Objectives: The effects of tea components on the acid resistance of hu
man tooth enamel were investigated by an in vitro experiment. A furthe
r study focused on the action of tannin, the main component of tea, in
combination with fluoride. Results: Some components such as tannin, c
atechin, caffeine and tocopherol were demonstrated to be effective for
increasing acid resistance, and their effects increased dramatically
when they were used in combination with fluoride. A mixed solution of
tannic acid and fluoride showed the highest inhibitory effect (98%) on
calcium release to an acid solution. Tannin in combination with fluor
ide showed obvious inhibition of the formation of artificial enamel le
sions in comparison with APF as determined by electron probe microanal
ysis, polarized-light microscopy and Vickers microhardness measurement
. Conclusions: These results demonstrate that besides the fluoride, th
e organic components of tea also possess the property of increasing th
e acid resistance of tooth enamel. They also suggest that the organic
components appear to play a primary role in their actions rather than
fluoride.