UC Irvine

As we all know, teeth are typical brittle fracture material; there will be no apparent signs or painful experiences for patients to be aware of before the crack becomes challenging to control and restore. In addition, conventional dental diagnostics aids are partially effective in diagnosing structural defects such as cracks in teeth. Therefore, a new detection method, Quantitative Percussion Diagnostics, usually used to test the structure’s instability, seems like a good choice for doctors to detect the crack before it goes to an irreversible status. But the natural cracked tooth samples are hard to test and analyze to get the actual cracks status of the tooth since the extraction processes produce additional cracks. In addition, most crack growth of the natural teeth is vertical downward, so if we directly fatigue the intact replica tooth, there’s no way to get regular, consistent crack. Therefore, a method of printing a notched 3D replica tooth using a glass-filled resin polymer with mechanical properties similar to dentin was established. After fatiguing on a specific machine, the replica teeth containing such a simulated fatigue crack were tested using Quantitative Percussion Diagnostics (QPD). The results were consistent with QPD data for cracked natural teeth. Besides, the NanoCT scanning results reveal that our methodology can form a short but sharp vertical crack extending from the notch tip. It can be helpful for future research to connect the QPD test results and the internal crack status in a natural tooth.