Flexural and Microtensile Bond Strength of Bulk Fill Materials.

ABSTRACT

AIM: The aim of this study was to evaluate the flexural and µTBS of bulk-fill materials. STUDY DESIGN: Bulk-fill materials SDR, X-trabase (XTR) and TetricEvoCeramBulkFill (EVO) were used in this study. To test flexural strength, 25x2x2mm samples were prepared and tested with three point bending test. To test the microtensile bond strength (µTBS), two blocks (4x4x4mm) were prepared for each material. In Group A+B, acid-etching was applied to the surface of one of these blocks and no acid-etching was applied in Group B. After applying bonding agent, two blocks were placed into the mold and composite resin (COMP; Tetric N-Ceram) was applied with incremental layering. To evaluate the µTBS of primary dentin, the bulk-fill materials were applied to flat dentin up to 4mm. The new blocks and the teeth were sectioned to obtain sticks and the sticks were loaded in tension until failure. Flexural and microtensile bond strength was calculated based on failure load. RESULTS: The ranking of materials with regards to flexural strength values were SDR>XTR>EVO>COMP,respectively. In GroupA+B, the µTBS values were XTR>SDR>EVO and were XTR>EVO>SDR in GroupB (p>0.05). The µTBS values of these materials to dentin were XTR>EVO>SDR (p>0.05). CONCLUSION: Within the limitations of this study, the use of a bonding agent without acid-etching showed positive interactions between base materials and composite resin and there were no significant differences in µTBS of these materials to dentin.