Purpose: To evaluate the effect of the etching strategy on the immediate and 1-year microtensile bond strength (μTBS) and structural reliability of a universal adhesive to sound and artificially-induced caries-affected dentin of primary teeth. Materials and Methods: Flat midcoronal dentin surfaces were exposed in 50 primary molars, which were then randomly assigned to 10 groups according to substrate (sound dentin [SD] and artificially-induced caries-affected dentin [CAD] with pH cycling for 14 days) and etching approach using Scotchbond Universal Adhesive (self-etching or dry or wet-bonding etch-and-rinse strategies) with Adper Single Bond Plus (two-step etch-and-rinse adhesive) and Clearfil SE Bond (two-step self-etching system) as controls. Composite buildups were constructed and sectioned to obtain bonded sticks (0.8 mm2) to be subjected to microtensile testing immediately or after 1 year of water aging. Data were analyzed using three-way repeated measures ANOVA and Tukey's test (α = 0.05). Weibull modulus and characteristic strength were also determined. Results: A decrease in bond strength was observed after 1 year of water aging, except when the universal adhesive was used in the dry-bonding etch-and-rinse and self-etching approaches. However, the self-etching approach resulted in lower μTBS values in SD, while no difference among experimental groups was observed in CAD. Overall, higher Weibull modulus values were achieved in the groups with higher bond strength. The relationship between characteristic strength and bond strengths was not linear for all groups. Conclusion: The bond longevity of the universal adhesive using the dry-bonding etch-and-rinse approach on sound and artificially-induced caries-affected primary dentin was better than the other bonding agents and approaches tested. Keywords: multimode adhesive, structural reliability, caries-affected dentin, deciduous tooth, durability, microtensile