Bonding is the key to adhesive dentistry* which has profoundly altered the capabilities and treatment options of restorative dentistry. The ability of restorative resins to form a micro-mechanical bond to teeth requires careful surface preparation which is different for enamel and dentin. Once those surfaces have been cleaned and etched, adhesive resins can lock into the intricate surface irregularities that have been exposed.
*1949: The first system of bonding acrylic resin to dentin (Hagger)
1955: The discovery of tenacious attachment of acrylic resin to acid etched enamel (Buonocore)
1978: Visible light curing of restorative resins