Whitening effectiveness of 10% and 15% carbamide peroxide on extrinsic discoloration by coffee

This study aimed at determining the whitening effectiveness of 10% and 15% carbamide peroxide on extrinsic discoloration by coffee. Thirty-two human premolar teeth were immersed in coffee solution for 8 days to achieve extrinsic discoloration as a base color. A home-bleaching whitening process was performed for 14 days. Color was measured three times: after extrinsic discoloration by coffee, after the application of home bleaching on day 7, and after the application of home bleaching on day 14. The CIE and VITAPAN systems and a VITA Classical Easyshade® spectrophotometer were used to make the color measurements. After extrinsic discoloration by coffee, the results indicated low L∗ (value), high positive a∗ (reddish-greenish chroma), and high positive b∗ (yellowish-bluish chroma). The results after the application using carbamide peroxide home bleaching showed increased L∗, decreased a∗, and decreased b∗ relative to before application. Visually, the teeth looked whiter than the normal human tooth color. Both concentrations of carbamide peroxide were effective in whitening teeth showing extrinsic discoloration by coffee. There was no statistically significant difference in the effectiveness of 10% and 15% carbamide peroxide against extrinsic discoloration by coffee when the effectiveness was measured by using the CIE system. However, there was a difference in effectiveness between the two concentrations on day 7 when the effectiveness was measured by using the VITAPAN Classical system.