The effect of sodium hypochlorite on microleakage of composite resin restorations using three adhesive systems.

PURPOSE The aim of this study was to evaluate the effect of three different adhesive systems on microleakage of Class V restorations after the use of sodium hypochlorite. MATERIALS AND METHODS One-hundred eighty bovine incisors were selected and randomly divided into 9 groups (n = 20): G1: Single Bond (SB); G2: 10% NaOCl solution (NS) + SB; G3: 10% NaOCl gel (NG) + SB; G4: Prime & Bond NT (PB); G5: NS + PB; G6: NG + PB; G7: Gluma One Bond (GOB); G8: NS + GOB; G9: NG + GOB. Standardized Class V cavities were prepared. All teeth were etched with 37% phosphoric acid for 15 s. In groups 2, 5, and 8, a 10% NaOCl solution was applied for 60 s to the dentin, and in groups 3, 6, and 9, a 10% NaOCl gel was applied to dentin for 60 s. All cavities were restored with composite resin Definite. The specimens were thermocycled for 1000 cycles (5 degrees C to 55 degrees C) and then immersed in 2% buffered solution of methylene blue for 4 h. The specimens were sectioned and analyzed according to a ranking score (0 to 4). Kruskal-Wallis and Mann-Whitney non-parametric tests (p < or = 0.05) were used for statistical analysis. RESULTS The NaOCl treatment significantly increased microleakage at the dentin margin (p = 0.0129) as shown by the following sums of ranks: G1 = 1008.0a; G4 = 1301.5ab; G3 = 1687.0ab; G7 = 1744.0bc; G2 = 1802.0c; G9 = 1880.0c; G5 = 1889.0c; G8 = 1950.0c; G6 = 1963.0c (different superscripts indicate significant differences). For enamel, there were no statistically significant differences among the groups (p > 0.05). CONCLUSION Depending on the adhesive system used, the application of NaOCl increased microleakage along dentin margins.