Adhesive application before hydrofluoric acid etching during repair procedure in dentistry?

Purpose To evaluate the influence of hydrofluoric acid (HF) contamination on the microtensile bond strength (μTBS) during dental repair procedures before and after application of different dentin adhesives (Optibond FL and Optibond XTR). Materials and methods Thirty-five human molars were ground down into the dentin and were randomly divided into seven groups (G1-G7; n = 5), G1 and G2 being the control groups. Only in the test groups (G3-G7) samples were subjected to HF (9,5%) contamination. Two adhesive systems, Optibond FL (G1, G3, G4, G6) and Optibond XTR (G2, G5, G7) were used. In G3-G5 the adhesive was applied before and after contamination, the test groups G6 and G7 were treated with a single adhesive application after contamination. After composite build-up, samples were stored in water (7 d) and μTBS was determined. Data were evaluated using Wilcoxon test (p < 0.05). Results Control group G2 showed significantly higher μTBS than G1. The HF-contamination did not result in a significant reduction of μTBS. The μTBS of the test groups treated with OptiBond XTR (G5, G7) were significantly higher than the test groups treated with OptiBond FL (G3, G4, G6) following the same procedure. Conclusions HF-contamination of dentin or the adhesive layer does not significantly impair the bond strength, if the adhesive is subsequently re-applied.