Bond strength and adhesive interfacial micromorphology of self-adhesive resin cements: Effect of reduced times of pre-etching

Abstract

Background: Although acid-etching could increase enamel bond strength of self-adhesive (SA) cements, it may lead to negative effect on dentin. The aim of this study was to assess the effect of shortening of phosphoric acid pre-etching duration on enamel/ dentin shear bond strength (SBS) and interfacial microstructure of Panavia SA Luting Plus (PASA) and Bifix SE (BXSE). Material and Methods: A flat enamel/dentin surfaces of extracted molars were prepared and each substrate was divided into two SA cements groups and each was subdivided into four groups (n=12) according to time of acid pre-etching as follows: 1) Non-etch, 2) 5-second pre-etching, 3) 10-second pre-etching, 4) 15-second pre-etching. Following 7-day storage of cemented specimens, SBS was tested. Data for each cement were separately analyzed using two-way ANOVA and Tukey test (α=0.05). An additional specimen from each group was prepared for field emission scanning electron microscope (Fe-SEM) observation. Results: For both enamel and dentin, effect of pre-etching time was significant (p<0.001); however, effect of cement brand and the interaction of two factors was significant only for dentin (p≤0.008). Three pre-etching times increased SBS of both cements to enamel and BXSE to dentin. In case of dentin SBS of PASA, this improvement was significant only for 5 and 10 seconds (p<0.001). Adding acid-etching in the three times to both cements similarly improved interfacial adaptation, particularly for enamel. Conclusions: Interfacial bond strength and adaptation of SA cements used in this study were improved following addition of enamel/dentin etching step for a short time. This was not exceeded for longer times than 5-second.