Effect of Smear Layer Deproteinization on Gingival Marginal Sealing of Self-Adhesive Flowable Composites: A Micro-CT Study.

UNLABELLED: Self-adhesive flowable resin composites have been developed to simplify restorative procedures by eliminating separate adhesive application; however, their gingival sealing to dentin remains a concern. This study assessed the gingival marginal sealing of resin composites by measuring silver nitrate solution (AgNO3) penetration using micro-computed tomography (µCT). MATERIALS AND METHODS: Seventy-five human third molars with 150 standardized cavities were allocated into 15 experimental groups based on three surface pretreatments (no pretreatment, sodium hypochlorite solution [NaOCl], and a hypochlorous acid-containing aqueous solution [HCS]) and five restorative materials: three self-adhesive flowable composites (Fusio Self-Adhesive, Vertise Flow, and Nova Compo SF) and two conventional composites (Clearfil Majesty Posterior and Clearfil Majesty Flow). Following thermal cycling, microleakage was quantified by measuring silver nitrate penetration along the gingival floor of the restorations using µCT and statistically analyzed. RESULTS: HCS significantly reduced silver nitrate penetration in all self-adhesive composites (p < 0.05), while NaOCl significantly reduced silver nitrate penetration only in the 10-MDP-containing Nova Compo SF (p < 0.05). Conventional composites bonded with a self-etch adhesive exhibited significantly lower microleakage than self-adhesive materials (p < 0.05). CONCLUSIONS: HCS improved the gingival marginal sealing of self-adhesive flowable composites to dentin, whereas the effect of NaOCl was material-dependent. Conventional resin composites used with a self-etch adhesive demonstrated superior gingival marginal sealing compared with self-adhesive flowable composites.