Incorporation of proanthocyanidin into dental adhesive on resin dentine bonding

Abstract

OBJECTIVE: This study evaluated the effect of proanthocyanidin (PA) incorporation into experimental dental adhesives on resin-dentine bond strength and dentine pulp complex. METHODS: The experimental adhesive was first formulated by combining 50 wt% comonomer mixtures with 50 wt% ethanol. Proanthocyanidin was then added directly to the ethanol-solvated experimental adhesives to yield concentrations of 1.0 wt%, 2.0 wt% and 3.0 wt%. The PA-free experimental adhesive served as the control. Prepared dentine surfaces from extracted third molars were bonded using the experimental adhesives and divided into 4 groups and proceed for microtensile bond strength testing after 24 hrs in artificial saliva. Additional bonded specimens were prepared for nanoleakage analysis under FE-SEM, nano-indentation and SEM/EDX analysis. RESULTS: No significant difference in dentine bond strength was found among proanthocyanidin-free, 1% and 2% proanthocyanidin-incorporated dental adhesives (P>0.05). Conversely, incorporation of 3% proanthocyanidin into dental adhesives significantly lowered dentine bond strength with increased percentage of adhesive failure and nanoleakge at the bonded interface (P<0.05). The 2% PA incorporated adhesive has shown to increase the nanohardness and modulus of elasticity of the hybrid layer (P<0.05). Calcium and Phosphate ratio has significantly increased in the hybrid layer infiltrated with 2% PA incorporated adhesive (P<0.05).Conclusion: Incorporation of 2% proanthocyanidin into dental adhesives had no adverse effect on resin-dentine bond strength and has shown to increase the nanomechanical properties of the hybrid layer.