Etching enamel with phosphoric acid will provide the highest bond strength. However, when bonding to dentin, phosphoric acid is not necessary. Self-etching dentin will mildly alter the smear layer, incorporating it to the bonding layer, which can reduce the possibility of post- operative sensitivity and protect the pulp-dentin complex. In addition, the activation of MMPs may be minimized. Therefore, if a clinician wants to obtain a durable and predictable bond to both enamel and dentin, selective-etching is the recommended protocol because it will provide the most predictable and durable bond to both enamel (using phosphoric acid etch) and dentin.