Methods: Twelve dentin discs were obtained from twelve human caries free molars. Adhesive system [Futurabond U (Voco) and Scotchbond Universal Adhesive System (3M ESPE)] was applied according manufacturers’ instructions (n=3), as a self-etching or an etch-&-rinse system. Discs were restored with GrandioSO Flow resin (Voco) and sectioned with a precision saw (IsoMet1000-Buehler), in order to obtain sticks with a cross section of 0.8±0.2 mm². The specimens were processed to TEM analysis and observed under an analytical TEM (Hitachi H7650), with an accelerating voltage of 100KV.
Results: TEM analysis revealed a thicker resin-dentin interdiffusionzone for etch-&-rinse than self-etch protocol, in both adhesive systems. Hydroxyapatite crystallites and some individual collagen fibers were observed within the hybrid layer.
Conclusion: The resin-dentin interdiffusion zones created by both adhesive systems had similar thickness and morphology. (This work was performed at UICOB, R&D unit nº 4062 of FCT).