Effects of adhesive temperature on the early and 6-month dentin bonding.

OBJECTIVES

The aim of this study was to test the effect of adhesive temperature on the bond strength to dentin (muTBS) and silver nitrate uptake (SNU) of an ethanol/water (Adper Single Bond 2 [SB]) and an acetone-based (Prime&Bond 2.1 [PB]) etch-and-rinse adhesive system.

METHODS

The bottles of each adhesive were kept in various temperatures (5 degrees C, 20 degrees C, 37 degrees C and 50 degrees C) for 1h previously to its application in the occlusal demineralized dentin of 40 molars. Bonded sticks (0.8 mm(2)) were tested in tension (0.5 mm/min) immediately (IM) or after 6 months (6 M) of water storage. Two bonded sticks from each hemi-tooth were immersed in silver nitrate and analyzed by SEM. Data were analyzed by two-way repeated measures ANOVA and Tukey's test (alpha=0.05).

RESULTS

No significant difference in muTBS was detected for both adhesives at 5 degrees C and 20 degrees C. The highest bond strength for PB was observed in the 37 degrees C group while for SB it was in the 50 degrees C. Significant reductions of bond strengths were observed for PB at 37 degrees C and SB at 50 degrees C after 6 M of water storage. Silver nitrate deposition was seen in all hybrid layers, irrespective of the group. Lower silver nitrate deposition (water trees) in the adhesive layer was seen for PB and SB at higher temperatures.

CONCLUSIONS

The heating or refrigeration of the adhesives did not improve their resin-dentin bond resistance to water degradation over time.