Study Finds Tea Tree Oil Exhibits Strong Anti-Plaque Effect in High-Risk Caries Patients

A recent study published in Scientific Reports and reported by Oral Health Group indicates that tea tree oil (TTO) may be a powerful natural agent for reducing dental plaque and preventing cavities, particularly in individuals at high risk for caries. The researchers, based at the University of Saskatchewan, tested TTO against two primary cariogenic bacteria — Streptococcus mutans and Streptococcus sobrinus — and observed robust inhibitory effects on bacterial growth, biofilm formation, and adhesion to tooth surfaces. 

In laboratory (in vitro) experiments, a 12.5% concentration of TTO completely suppressed bacterial proliferation, prevented biofilms from forming, and blocked the bacteria from sticking to enamel surfaces. Then, in an animal (in vivo) rat model, the team applied TTO treatments and monitored dental lesions: rats receiving TTO treatment developed fewer and shallower carious lesions compared to untreated controls (average of 13 lesions vs. 19). The reduction in lesion area was statistically significant (p = 0.003). Importantly, TTO did not appear to interfere with reparative dentin formation, implying that its primary effect is antimicrobial rather than affecting the tooth’s natural repair processes.

The study authors highlight that while traditional antimicrobial agents — such as chlorhexidine — are effective, they can cause side effects like tooth staining, toxicity, and dry mouth (xerostomia). TTO could offer an alternative or adjunct approach with fewer adverse effects, especially for patients who struggle with mechanical plaque removal, have low saliva flow, or face high bacterial adhesion.

That said, the researchers caution that further clinical trials are needed. The current findings, though promising, derive from controlled laboratory and animal settings, and may not fully reflect the complexity of the human oral environment. Future studies should include a broader array of oral bacterial species, larger sample sizes, and direct clinical testing in humans to validate safety, efficacy, and optimal concentrations.The investigation into natural compounds like TTO underscores growing interest in integrating biologically based strategies into caries prevention, particularly for populations at high risk.

📖 Original Article Information

“Could tea tree oil help high-risk caries patients? Study finds strong anti-plaque effect.”

Oral Health Group, September 2, 2025