Laboratory studies that evaluated the bond

Dentin-bonded interfaces achieved with contemporary resin adhesives have shown to degrade with time [19] and [20], due to hydrolytic degradation of adhesive resin as one of the major reasons that results from an increased concentration of BMH-21 monomers [21] and [22]. As resin–dentin bonded interfaces show degradation with time, it becomes important to achieve a high initial bond strength so that the bonded interfaces could withstand the degradation process over time. This is another reason for why it is necessary to compare the bond strength achieved by resin adhesives between sound dentin and CAD. If the initial resin-CAD bond strength is lower than the resin-sound dentin bond strength, then obviously the degradation process will lead to greater reduction in bond strength to CAD eventually. Also, as the dentin carious process involves MMP and cysteine cathepsins activities [23], the degradation could be more pronounced in such a substrate compared to sound dentin.