Influence of tooth age and application time on the microtensile bond strengths of different adhesive systems to dentin

This study evaluated the effect of tooth age and application time on the microtensile bond strengths (μTBS) of different adhesives to dentin. One-hundred twenty intact human teeth were mechanically ground to expose mid-coronal dentin and randomized to three groups (n=40) according to subject’s age in years: 15-25, 35-45, and ≥55. Within each group, specimens were further randomized to 8 experimental subgroups according to adhesive (etch-and-rinse 3- and 2-step; selfetch 2- and 1-step) and application time (instructions vs. extended). Composite resin was applied to the treated surfaces and after storage for 24 hours all specimens were processed for μTBS testing. Data were analyzed by factorial ANOVA and post-hoc tests (p=0.05). μTBS values ranged from 10.9 MPa (2-step self-etch, extended application time, age group 15-25) to 50.7 MPa (1-step self-etch, extended application time, age group ≥55). Tooth age and application time had no significant effect on μTBS of the adhesives tested