Bonding of resin adhesives to caries-affected dentin – A systematic review

Minimal invasive dentistry aims at preserving the firm, discolored caries affected dentin (CAD), which is remineralizable. Research studies on resin adhesives are usually performed on sound dentin (SD), though CAD is the substrate routinely encountered for bonding in clinical practice. The aim of this paper was to systematically analyze the published literature on resin-dentin bonding to CAD substrate, in order to answer the question: “Does resin adhesive bonding to CAD produce lower bond strength when compared to SD?”. Three electronic databases (Pubmed, Scopus and ISI web of Science) were searched to identify original laboratory studies that evaluated the bond achieved between resin adhesive and natural CAD by measuring their bond strength. Only articles that met the specific inclusion criteria were included in the review. Among the 29 studies included for this review, majority of the studies had tested the simplified etch-and-rinse or self-etch adhesives. 85% of them showed higher bond strength to SD compared to CAD and the remaining 15% of them showed no difference between these two substrates. Among the studies that used 3-step etch-and-rinse adhesives, 40% showed higher and 60% showed no difference, when bond strength was compared between SD and CAD. Resin adhesives produce lower bond strength to caries-affected dentin than sound dentin. Research studies that reported bond strength of resin adhesives to dentin from sound extracted teeth alone cannot be blindly extrapolated to clinically relevant CAD. Hence, the results from such studies should be dealt with caution.