Abstract: PURPOSE: To evaluate the clinical effectiveness of cold-light whitening technique on tetracycline pigmentation teeth and aged extrinsic stain teeth. METHODS: One hundred and fifty-two cases bleached by cold-light whitening technique were included in this study. The patients' teeth were divided into 3 groups: aged extrinsic stain teeth, mild tetracycline pigmentation teeth and moderate tetracycline pigmentation teeth. Visual determination of shade and Olympus crystaleye spectrophotometer were used to measure the tooth discoloration after bleaching. SPSS17.0 software package was used for statistical analysis. RESULTS: Visual determination showed that the efficiency of aged extrinsic stain teeth was significantly higher than that of mild and moderate tetracycline teeth group (P<0.05). Colorimetric method showed that the △E of moderate tetracycline teeth was significantly lower than aged extrinsic teeth and mild tetracycline teeth (P<0. 05) . The △E of cervix changed more significantly than that of central and incisal edge in both mild and moderate tetracycline teeth group (P<0. 05). CONCLUSIONS: The effect of cold-light whitening technique on aged extrinsic stain teeth is better than that of the tetracycline pigmentation teeth. Cold-light whitening technique can improve pigmentation of tetracycline teeth cervix．

Key words: Cold-light whitening technique, Tetracycline pigmentation teeth, Colorimetry, Chroma