Effect of load cycling on nanoleakage of butt joint and beveled occlusal enamel margins in class V composite resin restorations / Efeito do ciclo de carga na nanoinfi ltração de margens de esmalte oclusal com e sem bisel em restaurações classe V

ABSTRACT

Objectives: This study evaluated the infl uence of mechanical and thermal cycling on the nanoleakageof Class V composite resin restorations with and without enamel beveling. Material and method:Using 60 Class V cavities prepared on the buccal surfaces of human molars, specimens were dividedinto two groups (n = 30) based on the confi gurations of the enamel cavosurface margins. (beveled andnon-beveled) After restoring the cavity preparations with a fl owable composite, half of the specimenswere mechanically load-cycled. The specimens were sealed leaving a 1 mm window around the cervicaland enamel margins. Specimens were placed in a 50% (W/V) silver nitrate solution then immersedin photodeveloping solution and exposed to fl uorescent light for 8h. The teeth were buccolinguallysectioned, gold sputter coated and examined with a SEM to evaluate the nanoleakage values. The datawere analyzed using two-way ANOVA (α = 0.05). Results: Enamel margin confi guration had no significant effect on nanoleakage (p > 0.05). However, the nanoleakage value was signifi cantly higher inthe load-cycled group than in the group not load-cycled (p < 0.05). Conclusion: Since enamel margin confi guration does not affect nanoleakage, there is no need to bevel enamel margins of Class V cavitypreparations for composite restorations.