Objective To observe the effect of green tea extractive epigallocatechin-3-gallate（EGCG） on degradation of collagen in dental erosion. Methods Sixty-four volunteers with dental erosion were randomly divided into two groups. The custom fitted trays were made from the heat curable braces and were injected with carboxymethyl cellulose sodium（CMC） hydrogel in one group（control group） or CMC hydrogel with EGCG added in another（experimental group）. These trays were used during sleep and removed from oral cavity in the next morning. The content of carboxy-terminal telopeptide of type Ⅰ collagen（ICTP） were determined by radioimmunoassay kit at 1 d before the experiment, and 1, 2, 3, 4 weeks after the experiment. Results Both the types and time showed significant effects on ICTP. The incubation in EGCG resulted in relatively rapid and significant（P
