title: Mechanism of adhesion of polymers to acid-etched enamel. Effect of acid concentration and washing on bond strength.
abstract: The tensile bond strengths of composites to enamel etched with various concentrations of phosphoric acid have been shown to correlate closely with the phase diagram for the system Ca(OH)2/H3PO4/H2O. Bond strengths were independent of the adhesive used and were a maximum when using approximately 20% phosphoric acid as etchant. High bond strengths were obtained with 2% phosphoric acid etchant without 'tag' formation, after short term water immersion. Washing the enamel for 60 s instead of 15 s after etching significantly increased the bond strengths obtained with 16 and 30% acid but not with 2%. Etching enamel with phosphoric acid results in deposition of calcium phosphates, which must be removed to give optimal bonding.
mesh_terms: D000134:Acid Etching, Dental; D000268:Adhesiveness; D002130:Calcium Phosphates; D003188:Composite Resins; D001840:Dental Bonding; D003743:Dental Enamel / Q000187:drug effects / Q000648:ultrastructure*; D010756:Phosphoric Acids / Q000494:pharmacology; D013499:Surface Properties; D013718:Tensile Strength; D014867:Water
chemical_list: D002130:Calcium Phosphates; D003188:Composite Resins; D010756:Phosphoric Acids; D014867:Water