Comparative evaluation of propolis, fluoride and probiotic mouthwashes on streptococcus mutans and oxidative stress in fixed orthodontic patients: A triple-blind, randomized controlled trial with 9-month follow-up

BACKGROUND: Fixed orthodontic appliances increase the risk of enamel demineralization due to plaque accumulation. While fluoride mouthwash is well established, propolis and probiotic formulations are emerging alternatives with antimicrobial and anti-inflammatory potential. AIM: To compare the effects of propolis, fluoride, and probiotic mouthwashes on Streptococcus mutans levels and oxidative stress (8-OHdG) in patients undergoing fixed orthodontic treatment. MATERIALS AND METHODS: Of 120 patients screened (March 2022-February 2023), 90 were randomized into three groups (n=30 each): propolis, fluoride, and probiotic. S. mutans was quantified at baseline, 30 days, 3-, 6- and 9-months using Q-PCR. Salivary 8-OHdG was measured using ELISA. Dietary and oral hygiene behaviours were monitored through a mobile app, interviews and 24-hour dietary recalls. RESULTS: S. mutans levels (log10 CFU/mL) significantly decreased (P<0.001) at 9 months: from 4.35±0.45 to 0.89±0.06 (propolis), 4.42±0.49 to 2.74±0.18 (fluoride), and 4.38±0.50 to 3.21±0.06 (probiotic). Ct values increased accordingly, confirming reduced bacterial load. Salivary 8-OHdG (ng/mL) declined significantly (P<0.001): 3.8±0.8 to 0.32±0.14 (propolis), 3.9±0.7 to 1.32±0.18 (fluoride), 3.8±0.6 to 2.42±0.22 (probiotic). CONCLUSION: Propolis mouthwash produced the greatest reductions likely due to the combined effect of standardized extract and essential oils added for taste. Fluoride remained effective for microbial control, while probiotics offered modest benefit. High compliance strengthened these findings. Further studies should isolate active components and assess long-term effects in broader settings.