Effect of Various Surface Treatments on Micromorphology of MTA Plus® and Biodentine® and Comparative Evaluation of Their Shear Bond Strength to Composite Resin- an invitro SEM analysis

Introduction: To evaluate the micromorphological changes due to different surface treatments on MTA Plus® and Biodentine® and comparison of their shear bond strength to composite resin with three different adhesive systems. Methods: Eighty acrylic blocks with a standardized central hole were prepared and filled with MTA Plus (Group A) and Biodentine (Group B). They were randomly divided into four subgroups each; A1, B1: Control groups (untreated samples); A2, B2: One-step self- etch adhesive; A3, B3: Two-step self-etch adhesive; A4, B4: Two-step etch and rinse adhesive. Surface treatment was performed using phosphoric acid or self-etch primer, and untreated surfaces were used as controls. The surface changes were observed under a scanning electron microscope. The specimens were bonded with the respective adhesive systems followed by composite resin restoration. The shear bond strength was tested using universal testing machine and the data was subjected to one-way ANOVA and Tukey's multiple comparison test. Results: Extensive loss of globular structure was seen in phosphoric acid treated group while only selective loss was observed in samples treated with self-etch primer. Treated surfaces of MTA Plus showed more internal pores and cracks as compared to treated Biodentine surfaces. The one-step self-etch adhesive system showed significantly higher shear bond strength when compared with other groups (p< 0.05). MTA Plus exhibited better shear bond strength as compared to Biodentine, which was statistically non-significant (p>0.05). Conclusions: Either surface treatments cause alteration in micromorphology of MTA- Plus and Biodentine. One-step self-etch adhesives could be a preferred choice when bonding composite to Biodentine or MTA Plus.