A Novel Chemical Ageing for Evaluating Dentin Bond Durability

Method: The cusps of 48 human third molars were cut off to expose the mid-crown dentin. The dentin surfaces were applied with one of five dentin adhesive systems strictly according to the manufacturers’ instructions and subsequently, placed with the respective composite-resins from the same manufacturer (Clearfil S3 Bond+Clearfil Majesty, Clearfil SE Bond+Clearfil Majesty, Kuraray Co.; Adper Easy One+Z250, Adper Single Bond 2+Z250, 3M ESPE; Gluma Comfort Bond+Charisma, Hereaus Kurzer). After the specimens were sectioned longitudinally through the resin-dentin interfaces, they were prepared into beams with a cross-sectional area of 1mm². The beams were kept in water for 24h serving as control, or in 10wt% NaOH solution at 37°C for 2, 4, 6, 12h respectively. After storage, micro-tensile bond tests were performed and representative fractured surfaces were examined by scanning electron microscopy (SEM). In addition, the resin-dentin interfaces were observed by SEM. The data were analyzed by two-way ANOVA(p<0.05).

Result: With the extension of storage time in NaOH solution, all the dentin MTBS significantly decreased (p<0.05), and the numbers and the sizes of the micro-gaps at the resin-dentin interface significantly increased.

Conclusion: Storage in NaOH solution might be a novel chemical ageing for evaluating dentin bond durability.