Evaluation of the Remineralisation and Antibacterial Properties of Propolis, Chitosan, and Theobromine.

PURPOSE: This study evaluated the remineralisation potential of the natural compounds propolis, chitosan, and theobromine on artificial initial carious lesions and investigated their antibacterial and anti-biofilm activities. METHODS AND MATERIALS: Artificial lesions were induced on buccal and lingual enamel surfaces of 14 extracted molars through a 72-h demineralisation process. Specimens were randomly assigned to seven groups (n = 4): propolis (100, 200 μg/mL), chitosan (1.25, 2.5 mg/ml), theobromine (100, 200 mg/L), and artificial saliva (control). Mineral density was assessed using micro-computed tomography (micro-CT) at baseline, after demineralisation, and after pH cycling. The minimum inhibitory concentration (MIC) was determined by broth microdilution, and antibiofilm effects were evaluated using confocal laser scanning microscopy (CLSM). RESULTS: Micro-CT showed that both propolis groups exhibited mineral gain and % remineralisation values similar to the negative control, whereas chitosan and theobromine groups had significantly higher values (P 0.05). MIC values were 100 μg/ml for propolis and 0.15 mg/ml for chitosan, while theobromine showed no effect. Quantitative CLSM analysis revealed that only the propolis 200 µg/ml group had a significantly lower total biomass compared to the negative control (P 0.05). Additionally, both propolis groups demonstrated a significantly higher dead/live cell ratio than the negative control groups (P 0.05). However, no significant differences in dead/live cell ratios were observed among the chitosan, theobromine, and negative control groups (P > 0.05). CONCLUSION: Chitosan and theobromine exhibited favourable outcomes in terms of remineralisation; however, their antimicrobial efficacy remained limited. In contrast, propolis exhibited promising antibacterial activity but lacked significant remineralisation capability.