Design and Fatigue Evaluation of Parameters for Crack Detection: An in Vitro Study
Understanding fatigue is important to the success of dental materials as evident from the eventual failure of restorations and cyclic loads during mastication. However, detection of such failures often poses clinical challenges as most cracks are invisible or subsurface when initiated and only identified when catastrophic failures occur. Current detection methods are limited in clinical application. Therefore, the aim of this research study was to design a test method and parameters that simulate the oral environment to assess the detection of crack initiation and growth using quantitative percussion diagnostics (QPD) technology. Nine 3D tooth models were subjected to cyclic fatigue loading amplitudes of 92 N accompanied by periodic QPD testing. Normal fit error values determined by QPD before loading and after fatigue cycling testing were recorded for the 3D simulated teeth. Results showed that location and depth of notch were important determinants of the number of cycles to crack initiation. The QPD device was able to monitor crack initiation and growth in at least three of the simulated teeth with accuracy. Although each tooth was found to reach failure at a different cycle number, the paired comparison was non-significant (p= 0.099) indicating results are comparable. Future analysis requires more simulated teeth to confirm these findings. Also, a comparison of the data obtained from 3D tooth models to natural extracted teeth as well as comparison to existing diagnostic tools used for crack identification would be warranted. These preliminary findings provide further evidence for the use of QPD as a diagnostic aid for early crack identification and monitoring structural integrity of teeth.