[Effect of bonding agents in the degree of microleakage around posterior composite resin restorations].

The purpose of this in vitro study was to examine, by the dye technique, the microleakage pattern of two posterior composite resin materials, alone or combined with three commercially available dentin bonding agents. Composite resins used were P-30 (3M) and Heliomolar (Vivadent). The bonding agents were Gluma (Bayer), Scotch-bond LC (3M) and Dentin Adhesit (Vivadent). MOD cavities were prepared on extracted posterior teeth with a 330 tungsten carbide bur, in an airtor handpiece. The gingival floor of the mesial surface was located in the enamel above the CEJ and the distal gingival floor in the cementum below the CEJ. Specimens were thermocycled between 4 degrees and 60 degrees C for fifty cycles of two minutes each and imbibed for 10 hours in a 2% basic fuchsin solution and split in two halves. According to the results we obtained we came to the conclusion that: Both composite resins exhibited significant microleakage when they were used alone, without bonding agent. The gingival floor of the mesial surface (located in the enamel) exhibited in most specimens, less microleakage than the distal one. The use of bonding agents decreased but not eliminated the microleakage at the gingival floor of the cavities.