Abstract
The dentin bonding durability of a total-etch adhesive system (Prime & Bond® NT) was investigated by tensile bond test using conventional and dumbbell-shaped specimens. Two bonding techniques were compared. After etching and rinsing, dentin surface was either blotted by cotton ball (wet-bonding) or air-dried (dry-bonding) before bonding agent was applied. The bond strength of wet-bonding specimens was significantly higher than that of dry-bonding for both conventional and dumbbell-shaped specimens after one day. The bond strength of wet-bonded conventional specimens did not decrease after two years of water immersion, but cohesive failure in demineralized dentin was observed after two years. Wet-bonded dumbbell-shaped specimens showed cohesive failure within demineralized dentin after only one day. The bond strength of drybonded conventional specimens decreased significantly after one year, and cohesive failure in demineralized dentin was confirmed after three months. As for dry-bonded dumbbell-shaped specimens, they showed cohesive failure in demineralized dentin after one month. The results of the present study showed that the bonding durability of dry-bonded Prime & Bond® NT restorations was lower than that of wet-bonded restorations. Further, by using tensile bond test, cohesive failure in demineralized dentin was detected earlier in dumbbell-shaped specimens than in conventional specimens.
