Effect of Sodium Hypochlorite on Microleakage of Single Bond and One Step Bonding Agents

Effective bond to dental substrate and good marginal adaptation at the tooth/restoration interface are important in clinical success of restorations. Microleakage is the most important factor responsible for marginal staining, development of secondary caries, pulpal damage and eventual failure of composite restorations. The aim of this study was to evaluate the effect of sodium hypochlorite on microleakage of two step total etch bonding agents with different solvents. Also, the effect of replacement of phosphoric acid with sodium hypochlorite on microleakage was evaluated.
This in vitro experimental study was conducted on 80 sound bovine incisors. Eighty class V cavities were prepared on buccal surfaces of the teeth. The occlusal and cervical margins were prepared in the enamel. Then, the samples were randomly divided into eight groups (n=10). After bonding, the cavities were restored with Z250 composite. After finishing and polishing, the specimens were thermocycled for 1000 cycles between 5-55C and immersed in 2% aqueous solution of basic fuchsin for 24 hours. Then, they were sectioned longitudinally and analyzed for microleakage under a stereomicroscope. Microleakage was evaluated and compared among the groups using the Kruskal-Wallis test and two-way ANOVA.
Rate of microleakage was the highest in acid sodium hypochlorite and the lowest in sodium hypochlorite acid groups. Significant differences existed between the two bonding agents except for sodium hypochlorite acid. The highest and lowest microleakage in acid sodium hypochlorite were noted in One Step and Single Bond, respectively. In use of sodium hypochlorite alone, microleakage was not significantly different between the two groups. Single Bond had the highest microleakage in the control group. The interaction effect of preparation method and type of bonding agent was significant as well (P=0.001).
Application of sodium hypochlorite before dentin etching increased microleakage in use of One Step bonding agent compared to etching alone. However, its use after etching in use of Single Bond improved the seal.