Effect of Aging on Microtensile Bond Strength of Prime and Bond NT to Dentin

Objectives: To compare microtensile bond strength (MTBS) of different commercial versions of the adhesive Prime and Bond NT (PBNT) to dentin after aging. Methods: Extracted human third molars had their crowns transversally sectioned to exposed flat dentin surfaces. The surfaces were bonded with three PBNT versions light-cure, self-cure and dual cure, according to directions. Resin build-up crowns (6 mm height) were constructed incrementally (1.5 mm) with two different materials Z250 resin composite or Dyract. PBNT was bonded without previous acid-etching of dentin when Dyract was used as restorative. After 24 hours and 6 months storage in water at 37 ºC, the teeth were sectioned in both “x” and “y” directions to obtain several bonded sticks of 1.0 mm² of cross-sectional area. Each stick was tested in tension in an Instron machine at 0.5 mm/min. Results were analysed by ANOVA and SNK tests (α=0.05). Results: In MPa (SD). Letters indicate statistical differences in columns and numbers in files.

Conclusions: After 24 h storage PBNT self attained the highest MTBS values but decreased after aging. Except for PBNT self, Z250 and Dyract performed equally. Storage time did not affect MTBS of PBNT light.(CICYT/FEDER: Grant # MAT2001-2843-C02;RED CYTED VIII.J).