Abstract: Abstract：　Objective　To evaluate effect of different decontaminations on bond strength of salivary contaminated dentin of primary teeth after light curing of the universal adhesive. Methods　Extracted human primary molars (60) were ground to mid-coronal dentin. The dentin specimens were randomly divided into 6 groups (n = 10/group/molar type) for a one-step universal adhesive (Single Bond Universal Adhesive): no saliva contamination (group A); saliva contamination after light curing of the adhesive followed by air drying (group B), rinsing with water spray/air drying (group C), direct reapplication of the adhesive and light curing (group D), air drying/reapplication of the adhesive and light curing(group E) or rinsing with water spray/air drying/reapplication of the adhesive and light curing(group F). Resin composite (Filtek Z250) was applied on the treated dentin surfaces. The specimens were stored at 37°C and 100% humidity for 24 h. After storage,micro-tensile strength(μTBS) and scanning electron microscope observation(SEM) was measured. Results　The μTBS of the group of E is the highest, and that of the group of D is the weakest. The fracture of the group of B、C and D is mostly at the bottom of mixed layer, and resin is not obvious. The fracture of the group of A、E and F is mostly at middle of mixed layer, and resin is obvious. Conclusions　When saliva contamination happened after light curing of the universal adhesive, the reapplication of the adhesive after cleaning the dentin surface was necessary for restoring the bond strength.

Key words: Universal Adhesive, Salivary contamination, Primary teeth, Micro-tensile strength