Optimization of Tea Tree Oil and Eucalyptus Essential Oil Combinations in an Oral Rinse for Managing Oral Ulcers

Suyan Innovation Laboratory, Room 411, 4th Floor, Building D Chuangyue Incubator, No. 10 Financial Avenue, Ningxi Street, Zengcheng District, Guangzhou, China

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Abstract

This investigation sought to determine the optimal mixing ratio of tea tree oil (TTO) together with eucalyptus essential oil (EEO) within a mouthwash formulation. Four experimental preparations underwent evaluation regarding their safety profile, antimicrobial effectiveness, antiinflammatory properties, and sensory characteristics. Safety testing employed the chick embryo chorioallantoic membrane (CAM) model. Antibacterial activity was assessed against several clinically relevant oral pathogens. Anti-inflammatory potential was quantified through qPCR analysis conducted on human gingival fibroblasts. A future clinical trial framework was also designed. The CAM assay revealed that lower oil concentrations produced minimal irritation, whereas higher concentrations intensified irritant responses. All tested preparations demonstrated potent antibacterial effects, achieving over 99.9% inhibition against E. coli, S. aureus, and S. mutans, together with approximately 93% inhibition against P. gingivalis. qPCR data indicated marked downregulation of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, and IL-8. A concentration-dependent relationship was observed between essential oil levels and anti-inflammatory potency, although taste acceptability declined at elevated concentrations. In summary, essential oil-based oral rinses exhibit considerable antibacterial together with anti-inflammatory potential suitable for oral ulcer management. The formulation combining 0.2% TTO plus 0.2% EEO delivered the most favorable balance across efficacy, safety, and user acceptability parameters.