[Effect of tea on fluoride in plaque and saliva]

To evaluate whether tea drinking in a Chinese way in the Chinese population would affect fluoride in plaque and saliva.

Two groups of students were involved. Group 1, 41 subjects, did not drink tea regularly. Group 2, 34 subjects, drank tea every day in a very regular way. During a study period of three weeks, Group 2 was requested to drink selected (known fluoride concentration) types of tea, and subdivided by the type of tea they drank into two subgroups, Groups 2a and 2b. Group 2a drank lower fluoride tea, while Group 2b drank higher fluoride tea. Plaque and saliva samples were collected at the 2nd and the 3rd end of week, respectively. Fluoride levels were determined with fluoride selective electrode.

Both plaque and saliva fluoride were higher in the tea drinking group compared with non-tea drinking group. Plaque fluoride in tea drinking group at the end of three week was significantly higher than the value of non-tea drinking group (t test, P = 0.02). In tea drinking group, three week plaque fluoride was higher than two week plaque. Plaque fluoride level was also significantly corresponded to fluoride in tea. Drinking higher fluoride tea resulted in higher fluoride in plaque. But saliva fluoride was not shown the correlation with tea.

Tea is an important fluoride source. Plaque is a main resorvior of fluoride. Saliva has not the ability to store fluoride up. When considering tea as a fluoride source, the type of tea which may contain different concentration of fluoride should be borne in mind.