Fracture resistance of three post and core systems in endodontically treated teeth restored with all-ceramic crowns

The restoration of endodontically treated teeth requires the fabrication of a post and core to provide retention and support for the final crowns. The objective of this study was to compare the fracture resistance of endodontically treated teeth restored with glass fiber post and composite resin cores, customized zirconia posts, and cast metal post and cores. A total of 40 human extracted mandibular first premolars were used for the study. The teeth were randomly divided into four groups. Group A represented a control group that did not receive any posts and was filled with core material only; Group B comprised cast metal posts and cores; Group C comprised custom milled zirconia posts and cores; and Group D comprised glass fiber posts. All groups were prepared to receive all ceramic crowns. All samples were subjected to compressive testing with an Instron machine (Universal Testing Machine) and fracture loads and failure patterns were analyzed. The findings indicated a statistically significant difference between the failure loads in the groups studied. The mean load required to fracture the zirconia custom posts was higher (765.1 ± 48.5 N) than the fiber posts and the cast posts and cores (P < 0.001). The fiber posts resisted a mean load of 561.4 ± 37.2 N which was higher than the cast posts and cores. The control group revealed the lowest value of fracture resistance. Within the limitations of this study, it can be concluded that customized zirconia posts and cores resisted a higher mean load (765.1 + 48.5) when compared with other post and core systems. Failure patterns within this group revealed catastrophic failure, but the failure loads were much higher than the average occlusal load.