An ideal hybrid layer should have water and solvents completely replaced by resin monomers, thus creating an interdiffusion zone with collagen and resin, and guaranteeing resistance and adequate mechanical properties to resist the challenges incurred in restoration. Objective: To evaluate the influence of residual contamination by different concentrations of water, ethanol and chlorexidine on mechanical properties and conversion of two etch-and-rinse adhesives. Method: Bar specimens of a model

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... dhesive (M1) and a commercial Scotchbond MP adhesive (SBMP) were prepared and submitted to flexural strength (FS), elastic modulus (E), conversion degree (DC) and the kinetics of cure (K) evaluation. The real-time polymerization (RP) was monitored for 120 seconds. The data were statistically analyzed by two-way ANOVA and Tukey ś test (α=0.05). Results: All solutions showed a decrease in FS and E values. For M1 adhesive, this decrease could be noted with increase of all dilutions tested. A decrease in DC values also was noted as dilutions increased, independent of solution tested. For SBMP adhesive, the mechanical properties were affected more by water and chlorexidine solutions and, it was noted an increase in DC with the increase of solution, especially for ethanol. For K test, adding water to adhesives, a progressive decrease could be noted on graphics. Conclusions: So a reduction in mechanical properties of adhesive solutions could be noted when extreme amounts of residual solutions. Nevertheless, at lowest concentrations, ethanol and chlorexidine seems not interfere on K and RP of adhesives.