Airborne-particle abrasion with niobium phosphate bioactive glass on caries-affected dentin: effect on the microtensile bond strength

This study evaluated the effect of airborne-particle abrasion with niobium phosphate bioglass (NbG) microparticles on the bond strength (TBS) and longevity of an adhesive system to different dentin substrates. In this study, 18 Caries-free molars were used, of which 12 were microbiologically processed for caries induction. The dentin surfaces were evaluated in three groups: (1) Control - Healthy Dentin; (2) Partial removal of carious tissue; (3) complete removal of carious tissue. Half the teeth in each group were submitted to airborne-particle abrasion with NbG microparticles (15s/1cm/5bar). After this, the adhesive Clearfil S-3 was applied and composite buildups were constructed incrementally; and specimens were longitudinally sectioned to obtain bonded sticks (1.0 mm(2)) to be tested in tension (0.5 mm/min) immediately or after 6 months of storage in water. The fracture patterns were evaluated by stereomicroscope (40x) and then by scanning electron microscopy. The data were analyzed by the Kruskal-Wallis (post hoc Dunn) and Mann-Whitney tests (=0.05). Healthy dentin showed the highest bond strength (TBS). Airborne-particle abrasion with NbG increased the TBS values in the Group with complete caries removal. The bond strength values in the 24-h period were higher than those at 6 months. In the majority of the specimens the fracture mode was adhesive/mixed. The authors concluded that airborne-particle abrasion on dentin with NbG particles increased the TBS in the group in which carious dentin was completely removed.