Evaluation of physicochemical and antibacterial properties of an experimental adhesive resin containing casein phosphopeptide-amorphous calcium phosphate.

This study aimed to evaluate the polymerization, contact angle, surface tension, antibacterial activity, and bonding properties of experimental adhesives modified with the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP). A conventional universal adhesive resin was modified by incorporating CPP-ACP at different concentrations by weight (1% and 3%), resulting in experimental adhesive resin groups. The groups were classified as Control (without CPP-ACP), 1% CPP-ACP, and 3% CPP-ACP. The microshear bond strength (µSBS) to enamel and dentin, monomer conversion degree (DC), antibacterial activity against S. mutans and L. casei, contact angle, and surface tension were evaluated. The antibacterial activity of the materials was assessed using the agar diffusion method. The obtained data were statistically analyzed, and a significance level of p < 0.05 was considered. When comparing the DCs of the adhesive resins, no statistically significant difference was found between the Control group, 1% CPP-ACP, and 3% CPP-ACP groups (p > 0.05). However, a statistically significant difference was observed between the 1% CPP-ACP and 3% CPP-ACP groups (p < 0.05). According to the µSBS test results, no significant difference was observed in the µSBS values related to the tooth substrates (enamel and dentin) (p > 0.05). When comparing the µSBS to dentin, a statistically significant difference was found between the 1% CPP-ACP group and the other groups (p < 0.05), while no significant difference was found between the Control and 3% CPP-ACP groups (p > 0.05). Regarding the µSBS to enamel, only a significant difference was found between the Control group and the 3% CPP-ACP group (p < 0.05). When evaluating the antibacterial activity of the adhesive resins against S. mutans, an increase in antibacterial activity was observed with the increasing CPP-ACP concentration (p < 0.05). No antibacterial activity was observed against L. Casei. According to the contact angle and surface tension test results, no statistically significant difference was observed between the groups (p > 0.05). The incorporation of CPP-ACP into the universal adhesive resin influenced bonding performance in a concentration- and substrate-dependent manner, with 1% CPP-ACP enhancing dentin bond strength and 3% CPP-ACP improving enamel bonding. Clinical Significance: CPP-ACP-modified adhesives demonstrated substrate-specific benefits, with 1% CPP-ACP enhancing bond strength to dentin and 3% CPP-ACP improving adhesion to enamel. These findings suggest that tailored CPP-ACP concentrations may optimize bonding performance while providing antibacterial effects, without compromising the fundamental properties of the adhesive system.