Drinking green tea can help prevent periodontal infections. Periodontal infection is caused by bacteria and infections of the gums and around the bones of the teeth. It leads to gum swelling and bleeding. Periodontal disease can also cause a number of generalised health problems of the body such as heart disease, stroke and diabetes. See your dentist if you suffer these symptoms.
Ramasamy C. Potential natural antioxidants: adjuvant effect of green tea polyphenols in periodontal infections. Infect Disord Drug Targets. 2015. https://www.ncbi.nlm.nih.gov/m/pubmed/26321324/?i=36&from=dental%20prevention%20antioxidants