Effects of endodontic and restorative treatments on teeth damping ratio

Objectives: Clinical observations indicated that teeth accepted endodontic and restorative treatments would result in higher prevalence of fracture. However, the mechanism of such phenomenon is still unclear. The aim of this study was to detect the effects of endodontic and restorative treatments on tooth damping properties, as well as its stress dispersion capability. Methods: Extracted maxillary first premolars, due to orthodontic treatment, were used as test subjects. The teeth were clamped on a metal stand to simulate a fully fixed boundary condition. Then, the teeth were subjected to a series of endodontic and restorative treatments. Four treated steps were performed throughout the experiments. In the first step (test group I), cleaning and shaping of the canals were performed. Then, the teeth were treated with root canal filling (RCF) and 2 mm caviton was filled in the occlusal area (test group II). In the group III, the caviton in the test teeth were replaced with composite resin. Finally, the teeth received post-and-crown restoration (test group IV). During the four treatment procedures, as well as original status (test group V), damping ratios of the teeth were detected by modal testing technique. The changes in damping ratio between the five test groups were compared and discussed. Results: Our results indicated that the mean damping ratio of the group I teeth (8.76±0.52%) was significantly lower than the teeth without any treatment (14.80±2.67%, p<0.05). However, the damping ratio of the teeth reduced significantly (p<0.05) after post-and-crown treatment (8.82±0.52%). Conclusion: Our findings demonstrated that filling material has effects on the damping properties of restored teeth. Accordingly, it is reasonable to suggest that selection of adequate filling materials is an important issue for a successful treatment.