Abstract: Objective: To analyze the dynamics and fatigue failure mechanisms of the maxillary canine with normal or funnel-shaped root canal restored by fiber posts using the 3D finite element analysis. Methods: The eye tooth model of two root canals was obtained using the Micro CT scan and Mimics and UG software. The Nastran model was used to mimic the dynamic characteristics of the tooth. Smith-Waston-Topper principal was utilized to predict the fatigue life of the teeth, while the fatigue failure was also analyzed. Results: The fatigue resistance of the root canal with normal profile restored by the fiber posts was superior to that of the funnel-shaped root canal. The position of initial fatigue damage was similar to the position with the maximal principal stress. The threshold of the fatigue safety factors was coincidented with the transverse turning curve after repairment. In the presence of maximal strain, the line stretcher of the perpendicular line of the load was coincidented with the oblique turning curve after repairment. Conclusion: The shelf life of the root canal with normal profile was higher than that of the funnel-shaped root canal restored by the fiber posts. The localization of the maximal principal stress restored by fiber posts was the fatigue region susceptible to the injury. The fatigue failure was mainly induced by the fatigue structural damage and extension of the fatigue crack. The possibility of transverse and oblique fold was not the same under various conditions.

Key words: Fiber posts, Tooth dynamics, Shelf life prediction, Failure type