Purpose: The purpose of this study was to assess in vitro the effect of etching time on tensile bond strength to primary dentin.
Methods: Forty crowns of sound primary molars were embedded in acrylic resin (N=40). Dentin was exposed in the buccal surfaces, and the specimens were randomly assigned into 4 groups (N=10), according to the etching time with 35% phosphoric acid gel: G1=7 seconds; G2=10 seconds; G3=15 seconds; G4=20 seconds. A 3-mm diameter bonding site was demarcated, the adhesive system was applied, and resin composite cones were built up. After 24 hours, tensile bond strength tests were performed. Data were submitted to statistical analysis using one-way analysis of variance and the Tukey test.
Results: Means (+/-SD) were (MPa): (1) G1=10.04 (+/-3.30); (2) G2=7.78 (+/-4,49); (3) G3=8.78 (+/-2.96); (4) G4=7.60 (+/-1.91).
Conclusions: Although no statistically significant difference among the times used was found, the 7-second etching time promoted the highest bond strength mean and can be used in primary dentin. Additionally, this lower etching time reduces chair time, which is a significant benefit when treating children.