University Archives

As secondary caries remains a prevalent shortcoming of permanent dental restorations, the capability of restorative materials to protect dental hard tissues against demineralization through ion release and acid neutralization represents a viable mechanism to extend the service life of restorations. Several new bioactive composite materials were recently introduced to the market with favorable ion release, tooth remineralization, and alkalizing potential. This study aims to evaluate and compare the pH buffering capacity and calcium and phosphate ion release of three commercially available bioactive resin composites and one conventional resin composite under simulated cariogenic acidic conditions (lactic acid, pH 4.0). Methods: Disc-shaped specimens (6 mm diameter × 2 mm thickness) will be fabricated from three bioactive composites—ACTIVA BioACTIVE Restorative, RE-GEN Bioactive Composite, and Predicta Bioactive Bulk Fill—and one conventional resin composite serving as a negative control. Specimens (n = 4 per material per time point) will be individually immersed in 10 mL of 0.1 M lactic acid adjusted to pH 4.0 and stored at 37 °C. Measurements will be conducted at 1 hour, 24 hours, 72 hours, and 7 days. Ph changes (ΔpH) will be recorded using a calibrated pH meter. Phosphate ion release will be quantified using a malachite green colorimetric assay (ApexBio K2245), and calcium ion release will be measured using a calcium colorimetric assay based on o-cresolphthalein complex-one chemistry (ApexBio K2291). Ion concentrations will be calculated from standard calibration curves and expressed as µg per disc. Data will be analyzed using two-way analysis of variance with appropriate post-hoc testing (α = 0.05). Clinically, materials that release more ions and buffer acid may better prevent recurrent caries at restoration margins, especially in high-caries-risk patients.