Análise da resistência de união, nanoinfiltração e características ultramorfológicas das interfaces de união resina-dentina produzidas por cimentos auto-adesivos ao longo do tempo.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2010

RESUMO

This study evaluated the effects of a peripheral enamel bond on the long-term microtensile bond strength (μTBS) and nanoleakage in resin-dentin interfaces produced by self-adhesive and conventional resin cements. Five self-adhesive cements [RelyX-Unicem(UN), RelyX-U100(UC), GCem(GC), Maxcem(MC), Set(SET)] and 2 conventional resin cements, one that uses a 2-step etch-and-rinse adhesive [RelyX-ARC(RX)], and one that uses a 1-step self-etching adhesive [Panavia-F(PF)] were used. An additional group included the use of a 2-step selfetching primer system (Clearfil SE Bond) with Panavia F(PS). 192 human molars were assigned to 8 groups according to the luting material (144 for the μTBS test and 48 for the electron microscopy analysis). Five-mm thick composite discs (Z250) were cemented according to manufacturers instructions, and were assigned to 3 subgroups, according to the degree of water-exposure(n=6): 24h of peripheral water exposure (24h-PE (enamel margins); and 1 year of peripheral exposure (1yr-PE) or direct exposure (1yr-DE - dentin margin). After storage periods restored teeth were sectioned into beams and tested in tension. Data were analyzed by two-way ANOVA and Tukey test. Two additional specimens per group were subjected to a silver impregnation protocol and nanoleakage patterns were observed under an SEM or TEM. Except for RX, no significant reduction in μTBS was observed between 24h-PE and 1yr-PE. 1yr-DE reduced μTBS for RX, PF, GC, MC and SET. No significant reduction in μTBS was observed for PS, UC and UN after 1 year. After 1yr-DE, RX and PS presented the highest μTBS values, and SET and MC, the lowest. Nanoleakage was reduced for most of the resin cements when there was a peripheral enamel margin. SET and MC presented more silver deposition than other groups. The presence of a peripheral enamel bond seemed to reduce the degradation rate in resin-dentin interfaces for most materials. The bond strengths produced by the multi-step luting agents RX and PS were significantly higher than those observed for self-adhesive cements.

ASSUNTO(S)

self-adhesive cements, resin cements, tem, sem, nanoleakage, microtensile bond strength. cimentos auto-adesivos, cimentos resinosos, met, mev, nanoinfiltração, resistência e união, microtração. odontologia

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