There’s a new, small study  out suggesting that “essential oil mouth rinse” may not improve your periodontal health all that much if you’re already pretty diligent with your hygiene.
So are essential oils just a kind of gimmick?
It depends on what kind of oils you’re talking about.
The study, published in the International Journal of Dental Hygiene, looked at just one product: Listerine CoolMint, which contains thymol (derrived from thyme), eucalyptol (eucalyptus), methyl salicylate (derrived from a variety of plants) and menthol (mint). While the last two are soothing, only the first two have antimicrobial qualities – especially the thymol (eucalyptol depends on the particular species it’s derrived from). Yet perio health depends on managing microbial balance in the mouth, so its not really so surprising that this particular blend of oils would have limited effect.
Other oils, however, have proven effective in keeping the “bad bugs” in check.
For instance, clove oil has long been used as a dental remedy, but others, such as cinnamon oil, appear to be even better. A study  published late last year in Acta BioMedica found it “more effective than clove oil exhibiting broad spectrum of antibacterial activity inhibiting all the ten test bacterial species involved in dental caries.”
This was supported by a study  published about a month later in the Journal of Contemporary Dental Practice. This time, researchers evaluated 9 different oils and found 5 of them effective against S. mutans, one of the key players in oral disease. While wintergreen, lime, spearmint and peppermint showed no antibacterial activity, cinnamon, lemongrass, cedarwood, clove and eucalyptus did. Cinnamon was most powerful, followed by lemongrass and cedarwood. The authors concluded that
the use of these essential oils against S. mutans can be a viable alternative to other antibacterial agents as these are an effective module used in the control of both bacteria and yeasts responsible for oral infections.
It’s the kind of essential oil that matters.