Acute Oral Health Benefits of Chewing Plectranthus amboinicus: A Clinical Pilot Study on Salivary Pathogens, pH, and Plaque

Objective: To evaluate the acute effects of chewing fresh Plectranthus amboinicus leaves on oral health parameters, including salivary microbiology, physicochemical properties, and clinicalindices. Materials and Methods: A single-blind, randomized, controlled, crossover pilot study was conducted with 25 healthy adults. Participants underwent two interventions on separate days: chewing fresh P. amboinicus leaves (experimental) or a tasteless cellulose gum (control) for 5 minutes. Salivary levels of Streptococcus mutans and Candida albicans, pH, flow rate, total antioxidant capacity (TAC), Plaque Index (PI), Gingival Index (GI), and volatile sulfur compounds (VSCs) were measured at baseline, immediately post-intervention (T1), and at 120 minutes (T3). Acceptability was recorded via questionnaire. Results: Chewing P. amboinicus resulted in a significantly greater and sustained reduction in salivary S. mutans and C. albicans counts compared to control (p<0.001), with effects persisting at T3. It induced a significantly stronger increase in salivary pH (to 7.65 ± 0.28 at T1 vs. 7.10 ± 0.25 for control, p<0.001) and boosted TAC at T3 (p<0.001). Significant reductions in PI and VSCs (68% reduction at T1) were also observed uniquely with P. amboinicus (p<0.01). The intervention was rated as highly acceptable (92%). Conclusion: Chewing fresh Plectranthus amboinicus leaves provides immediate, multi-mechanistic oral health benefits—including antimicrobial, alkalinizing, antioxidant, anti-plaque, and anti-malodor effects—significantly surpassing mechanical chewing alone. This validates its traditional use and positions it as a promising natural adjunct for oral hygiene.