Antiplaque effect of essential oils and 0.2% chlorhexidine on an in situ model of oral biofilm growth: a randomised clinical trial

PLoS One. 2015 Feb 17;10(2):e0117177. doi: 10.1371/journal.pone.0117177. eCollection 2015.


Objective: To evaluate the in situ antiplaque effect after 4 days of using of 2 commercial antimicrobial agents in short term on undisturbed plaque-like biofilm.

Trial design and participants: An observer-masked, crossover randomised clinical trial on 15 oral and systemically healthy volunteers between 20-30 years who were randomly and sequentially allocated in the same group which performed 3 interventions in different randomised sequences.

Intervention: The participants wore an appliance in 3 different rinsing periods doing mouthwashes twice a day (1/0/1) with essential oils, 0.2% chlorhexidine or sterile water (negative control). At the end of each 4-day mouthwash period, samples were removed from the appliance. Posteriorly, after bacterial vital staining, samples were analysed using a Confocal Laser Scanning Microscope.

Main outcome measures: Bacterial vitality, thickness and covering grade by the biofilm after 4 days of applying each of the mouthwashes.

Results: The essential oils and the 0.2% chlorhexidine were significantly more effective than the sterile water at reducing bacterial vitality, thickness and covering grade by the biofilm. No significant differences were found between the 0.2% chlorhexidine and the essential oils at reducing the bacterial vitality (13.2% vs. 14.7%). However, the 0.2% chlorhexidine showed more reduction than the essential oils in thickness (6.5 μm vs. 10.0 μm; p<0.05) and covering grade by the biofilm (20.0% vs. 54.3%; p<0.001).

Conclusion: The essential oils and 0.2% chlorhexidine showed a high antiplaque effect. Although the 0.2% chlorhexidine showed better results with regard to reducing the thickness and covering grade by the biofilm, both antiseptics showed a high and similar antibacterial activity.

Clinical relevance: Daily essential oils or 0.2% chlorhexidine mouthwashes are effective when reducing dental plaque formation in the short term. Although 0.2% chlorhexidine continues to be the "gold standard" in terms of antiplaque effect, essential oils could be considered a reliable alternative.

Trial registration: NCT02124655.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Anti-Infective Agents, Local / pharmacology*
  • Biofilms / drug effects*
  • Biofilms / growth & development*
  • Chlorhexidine / pharmacology*
  • Cross-Over Studies
  • Dental Plaque / microbiology*
  • Female
  • Humans
  • Male
  • Microbial Viability / drug effects
  • Mouthwashes / pharmacology*
  • Oils, Volatile / pharmacology*
  • Time Factors


  • Anti-Infective Agents, Local
  • Mouthwashes
  • Oils, Volatile
  • Chlorhexidine

Associated data


Grant support

This work was supported by project PI11/01383 from Carlos III Institute of Health (General Division of Evaluation and Research Promotion, Madrid, Spain), which is integrated in National Plan of Research, Development and Innovation (PN I+D+I 2008-2011). This project was cofinanced by European Regional Development Fund (ERDF 2007-2013). The funders had no role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.