Effect of different bonded base materials on the fracture resistance and failure mode of complex cavity of endodontically treated premolars. (An in Vitro Study)

Objectives: Objective: The aim of this study was to evaluate the effect of different bonded base materials on fracture resistance of endodontically with complex cavities, and the assessment of the mode and type of fracture of each experimental group. Materials and Methods: Fifty freshly extracted, intact, non-carious human maxillary second premolar teeth with similar anatomic characteristics were selected, the teeth were classified according to their mesiodistal and buccolingual dimensions into five groups. Endodontic treatment performed for all the groups except Group 1 Group 1 intact teeth (control group). Group 2 unrestored teeth with endodontic treatment. Group 3 endodontically treated as in group 2 and restored with (smart dentine replacement) SDR bulk-fill. Group 4 restored with Vertise flow self-adhering flowable composite with optibond technology. Group 5 endodontically treated as in group 2 and restored with GC EQUIA Fill. The cavities in group 3,4 and five were then filled with Filtek Z250XT composite. Fracture resistance testing: All specimens were subjected to axial compressive loading until fracture in Hydraulic Universal Testing Machine (WDW 2006, China). The f