Statement of the problem: Eugenol is a radical scavenger that inhibits the polymerization of resin materials. Little is known about the effect of a eugenol-containing temporary restorative material on the resin-dentin bond strength of adhesive systems that partially dissolves and modifies the smear layer.
Purpose of the study: The aim of this study was to evaluate the effect of eugenol-containing temporary restoration (zinc oxide eugenol [ZOE]) on the resin-dentin microshear bond strength of etch-and-rinse and self-etch adhesives.
Material and methods: The roots of 18 human molars were removed and the crowns of the teeth were transversally sectioned into two halves. The dentin surfaces were embedded in acrylic resin. Half of the samples were stored while the remaining specimens were restored with eugenol-containing temporary restoration. After 24 hours, the ZOE restoration was mechanically removed and dentin surfaces were ultrasonically cleaned. Dentin surfaces were treated with one of the following adhesives: Single Bond, Clearfil SE, and iBond. Six cylinders of Z250 (0.5 mm high and 0.75 mm in diameter) were applied to each bonded dentin surface using a tygon tube. After storage for 24 hours, the specimens were subjected to micro-shear testing. The data was subjected to a two-way analysis of variance and Tukey's test (alpha=0.05).
Results: Similar bond strength values were obtained for Single Bond (p=0.48) either in the control or in the ZOE-treated group. For both self-etch systems, the bond strength in the ZOE-treated group was statistically lower than the control group (p < 0.01).
Conclusions: Although the prior use of eugenol-containing temporary restoration (IRM) affects the resin-dentin bond strength of the etch-and-rinse Single Bond, a more pronounced reduction on bond strength was observed for the two self-etch systems evaluated (iBond, Clearfil SE Bond). CLINICAL SIGNIFICANCE Eugenol-containing provisional restorations (IRM) should not be used prior to the placement of resin restorations bonded with the two-step etch-and-rinse Single Bond and the self-etch adhesives systems iBond and Clearfil SE Bond.