Method: Twelve dentin discs were obtained from twelve human caries-free molars. As multimode adhesive systems [Futurabond U (Voco) and Scotchbond Universal Adhesive System (3M ESPE)] were used in self-etch or etch and rinse mode. Four experimental groups were set (n=3). Specimens were restored with GrandioSO Flow resin (Voco) and sectioned with a precision saw (IsoMet 1000-Buehler), in order to obtain sticks with a cross section of 0.8±0.2 mm2. After coated with two layers of fast setting nail varnish applied 1 mm from the bonded interfaces, the sticks were immersed in ammoniacal silver nitrate (50%wt; pH=9.5) for 24h and placed in photodeveloping solution for 8h under a fluorescent light. Silver penetration at adhesive interface was examined with TEM (Hitachi H7650), with an accelerating voltage of 100KV.
Results: TEM revealed no nanoleakage on the self-etching groups, but silver was detected when the adhesive systems were used in etch-&-rinse mode. No nanoleakage differences were found between the adhesives studied.
Conclusion: The adhesive systems tested in self-etch mode revealed a homogeneous resin-dentin interdiffusionzone, with no relevant nanoleakage at 24h. (This work was performed at UICOB, R&D unit nº 4062 of FCT).