Sodium Hypochlorite Treatment Post-Etching Improves the Bond Strength of Resin-Based Sealant to Hypomineralized Enamel by Removing Surface Organic Content

Purpose: he purpose of this study was to evaluate in vitro the effect of 5.25 percent sodium hypochlorite (NaOCl) on the bond strength of resin sealant to hypomineralized enamel. Methods: Sound (S) and hypomineralized (H) enamel specimens were subjected to three different treatments: (1) etch only (E); (2) 5.25 percent NaOCl treatment (60 seconds) after (Post) etching; and (3) 5.25 percent NaOCl treatment (60 seconds) before (Pre) etching. A sealant rod was bonded for microshear bond strength (mu SBS) testing. DIAGNOdent (TM) and spectrophotometry were used to detect changes in surface organic content and verify the amount of organic material removed. Results: Ninety S and 90 H specimens were randomly grouped into SE, SPost, SPre, HE, HPost, HPre groups. The average mu SBS of hypomineralized enamel in etch only (HE) and NaOCl pre-etch (HPre) were significantly lower (9.2 MPa). NaOCl after etching significantly increased the mu SBS of hypominineralized enamel (HPost) to 14.5 MPa, similar to sound enamel. DIAGNOdentT readings were significantly lower in NaOCl Post versus E and NaOCl Pre, suggesting lower surface organic content. Spectrophotometry confirmed that NaOCI significantly removed more organic material in hypomineralized enamel. Conclusion: Applying 5.25 percent sodium hypochlorite for 60 seconds after etching (32 percent phosphoric acid) increased the bond strength of resin sealant to hypomineralized enamel comparable to that of sound enamel, as a result of surface organic content removal.