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Purpose: The aim of this study was to investigate the effect of saliva contamination on bond strength of an etch-and-rinse system to dentin. Methods: Fifty bovine incisors were embedded in acrylic resin and divided into 5 groups: G1 (control) - application of the adhesive system (Adper Single Bond 2 - 3M-ESPE); G2 - saliva contamination after acid etching of dentin, rinsing and drying; G3 - saliva contamination after acid etching of dentin and drying; G4 - saliva contamination after adhesive application, rinsing and drying; G5 - saliva contamination after adhesive application and drying. Contamination was performed by using 4 [mu]L of simulated human saliva for 20 s. The adhesive system was applied according to the manufacturer's instructions; a composite resin was built as an inverted cone and was tested after 24 h at a cross-head speed of 0.5 mm/min. Results: When saliva contamination occurred after the adhesive photo-polymerization, bond strength was significantly reduced. The adhesive strength (MPa) mean values were: G1 = 18.1(±4.7) a; G2 = 20.5(±5.7) a; G3 = 17.3(±3.4) a; G4 = 12.6(±4.0) b; G5 = 9.8(±2.1) b (means followed by distinct letters are statistically different, P < 0.05). Conclusion: Saliva contamination negatively influenced bond strength of an etch-and-rinse adhesive, especially after the final polymerization of the adhesive system; in this condition, treatments were not efficient to recover adhesion. [ABSTRACT FROM AUTHOR]