Aim: This in vitro study aimed to evaluate the effect of dentin surface-treatment with 4mg/ml Galla Chinensis Extract (GCE) on microtensile bond strength and nanoleakage of a resin composite restoration, subjected to two different water storage periods.
Materials and Methods: A total of thirty freshly extracted sound human molars were prepared and sliced coronally for application of a nanohybrid resin composite restorative material (Filtek Z350 XT). Exposed dentin surfaces, were acid-etched, to be either routinely covered by adhesive and resin composite, or treated with 4mg/ml Galla Chinensis Extract, followed by application of an adhesive and a resin composite. Treated teeth were divided into 3 subgroups according to time of assessment of their microtensile bond strength and nanoleakage after 24 hours, 3 months and 6 months of water storage.
Data were statistically analyzed with One-way ANOVA at 95% confidence interval. Kolmogorov Smirnov and Shapiro-Wilk tests were applied for normality testing. Independent t-test was used to compare between different groups for different water storage periods.
Results: Insignificantly different microtensile bond strength values between control and surface-treated teeth were recorded for the resin composite material immediately and after 3 months water storage periods. Lowest values were recorded after 6 months storage period, differing significantly (p ≤0.001) between control and surface-treated dentin group. The immediately tested control group revealed significantly the highest mean microtensile bond strength values (32.1±7.84 MPa) compared to both other control groups at different storage periods. SEM micrographs showed extensive silver deposition throughout the entire hybrid layer thickness of silver-impregnated sections at resin/dentin interfaces after 6 months aging period. These depositions penetrated into dentinal tubules and around the resin tags in the control group.
Conclusions: Surface treatment of etched dentin with 4mg/ml Galla Chinensis Extract improved resistance of bonded resin composite restorations to hydrolysis in terms of improved microtensile bond strength and nanoleakage after 3and 6 months of water storage.