Comparative evaluation of shear bond strength of a dual-cure core build-up composite bonded to dentin using three different self-etch dentin bonding systems - An in-vitro study

Aim: This in-vitro study compared the shear bond strength of a dual-cure core build-up composite bonded to dentin using a two-step self-etch adhesive, with two, single step self-etch universal adhesive systems. Materials and Methods: In the present in-vitro study, sixty extracted permanent human mandibular molar teeth, decoronated below the dentino-enamel junction to expose the coronal dentin, were taken and later mounted in self-cure acrylic resin. The specimens were randomly divided into three groups of twenty samples each, based on the dentin bonding agents used namely ParaBond (a two-step self-etch adhesive) and two one-step universal adhesives i.e. Single Bond Universal and Tetric N-Bond Universal. The dentin surface of samples was treated with the respective adhesives of the groups according to manufacturer's instructions. The bonded surface was bulk filled using ParaCore dual-cure composite. The attained samples were stored in distilled water at 370C for 24hrs and subsequently put through thermocycling (50C to 550C for 500 cycles). The samples were than subjected to shear loading in Instron Universal testing machine. The data were tabulated and statistically analyzed using analysis of variance (ANOVA) and Tukey's HSD test. Results: Tetric N-Bond Universal adhesive showed the highest mean Shear Bond Strength (SBS) of 20.78 MPa, followed by Single Bond Universal 19.07 MPa and ParaBond Adhesive 5.44 MPa. Conclusion: Tetric N-Bond Universal showed the highest mean SBS and a predictable relationship was found between the formulation of dentin adhesive systems and their shear bond strength values. Clinical Significance: The universal adhesives showed high shear bond strength as compared to conventional 2-step self-etch adhesives. High acidic pH of self-etch adhesive affected their bond strength. So for stake of bond stability, a mild self-etch / universal adhesive is recommended for adhesion, because higher the bond strength, higher it can withstand the stress resulting in a successful restoration.