Abstract
Effect of smear layer on bonding to dentin prepared with either a steel or a diamond bur-was studied.A half of the prepared dentins was pretreated with an aqueous solution of 20% 2-methacryloyloxyethyl phenyl hydrogen phosphate(Phenyl-P)and 30% 2-hydroxyethyl methacrylate(HEMA)for 60s, and then a photocure bonding agent, 5% Phenyl-P in triethyleneglycol dimethacrylate(TEGDMA)was primed.The other half was conditioned with 10-3 for 10s to remove the smear and 4-META/MMA-TBB was bonded to the surface.The tensile bond strength to the smear-retained dentin was lower(5-8MPa)because the tensile strength of the hybrid layer prepared by burs or ground with #180 paper was too weak to reinforce with the impregnated resin.On the other hand, that of the latter to the smear-removed dentin was 14MPa.These conclusions were drawn through SEM examinations of the fractured surface due to tensile load and cross-sections and through TEM examination of the hybrid layer.The dentin cavity prepared with burs must be improved to condition to obtain reliable bonding with an adhesive.
