Antimicrobial activity of garlic, tea tree oil, and chlorhexidine against oral microorganisms

Int Dent J. 2002 Dec;52(6):433-7. doi: 10.1111/j.1875-595x.2002.tb00638.x.


Objective: To compare the antimicrobial activity of tea tree oil, garlic, and chlorhexidine solutions against oral microorganisms.

Method: The five-week study consisted of thirty subjects. The first week was considered baseline. All subjects used a control solution (second week), and were randomly divided into the three groups (third week): G1-0.12% chlorhexidine; G2 - 2.5% garlic (Allium sativum, L.); and G3 - 0.2% tea tree oil (Melaleuca alternifolia). Dishes containing blood agar and Mitis Salivarius Bacitracin agar (MSB) were inoculated with the subjects' saliva (collected twice a week). Total microorganisms and mutans streptococci were counted in blood agar and MSB, respectively.

Results: Chlorhexidine and garlic groups showed antimicrobial activity against mutans streptococci, but not against other oral microorganisms. The tea tree oil group showed antimicrobial activity against mutans streptococci and other oral microorganisms. Maintenance of reduced levels of microorganisms was observed only for garlic and tea tree oil during the two consecutive weeks (fourth and fifth). Unpleasant taste (chlorhexidine 40%, tea tree oil 30%, garlic 100%), burning sensation (chlorhexidine 40%, tea tree oil 60%, garlic 100%), bad breath (chlorhexidine 40%, tea tree oil 20%, garlic 90%), and nausea (chlorhexidine 0%, tea tree oil 10%, garlic 30%) were reported.

Conclusion: Garlic and tea tree oil might be an alternative to chlorhexidine.

Publication types

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

MeSH terms

  • Adolescent
  • Adult
  • Anti-Infective Agents, Local / pharmacology*
  • Bacteria / drug effects*
  • Burning Mouth Syndrome / chemically induced
  • Chlorhexidine / pharmacology*
  • Colony Count, Microbial
  • Female
  • Garlic*
  • Halitosis / chemically induced
  • Humans
  • Male
  • Melaleuca*
  • Microbial Sensitivity Tests
  • Mouthwashes / adverse effects
  • Mouthwashes / pharmacology*
  • Plant Extracts / adverse effects
  • Plant Extracts / pharmacology
  • Plant Oils / adverse effects
  • Plant Oils / pharmacology
  • Saliva / microbiology
  • Streptococcus mutans / drug effects
  • Taste


  • Anti-Infective Agents, Local
  • Mouthwashes
  • Plant Extracts
  • Plant Oils
  • Chlorhexidine