In situ antimicrobial activity on oral biofilm: essential oils vs. 0.2 % chlorhexidine

This study aims to evaluate the in situ antibacterial activity of a mouthwash containing essential oils (M-EO) on undisturbed de novo plaque-like biofilm (PL-biofilm) up to 7 h after its application.

An appliance was designed to hold six glass disks on the buccal sides of the lower teeth, allowing PL-biofilm growth. Fifteen healthy volunteers wore the appliance for 48 h and then performed a M-EO. Disks were removed after 30 s and at 1, 3, 5, and 7 h later. After a washout period, the same procedure was repeated with a M-WATER and a M-0.2 % chlorhexidine. After PL-biofilm vital staining, samples were analyzed using a confocal laser scanning microscope.

At 30 s after M-EO, the levels of bacterial vitality were 1.18 %, significantly lower than that of the basal sample (p < 0.001). After 7 h, the antibacterial effect of essential oils was still patent with a 47.86 % difference in bacterial vitality compared to the basal sample (p < 0.001).

A single M-EO presents high antibacterial immediate activity and penetration capacity in situ and a substantivity which lasts for at least 7 h after its application over de novo biofilm. These results were better than those observed with 0.2 % chlorhexidine under the same conditions.

A single M-EO is an effective measure against the de novo biofilm, presenting a good alternative to clorhexidine such as a preoperative rinse, in periodontal procedures or post-treatment applications.