Effect of different artificial aging protocols on marginal sealing ability of self-etch dental adhesives: micro-computed tomography evaluation

The aim of this study was to investigate the sealing ability of different self-etch dental adhesives after different aging protocols. Sixty sound human third molars were used for this study. Two standardized Class II box cavities, with the gingival floor 1 mm below the cement-to-enamel junction were prepared in each tooth. Three adhesive groups (Clearfil SE Bond, Clearfil S3 Bond and Single Bond Universal) were subdivided into four subgroups (n = 10) according to the aging protocols: 24 h water storage (control); 1-year water aging; 10,000 thermocycling; and 240,000 thermo-mechanical aging. After the aging protocols, a 50% silver nitrate solution was used as a tracer. The internal adaptation analysis was performed using a micro computed tomography system. All tested aging protocols increase the silver nitrate penetration compared with the controls (p < 0.05). The samples aged in water have no significant difference with the samples aged with thermocycling (p > 0.05). The amount of silver nitrate penetration increased after thermo-mechanical aging for all samples (p < 0.05).The tested adhesives presented different marginal sealing abilities after thermo-mechanical loading and two-step self-etch adhesive showed lower silver nitrate penetration than one-step systems (p < 0.05).