Concepts of adhesion--a review.

This paper reviews the current concepts of adhesion in restorative dentistry. Despite the numerous products available in the market, adhesion occurs in one or a combination of four ways. 1. Acid-etch and formation of resin tags. 2. Formation of strongly bonded surface precipitates, to which a resin can be chemically or mechanically bonded. 3. Chemical bonding to the inorganic components of tooth structure. 4. Chemical bonding to the organic components of tooth structure. With the success of the acid-etch technique for bonding to enamel, much of today's adhesive research has been directed towards bonding to dentine. None of the currently available dentine adhesives can achieve an ideal bond to dentine.