Effect of dentin moisture and storage time on resin bonding.

PURPOSE

To evaluate the effects of dentin moisture and two different storage times on the shear bond strength of resin composite bonded to dentin with Scotchbond Multi-Purpose Adhesive.

MATERIALS AND METHODS

The occlusal surfaces of 60 extracted human molars were reduced to provide flat dentin surfaces. After being hand-finished using wet 400- and 600-grit SiC papers, the teeth were randomly divided into four groups of 15 specimens each. The teeth were etched, rinsed, and then either blotted with gauze which left a visibly moist surface or dried with compressed air. The primer and adhesive were applied according to the manufacturer's instructions and resin composite cylinders were bonded to the teeth. Two of the groups (one moist, one dry) were stored for 24 hours in 37 degrees C distilled water while the other two groups were stored for 90 days in 37 degrees C distilled water. At the end of their storage times, the specimens were loaded to failure in shear at 0.5 mm/minute.

RESULTS

Mean bond strength values and standard deviations in MPa were: Dry dentin at 24 hrs, 13.30 +/- 5.1; Dry dentin at 90 days, 13.07 +/- 3.8; Moist dentin at 24 hours, 13.64 +/- 4.9; Moist dentin at 90 days, 15.58 +/- 5.3. No statistically significant differences were found for bond strengths to dry and to moist dentin for either storage time. Time had no significant effect for either the dry dentin group or the moist dentin group.