Oral infections are part of the diseases that we sometimes take lightly, they affect about 20 to 50% of the world population and are the main causes of tooth loss according to the World Health Organization. As these infections are of bacterial origin, the researchers wondered if the polyphenols contained in tea are able to reduce the occurrence of these infections.
Caries and periodontitis: two sides of a coin
Teeth are made up of two parts: the outer part covered with enamel, the white part which ensures the solidity of the teeth. The inner part or roots which are implanted in the alveolar bone of the jaw.
Caries do not appear on the surface of the teeth because acidic foods have dissolved the enamel. Indeed, the food deposits composed of carbohydrates will be used by the bacteria present in the mouth. They will be able to develop: it is the dental plaque. The metabolism of bacteria creates an acidic environment that dissolves the crystals that make up the enamel. Eventually, the enamel becomes demineralized, holes are formed. Bacteria will enter the enamel and create a progressive inflammation of the inner part of the tooth. If it is not treated, there can be loss of teeth.
Periodontitis is the result of an inflammation of the gums when the dental plaque accumulates between the enamel and the gum. Bacteria will progressively gain ground until damaging the deeper tissues at the level of the roots. Eventually, this can lead to destruction of the jawbone and tooth loss. It is also important to remember that periodontal disease can be associated with the development of more serious diseases such as heart thrombosis or cardiac arrest due to chronic inflammation.
Tea polyphenols: natural antibacterial
In 2011, a research team had already demonstrated that the polyphenols contained in green and black tea had an antibacterial action on a wide spectrum of bacteria common in human infections. They reduced the proliferation of certain bacteria by up to 4 to 20 times.
Thus, this year, Mazur et al. compiled 15 follow-ups of patients who consumed green tea (randomized trials from 2000 to 2019). The authors then evaluated the antibacterial potential of green tea on the treatment of caries and periodontal disease compared to conventional treatments (chlorhexedine-based mouthwash, triclosan-based toothpaste). They also evaluated the evolution of the general state of the gums according to the treatments (less plaque, less bleeding, thicker gums).
Among the selected studies, the authors found that green tea decreased the proliferation of bacteria (Streptococcus mutans, Lactobacillus spp) which seems to be in correlation with previous studies which seemed to demonstrate the antibacterial potential of green tea. Moreover, green tea would improve the general condition of the gums compared to no treatment (less bleeding, thicker gums, less plaque).
However, the selected studies seem to be subject to many biases related to the diagnosis of general gum condition and to the consistency of the patients (poor treatment uptake, irregular tea consumption). Interestingly, these biases do not seem to have affected the assessment of bacterial proliferation, which could be due to the reliability of the commonly deployed tests. In addition, while green tea appears to show a better effect than the triclosan and placebo groups, this is not the case with the chlorhexidine group. It is therefore difficult at this time to affirm that green tea could be a treatment on its own. Finally, although the results are more encouraging for periodontal disease, the authors did not find a positive effect of green tea on the treatment of caries.
In relation to these different data, it would seem that green tea would decrease the proliferation of bacteria in the oral cavity, especially in people with oral infections. The effects of green tea seem to be positive on the health of the gums but are not more effective than some reference treatments. There would be no effect of green tea on caries.
Knowing that the vast majority of the follow-ups date from after 2010, these first results are very encouraging.