The effects of acid etching on the pulpodentin complex.

Acid etching of dentin is used by many bonding systems to remove the smear layer and permit bonding directly to the dentin matrix. Although early animal studies indicated that acid etching caused moderate to severe pulpal reactions, there is a high probability that the pulpal irritation may have been due to microleakage of bacteria and their products. As these reactions are not seen following acid etching of dentin using newer dentin bonding systems, it is clear that one can acid etch dentin if, and only if, one can seal the dentin with subsequently placed bonding systems. Because acid etching increases dentin permeability and dentin wetness, successful bonding of adhesive resins to acid-etched dentin requires the use of hydrophilic resins that bond equally well to both peritubular and intratubular dentin. Future trends seem to be toward lowering both the concentration of acids and the time of etching of dentin. While all bonding systems should be carefully scrutinized prior to marketing, the future looks very promising for the use of adhesive resins on acid-etched dentin.