Shear Bond Strength and Physicochemical Interactions of XP Bond

Purpose: The purpose of this study was to evaluate the shear bond strength of composite to dentin and enamel using the new etch-and-rinse adhesive XP Bond compared to other adhesives (OptiBond Solo Plus, Adper Scotchbond 1 XT, Syntac Classic). Materials and Methods: Shear bond strength (MPa) was measured by shearing a resin cylinder 4.5 mm in diameter from prepared buccal surfaces of human third molars using an Instron Testing Machine equipped with a chiselshaped rod. In addition, micro-Raman spectroscopy was performed to determine if there was a chemical interaction between the resin adhesive and dentin and enamel. Results: Significant differences were observed among the dentin and enamel values generated with the adhesives tested. XP Bond generated statistically similar values to Optibond Solo Plus and Adper Scotchbond 1 XT to both enamel and dentin. Syntac Classic generated significantly lower values to both enamel and dentin. Conclusion: Micro-Raman spectroscopy showed a complete infiltration of resin into the demineralized dentin zone. In addition, it strongly suggested a chemical interaction with XP Bond and components of dentin. It is hypothesized that this interaction is due to the formation of calcium phosphate complexes derived from mineral apatite in the dentin and phosphate esters in the adhesive. Keywords: adhesion, bonding, chemical analysis, Raman spectroscopy