Effect of NaOCl as Canal Irrigant on Microleakage of Resin Composite Restorations

Sodium hypochlorite is used as an endodontic irrigant for different purposes. Since it is a strong oxidizing agent it might inhibit the resin polymerization. The objective of this in vitro study was to compare the effect of NaOCl on sealing ability of total etch and self etch bonding at different time intervals after root canal therapy. The roof of the pulp chambers and roots (1-2 mm below furcation) of eighty human first molar teeth were cut and pulp tissues were completely removed. Teeth were divided in two groups (n=40), based on the type of used adhsive; total etch (Scotchbond Multi-Purpose plus) and self etch (Clearfil SE Bond). Immediately, chamber pulp of ten teeth of each group were restored with resin composite (control groups). Thirty teeth in each group were treated with 5% NaOCl for 5 minutes in the chamber pulp and restored with resin composite associated with each bonding agent (Z100, Clearfil Photo Core) in three intervals: immediately, one, and two weeks after irrigation with NaOCl. Fluid filtration method was used for evaluation of microleakage. Data were statistically analyzed using ANOVA and T-test (α =.05). Type of dentin adhesive and different time intervals after NaOCl application and restoration, did not show any significant effect on microleakage value (p>0.05). The variable of using and not using of NaOCl showed significant difference on microleakage value (p<0.05). NaOCl treated samples demonstrated significantly higher microleakage. Irrigation with NaOCl during root canal therapy has a negative effect on microleakage of resin composite restorations. Delayed time for restoration did not remove the negative effect of NaOCl.