Evaluation of the Fracture Behavior of Severely Damaged Endodontically Treated Anterior Teeth with Different Core Systems.

Background: The purpose of this in vitro study was to determine the fracture behavior of severely damaged anterior endodontically treated teeth with a core buildup and polyethylene ribbon fiber in different orientations. Material and Methods: Forty human maxillary incisors that had been endodontically treated were prepared to receive a core buildup and divided into 4 groups (n=10): glass fiber post, polyethylene ribbon fiber inserted horizontally, polyethylene ribbon fiber inserted vertically, and core only. The cores were made with short fiber resin composite. The teeth were statically loaded on the palatal surface until fracture, and the failure mode was classified. The mean values of the groups were analyzed by using the Shapiro-Wilk test and 1-way analysis of variance (=.05). Results: The highest fracture loads were observed in the polyethylene ribbon groups: vertical insertion (677.6 ± 2.4 N) and horizontal insertion (657.1 ± 2.2 N). These were followed by the glass fiber post (421.5 ± 2.2 N) and the core-only group (246.3 ± 4.0 N). The polyethylene ribbon fiber groups were statistically similar (p>0.05). The greatest mean maximum strain, stress, and fracture strength were obtained by the core buildup with polyethylene ribbon fiber inserted horizontally. No significant difference in the fracture strength and maximum stress was found among the glass fiber post, core only, and polyethylene ribbon fiber groups inserted vertically groups (p>0.05). The ratio of catastrophic to non-catastrophic failure was similar for the polyethylene ribbon fiber groups (both 50% - 50%) and for the glass-fiber post (60% - 40%) and core only (70% - 30%). Conclusions: Cores made with short fiber resin composite with polyethylene ribbon fiber inserted vertically or horizontally can be used as an alternative to conventional post systems.