Characterization and Antibacterial Effect of an Experimental Adhesive Containing Different Concentrations of Proanthocyanidin

Purpose: To evaluate the degree of conversion (DC%), water sorption (Sp), solubility (Sl), dentin bond strength (μTBS) (immediate and after 12 months of storage), and the antibacterial effect of an experimental adhesive containing different concentrations (%) of proanthocyanidin (PA): 0, 1%, 2%, 4.5%, and 6% (PA0, PA1%, PA2%, PA4.5% and PA6%, respectively). Materials and Methods: DC% was measured by FT-IR and the Sp and Sl were determined based on the ISO 4049 specification. For μTBS, resin composite buildups were constructed incrementally and specimens (n = 8) were sectioned to obtain sticks (1 mm2). The μTBS was evaluated after 24 h and 12 months of water storage at 37°C. The failure mode was analyzed. The antibacterial effects were evaluated by analyzing the bacterial growth (S. mutans) (n = 5) and antibiofilm activity (n = 5) of the adhesives by spectrophotometry. Results: The incorporation of PA did not affect the Sp, Sl, or DC%. Immediate μTBS was similar for all groups. After 12 months, PA4.5% presented significantly higher μTBS than PA0, while the other groups did not differ from PA0 and PA4.5%. Groups PA0 and PA1% underwent significant reduction in μTBS. In the experimental groups PA2%, PA4.5% and PA6%, μTBS was maintained after storage. All groups showed antibacterial activity. Conclusion: Incorporation of 2%, 4.5%, and 6% PA maintained the dentin μTBS after 12-month storage, without affecting the Sp, Sl, or DC% of experimental adhesives. PA4.5% presented higher μTBS values than PA0 after 12 months. The adhesive presented antibacterial effect irrespective of PA concentration. Parole chiave: dentin bonding agents, cross linker, antimicrobial, bond strength