Nanoemulsions containing volatile oils as novel antimicrobial for oral health care products

Dental caries is one of the most common diseases in children. Streptococcus mutans has been identified as a plaque forming bacterium and able to produce dental caries. This work demonstrated the guideline for development of oral health care products for eradication of S. mutans through nanoemulsification with volatile oils. Nanoemulsions were prepared by a simple emulsification method. Formulation factors, including type, amount of surfactants and oils were evaluated by monitoring of particle size, particle charge of oil droplets as well as other physical stability. The emulsions containing Cremophor®RH40, as a surfactant, showed relatively smaller oil droplets comparing to those containing Tween®60 or sodium lauryl sulfate. The result suggested that physical stability of nanoemulsions could be formed by specific selection of type and amount of surfactants. Nanoemulsions containing spearmint, peppermint, and tea tree oils, individually, demonstrated good physical stability as compared to that containing clove oil. The optimized formula was tested on antimicrobial properties against S. mutans. The nanoemulsions containing spearmint, peppermint and tea tree oils indicated 100% killing at the level of 10-fold dilution while that containing eucalyptus oil showed 95% killing. The knowledge gain from the study should provide the guideline for formulation of stable and effective oral health care products.