Active application improves the bonding performance of self-etch adhesives to dentin.

Objectives: To evaluate the effect of application method on immediate and 6-month resin-dentin microtensile bond strength (microTBS) and nanoleakage (NL) of three one-step self-etch adhesives systems (Clearfil S(3) Bond (S3), Xeno III (XE) and Adper Prompt L-Pop (AD)).

Methods: The oclusal enamel of 30 human molar was removed in order to expose a flat dentin surface. The adhesives were applied under two modes: inactive (IN) or active (AC) application. After light-curing (600mW/cm2 for 10s), composite buildups were constructed incrementally and sectioned to obtain bonded sticks (0.8mm2) to be tested in tension immediately (IM) or after 6 months (6M) of water storage. For NL, three bonded sticks from each tooth at each time were coated with nail varnish, placed in silver nitrate and polished down with SiC paper. The microTBS data were submitted to a two-way ANOVA and Tukey's test for each adhesive (alpha=0.05).

Results: The AC showed higher microTBS to dentin when compared to IN in both periods of time (p=0.001). Only for AD, lower microTBS was seen after 6M for IN and AC techniques. XE and S3 adhesives applied under IN showed a higher amount of silver penetration throughout the hybrid layer. Low silver nitrate deposition was seen for these adhesives under AC. After 6M, AD showed a higher amount of silver nitrate uptake under IN and AC techniques.

Conclusions: AC improves the bonding performance of all one-step self-etch adhesive systems tested regardless of the time and this tendency was maintained over time.