Tooth decay is caused by bacteria that secrete acidic substances that damage the teeth. Fluoridation of enamel (outer covering) and dentine (inner core) in teeth hardens them and makes these tissues more acid resistant.
The prevalence of dental caries (decay) is inversely related to fluoride intake. Tea contains significant amounts of fluoride in an easily assailable form. Tea drinking makes a significant contribution to the daily fluoride intake and to the reduction of tooth decay.
It has been found that not only fluoride but also the polyphenols in tea could act to reduce tooth decay. Tea polyphenols could inhibit the growth of bacteria, such as Streptococcus mutants, which cause tooth decay.
Recent research indicates that tea could inhibit the growth of other harmful micro-organisms in the oral cavity. It has been found that brewed black tea can inhibit the oral fungal species of Candida by 30%.
Increased populations of Candida in the oral cavity could cause candidiasis (oral thrush). Bacterial species cause infections in the root canal, and research has found that tea could inhibit the growth of some bacterial species that cause infections in the oral cavity.
These findings demonstrate that tea drinking may improve oral health.