Influence of carbonate apatite nanoparticles incorporated into commercial dental adhesives on immediate and long-term microtensile bond strength.

This study assessed whether integrating carbonate apatite nanoparticles with a CO3/PO4 molar ratio of 5 (CA5n) into commercial adhesives affected the immediate or the long-term microtensile bond strength (µTBS) between composite resin and dentin. Scotchbond Multipurpose and Scotchbond Universal were tested with 0, 0.5, and 1 wt.% CA5n added. For Multipurpose, CA5n were incorporated into either the primer or the adhesive. Solutions were sonicated to minimize agglomeration. Sound human molars (n = 6/group) were prepared, and modified adhesives were applied as instructed. Composite was incrementally built up to 4 mm thick. Specimens were sectioned into beams and stored in water for 24 h or for 6 months before testing. Failure modes were observed. Data were analyzed using aligned rank transform anova (α < 0.05). CA5n had no impact on the bond strength of Multipurpose at either time point, irrespective of placement. Universal with 1% CA5n exhibited significantly higher 24 h µTBS than all other groups, but this advantage declined after 6 months. Mixed and adhesive failures increased over time, with the highest adhesive failure in Universal 1% at 6 months. Incorporation of CA5n into the tested adhesive systems did not significantly affect µTBS at 24 h or after 6 months of aging.