Effect of exposure time of zinc oxide eugenol restoration on microtensile bond strength of adhesives to dentin

Abstract

ObjectiveThe purpose of this study was to evaluate the influence of different exposure times (24h, 7 days and 45 days) of zinc oxide eugenol cement (ZOE) on microtensile bond strength (μTBS) of etch-and-rinse and self-etch adhesives. MethodsOcclusal enamel of 40 human molars was removed. Zinc oxide eugenol restoration was placed on the dentin surface and left for different times (24h, 7 days or 45 days). After ZOE removal or over fresh dentin (control) were restored using Adper Single Bond 2 (SB2) or Clearfil S3 Bond (CS3). After 24h, each tooth was longitudinally sectioned, to obtain bonded sticks that were tested under tension (0.5mm/min). Two-way ANOVA and Tukey's test (α=0.05) were used to compare μTBS. ResultsA decrease in μTBS was observed for SB2 after 24h (46.8±3.4MPa) when compared to the control (60.4±5.2MPa, p<0.05). Similarly, a decrease was observed for CS3 after storage for 24h (20.4±2.2MPa) and 7 days (18.1±2.1MPa), when compared with a control group (39.1±4.2MPa, p<0.05). After 45 days, both adhesives SB2 and CS3 show the same μTBS compared to controls. Under all conditions, SB2 showed higher μTBS values than CS3 (p<0.001). ConclusionThe results suggest that ZOE has negative effects on microtensile bond strength after 24h.