In vitro efficacy of essential oil mouthrinse versus dentifrices

To compare the antimicrobial efficacy and kill penetration of essential oils (EO) mouthrinse versus stannous fluoride, and triclosan dentifrice slurries on saliva-derived biofilms using confocal laser scanning microscopy (CLSM).

Saliva-derived biofilms were grown for 48h on hydroxyapatite discs using pooled, homogenized saliva from 8 healthy volunteers as the inoculum. The mean thickness of these biofilms was 84μm (range, 23-241μm). CLSM with viability mapping was used to visualize the antimicrobial kill penetration of each treatment regime within a biofilm.

At 30s treatment durations, CLSM imaging revealed greater antimicrobial activity and kill penetration of EO mouthrinse compared to sodium fluoride-, stannous fluoride-, and triclosan-containing dentifrice slurries. Quantification of biovolume revealed that EO mouthrinse treatment at 30s resulted in a greater non-viable biovolume proportion (84.6%±15.0%) than other treatment groups. Increasing the treatment duration of the triclosan dentifrice (to 60 and 120s) resulted in better penetration and an increased reduction of viable cells, comparable to EO mouthrinse treatment at 30s duration. Further, CLSM imaging showed that the combined treatment of a non-antimicrobial dentifrice (45s) with EO mouthrinse (30s) showed superior antimicrobial activity (96.2%±3.7%) compared to the antimicrobial triclosan-containing dentifrice used without a mouthrinse step (26.0%±32.0%).

Within typical exposure times, the EO-containing mouthrinse can penetrate deep into the accumulating plaque biofilm compared to the chemotherapeutic dentifrice slurries, and may provide an efficacious alternative to triclosan, when used as an adjunct with a mechanical oral care regimen.

Using viability mapping and CLSM, this study demonstrated that EO-containing mouthrinse penetrates and kills microorganisms deeper and more effectively in plaque biofilm in typical exposure times when compared to dentifrice chemotherapeutic agents, providing an efficacious alternative to triclosan or stannous fluoride when used as an adjunct to mechanical oral care.