Fracture resistance of endodontically treated teeth restored with bulk fill, bulk fill flowable, fiber-reinforced, and conventional resin composite

The aim of this in vitro study was to evaluate the fracture resistance of endodontically treated teeth restored with different types of restorative resins. Methods and Materials: Seventy-two sound maxillary premolar teeth were randomly divided into six groups (n=12). The teeth in the first group were left intact and tested as unprepared negative control (group I) specimens. The teeth in the remaining five groups were prepared with MOD cavities and endodontically treated. The teeth in one of the five groups (positive control group II) were unrestored. The rest of the prepared cavities were restored as follows: group III: bulk fill resin composite/Filtek Bulk Fill (3M ESPE); group IV: bulk fill flowable resin composite + nanohybrid/SureFil SDR Flow + Ceram.X Mono (Dentsply); group V: fiber-reinforced composite + posterior resin composite/GC everX posterior + G-aenial posterior (GC Corp.); and group VI: nanohybrid resin composite/Tetric N-Ceram (Ivoclar/Vivadent). Each restorative material was used with its respective adhesive system. The restored teeth were stored in distilled water for 24 hours at 378C and were then thermocycled (5- 558C, 10003). Specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The data were analyzed using one-way analysis of variance followed by the post hoc Tukey honestly significantly different test (p<0.05). Results: Sound premolar teeth (group I negative control) showed significantly higher fracture resistance than did the other tested groups (p<0.05). No statistically significant differences were found in the fracture resistance values of the restored groups (groups III, IV, V, and VI) (p>0.05). The lowest values were obtained in the positive control group (group II); these values were significantly lower than those of the other groups (p<0.05). Conclusion: The fracture resistance values of endodontically treated teeth restored with either bulk fill/bulk fill flowable or fiber-reinforced composite were not different from those restored with conventional nanohybrid resin composite.