Effects of a Peripheral Enamel Margin on the Long-term Bond Strength and Nanoleakage of Composite/Dentin Interfaces Produced by Self-adhesive and Conventional Resin Cements

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Purpose: This study evaluated the effects of peripheral enamel margins on the long-term bond strength (mu TBS) and nanoleakage in resin/dentin interfaces produced by self-adhesive and conventional resin cements. Materials and Methods: Five self-adhesive [RelyX-Unicem (UN), RelyX-U100 (UC), GCem (GC), Maxcem (MC), Set (SET)] and 2 conventional resin cements [RelyX-ARC(RX), Panavia F(PF)] were used. An additional group included the use of a two-step self-etching adhesive (SE Bond) with Panavia F (PS). One hundred ninety-two molars were assigned to 8 groups according to luting material. Five-mm-thick composite disks were cemented and assigned to 3 subgroups according to water-exposure condition (n = 6): 24-h peripheral exposure (24h-PE-enamel margins), or 1 year of peripheral (1yr-PE) or direct exposure (1yr-DE-dentin margin). Restored teeth were sectioned into beams and tested in tension at 1 mm/min. Data were analyzed by two-way ANOVA and Tukey's test. Two additional specimens in each group were prepared for nanoleakage evaluation. Nanoleakage patterns were observed under SEM/TEM. Results: Except for RX, no significant reduction in mu TBS was observed between 24h-PE and 1yr-PE. 1yr-DE reduced mu TBS for RX, PF, GC, MC, and SET. No significant reduction in mu TBS was observed for PS, UC, and UN after 1 year. After 1yr-DE, RX and PS presented the highest mu TBS, and SET and MC the lowest. Nanoleakage was reduced when there was a peripheral enamel margin. SET and MC presented more silver deposition than other groups. Conclusion: The presence of a peripheral enamel margin reduced the degradation rate in resin/dentin interfaces for most materials. The mu TBS values produced by the multi-step luting agents RX and PS were significantly higher than those observed for self-adhesive cement143251263Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2007/06083-4, 2007/06447-6