Oral green and red propolis attenuate bone resorption and inflammation in experimental apical periodontitis

OBJECTIVE: To test whether systemic green or red propolis modulates inflammation and bone resorption in rat apical periodontitis (AP). DESIGN: Twenty-four male Wistar rats received AP induction in the first mandibular molars and were randomized to Control, Green propolis, or Red propolis (n = 8/group). Propolis (100 mg/kg in water) or vehicle was administered daily by gavage for 30 days. On day 30, periapical tissues were evaluated by micro-CT, histology (inflammatory score), and immunohistochemistry for RANKL, OPG, and TRAP-positive osteoclasts. Data were analyzed with Shapiro-Wilk, Kruskal-Wallis/Dunn, or one-way ANOVA/Tukey (α=0.05). RESULTS: Both propolis groups showed significantly less periapical bone resorption than the control group on micro-CT analysis (p < 0.05). Histological evaluation revealed predominantly chronic inflammatory infiltrates, with significantly lower inflammation scores in the propolis-treated groups (p < 0.05). Immunohistochemical analysis demonstrated a significant reduction in RANKL expression, an increase in OPG levels, and fewer TRAP-positive multinucleated cells in both propolis groups compared to the control (p < 0.05). No significant differences were observed between green and red propolis. CONCLUSION: Thirty days of systemic green or red propolis similarly attenuated periapical inflammation and osteoclast-mediated bone resorption in experimental AP, reflected by lower resorption volumes, reduced RANKL/TRAP, and higher OPG, indicating that propolis may serve as a host-modulatory adjunct to preserve periapical bone.