Long-term bond strengths to dentin treated with different re-wetting solutions

To evaluate the microtensile bond strengths (microTBS) of two etch-and-rinse one-bottle adhesive systems to air-dried dentin re-wet with different agents.

48 bovine teeth were ground flat to 600-grit and were assigned for treatment with either Single Bond or One-Step adhesives. Each group had three subgroups of re-wetting agents: water, Gluma Desensitizer and Aqua-Prep F. The teeth were acid-etched, air-dried for 5 seconds and re-wet with water, Gluma Desensitizer or Aqua-Prep F for 30 seconds and blot dried. Control specimens were prepared using a moist bonding technique. The adhesives were applied and the teeth were restored with Filtek Z250 or Renew composite. After 24 hours in distilled water at 37 degrees C, the teeth were sectioned into 0.7 mm-thick slabs, trimmed, and immediately tested for microTBS or stored for 6 months or 1 year prior to testing. Fracture sites were examined under scanning electron microscope (SEM). Data were evaluated by one- and three-way ANOVA, and Fisher's PLSD test (P<0.05).

Except for Aqua-Prep F, the microTBS in the control, water and Gluma Desensitizer subgroups did not change significantly after 1-year for both Single Bond and One-Step groups. SEM analysis showed no specific pattern of fracture in the Single Bond specimens. One-Step had the majority of the fractures at the interface at baseline, and becoming a mixture of fractures at the interface and within the adhesive resin after 1 year.