Objectives: the aim of this study was to find alternative technique to condition the dentine in order to reduce the degradation of the hybrid layer created with simplified dentine adhesives. Methods: flat dentine surfaces from extracted human third molars. A standard smear-layer was created with a 180-grit/SiC-paper. The dentine specimens were conditioned before bonding with the following criteria: 37%H₃PO₄ (15s); H₃PO₄ (15s)/0.5%NaOCl (25s); 0.1M EDTA (90s); 0.1M EDTA (90s)/0.5%NaOCl (25s). two etch-and-rinse adhesives: (Scotchbond 1 XT or Optibond Solo Plus) were then applied and light-cured. Composite build-ups were constructed (5-mm). The bonded teeth were sectioned into beams and stored under two conditions: distilled water (24h) or 14%NaOCl solution (90min). After storage the beams were tested for microtensile bond strengths (MTBS) and results were analyzed by ANOVA and Sidak's tests (p>0.05). Additional dentine surfaces were conditioned and bonded as previously described. They were prepared for pulpal-micropermeability confocal microscopy study, sectioned, polished and finally observed under TSM. Results: mean (SD) MTBS values (MPa) for each group are shown in the table: Same letter indicates no differences in row when maintained in the same storage media and same number indicates no differences in columns (p>0.05). Confocal micropermeability investigation showed very high permeability within interfaces of the group: H₃PO₄-etched dentine. The interface of the groups: H₃PO₄ + 0.5%NaOCl and 0.1M EDTA were less affected by micropermeability. Conclusions: the brief use of dilute NaOCl (0.5%) after acid-etching, or the conditioning of dentine smear layers with 0.1M EDTA (pH 7.4) allow the formation of a resin-dentine interfaces devoid of micropermeability. This alternative technique for dentine-conditioning improves the resistance of the bonds to harsh chemical treatment (14%NaOCl, pH 12). This may result in more durable resin-dentin bonds.

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