The effect of post material on the characteristic strength of fatigued endodontically treated teeth

Statement of problem The biomechanical properties of post systems may become more important as the amount of remaining tooth structure decreases, thus different materials may influence the characteristic strength of fatigued endodontically treated teeth. Purpose The purpose of this study was to assess the characteristic strength and probability of survival of endodontically treated teeth restored with different intraradicular post systems. Material and methods Forty human maxillary canines with similar root lengths were randomly divided into 4 groups (n=10): cast post and core, stainless-steel prefabricated post, carbon-fiber post, and glass-fiber post. Cores and metallic crowns were fabricated for all specimens. Restored teeth were exposed to mechanical fatigue (250 000 cycles) in a controlled chewing simulator. Each intact specimen was mounted in a special device and aligned at a 45-degree angle to the long axis of the tooth. A universal testing machine was used to apply a static load at a crosshead speed of 0.5 mm/min until specimen failure. The maximum value was recorded in newtons (N). Probability Weibull curves (2-sided 90% confidence bounds) were calculated for each group, and a probability of survival as a function of load at failure was plotted for the groups. Results A significantly higher characteristic strength was observed for groups carbon-fiber post (755.82 N) and cast post and core (750.6 N) ( P