Methods: Thirty dentine crowns were etched using a 37%-H3PO4for 15s. The specimens were primed (Bis-GMA, PMDM, HEMA and 50wt%-ethanol) and bonded using three different adhesive systems: RCTRl (Bis-GMA, PMDM, and HEMA), RTCS (Bis-GMA, PMDM, HEMA and 40wt% tri-calcium-silicate) and RBAG (Bis-GMA, PMDM, HEMA and 40wt%Bioglass 45S5); light curing was performed for 20 s. 5mm incremental build-ups were made and photo-cured for 30 s. The μTBS results were compared statistically and the differences were identified among the groups by two-way ANOVA and Fisher’s least significant difference (LSD) tests (p < 0.05). Additional dentine surfaces were bonded as previously described. These were prepared, sectioned, polished and tested using KHN after 24 h and after 6 months of PBS storage. Confocal laser microscopy (CLSM) and SEM were employed to analyse the ultra-morphology (nanoleakage) of the resin-dentine interface and the fracture surface, respectively.
Results: The μTBS test showed high values after 24 h of PBS storage for both groups. However, only the experimental bonding agents containing the bioactive fillers maintained high μTBS and KHN values after 6 months of PBS storage. The CLSM showed mineral precipitation and nanoleakage reduction within the hybrid layer.
Conclusions: Dentine bonding agents containing calcium-silicate cement and Bioglass 45S5 as bioactive filler may be optimal candidates to improve the quality and longevity of resin-dentine interfaces.