Objective: To evaluate the effect of bulk-fill restorative techniques on microleakage and fracture resistance of endodontically treated teeth.
Material and Methods: Eighty maxillary second premolars were selected and randomly divided into four groups (n=20). All teeth received class II cavity preparations followed by endodontic treatment. In Group I, 4mm of flowable bulk-fill material (Tetric EvoFlow Bulk Fill - TEFBF) were applied then overlaid with bulk-fill restorative resin (Tetric EvoCeram Bulk Fill - TECBF). In Group II, only Bulk Fill restorative resin (TECBF) was used to restore the entire preparation. In Group III: 1mm of conventional nanohybrid flowable composite (Tetric EvoFlow - TEF) was applied then overlaid with conventional nanohybrid composite (Tetric EvoCeram - TEC) using incremental layering technique. In Group IV, only conventional nanohybrid composite (TEV) with incremental layering was used. All specimens were then subjected to a thermocycling regimen. Microleakage was evaluated on half of the specimens by dye penetration at the tooth restoration interface. The remaining specimens were subjected to fracture resistance testing under occlusal load and the results analyzed using Kruskal-Wallis and Mann-Whitney U tests, with significance set at p=0.05.
Results: Specimens in Groups I and III showed dye penetration reaching the depth of the axial walls while none was observed in Groups II and IV. Groups I and II showed significantly higher fracture strength compared to groups III and IV.
Conclusion: 1- The use of bulk-fill restorative technique improved the fracture strength of endodontically treated teeth. 2- The use of bulk fill resin did not affect the cervical microleakage of restorations. 3- Both bulk fill resin and conventional nanohybrid resin restorations have greater tendency for cervical microleakage when flowable resin is used underneath them.