败是具有实质性临床意义的主题。 本研究的目的是证明牙齿中的循环疲劳裂纹扩展是导致牙齿修复失败的一种重要且基本上未被认识的机制。 待测试的假设是，牙齿中的疲劳裂纹生长始于使用牙科布尔斯进行牙洞制备期间引入的缺陷，并由包括标准口腔活动的循环机械和热负荷驱动。 裂纹扩展直至达到临界裂纹长度，这使得生物牙齿结构丧失或修复体整体断裂。 在这项研究中，在人类牙本质的循环裂纹扩展速率和裂纹长度阈值将确定从四点弯曲牙本质标本进行的实验分析。 将使用数控切片机/研磨机从人牙制备疲劳样本。 通过施加模式I循环压缩，在零至最大四点弯曲疲劳载荷之前，将在每个样本中引入预疲劳裂纹。 由弯曲载荷引起的循环裂纹扩展速率将根据瞬时裂纹长度和最大循环弯曲应力进行量化。 使用从实验分析中获得的累积疲劳裂纹扩展数据，将确定根据巴黎定律描述循环疲劳裂纹扩展的参数。 从实验研究的结果将确定的意义，在洞制备过程中引入的修复牙齿的疲劳寿命的表面下的缺陷。

9900296ArolaDental restorations play an integral role in the maintenance of lifelongoral health. Consequently, the failure of dental restorations through reoccurring tooth decay, marginal discrepancies, and tooth fracture, are topics of substantial clinical significance. The objective of the research is to show that cyclic fatigue crack growth in teeth is an important and largely unrecognized mechanism that contributes to dental restoration failure. The hypothesis to be tested that that fatigue crack growth in teeth initiates at flaws introduced during cavity preparation with dental burs and is driven by cyclic mechanical and thermal loads which encompass standard oral activity. The flaw propagates until reaching a critical crack length which enables the loss of biological tooth structure or bulk fracture of the restoration. In this study the cyclic crack growth rate in human dentin and the threshold crack length will be determined from an experimental analysis conducted with four-point-bend dentin specimens. Fatigue specimens will be prepared from human teeth using a numerically controlled slicer/grinder. A pre-fatigue crack will be introduced in each specimen, prior to zero-to-maximum four point bend fatigue loading, through the application of Mode I cyclic compression. The cyclic flaw growth rate resulting from bend loading will be quantified in terms of the instantaneous crack length and maximum cyclic bend stress. Using the cumulative fatigue crack growth data obtained from experimental analysis, the parameters describing cyclic fatigue crack growth according to the Paris Law will be determined. Results from the experimental study will identify the significance of subsurface flaws introduced during cavity preparation on the fatigue life of restored teeth.