EFFECTS OF DENTIN SURFACE TREATMENTS ON THE FRACTURE-TOUGHNESS AND TENSILE BOND STRENGTH OF A DENTIN-COMPOSITE ADHESIVE INTERFACE

It has been proposed that the fracture toughness test provides an appr opriate method for assessing the fracture resistance of the dentin-com posite interface. The plane-strain fracture toughness test was therefo re applied to a dentin-composite interface, with use of a specific den tinal adhesive, so that the effects of various dentin surface treatmen ts on dentin-bond integrity could be studied. Interfacial fracture tou ghness (K-IC) values were determined following 24 h and 180 days of sp ecimen aging in distilled water at 37 degrees C. Tensile bond strength (TBS) results following 24-hour aging were also obtained for comparis on with the 24-hour K-IC results. In general, the fracture resistance of the dentin-composite interface was highest when the dentin surface was conditioned with acid but not air-dried, intermediate when the den tin surface was conditioned with acid and subsequently air-dried, and lowest when the dentin was not conditioned with acid. The tensile bond strength results differed from the fracture toughness results in indi cating differences in surface preparation effects and the type of inte rfacial failure observed.