Longevity of bonds made by composite and polyacid-modified resins to dentin using a dual-cured adhesive system

To evaluate the microtensile bond strengths (MTBS) of a dual-cured dentin adhesive bonded to dentin using a light-cured resin-based composite (composite) or a polyacid-modified resin-based composite (compomer), and to investigate the effect of water aging on the bond strengths of these systems.

Flat dentin surfaces prepared from extracted human third molars were bonded with Prime&Bond NT Dual-Cured version (PBNT). Resin build-up crowns were constructed incrementally with two different materials: a composite (Z250) or a compomer (Dyract AP). When Dyract AP was used as the restorative material, half of the specimens were etched with 36% phosphoric acid, and the other half of the specimens were not etched. After storage in water for 24 hours or for 6 months, the teeth were sectioned to obtain bonded 1.3 mm2 beams containing the bonded interface. Each beam was tested in tension in an Instron machine at 0.5 mm/minute. Results were analyzed by multiple ANOVA and Student-Newman-Keuls multiple comparison tests.

The group PBNT/Dyract AP bonded to acid-etched dentin showed the highest bond strength, in the 24-hour evaluation. Bond strength values decreased significantly after aging. The groups treated with PBNT in light-cured, dual-cured and self-cured modes performed equally well in the 24-hour evaluation. After 6 months of water aging, bond-strengths of the light-cured groups remained stable. By contrast, decreases in the bond strengths of the self-cured groups were observed.