Adhesive resin systems have become increasingly popular as they have been demonstrated to infiltrate conditioned vital dentin to cohesively hybridize the biologically altered substrates for adhesive bonding. This paper is a review of the biologic and clinical use of Syntac (Ivoclar Vivadent) and Variolink (Ivoclar Vivadent) adhesive systems for cohesive hybridization of vital dentin to prevent patient postoperative hypersensitivity and bacterial microleakage following clinical preparation.