Background: To assess the reversal of discolouration caused by Ledermix using various bleaching agents.

Material and methods: Twenty six extracted human mandibular premolars were taken and divided into four groups. Six teeth were divided into three each which are taken as positive and negative controls. The remaining twenty are divided into two groups (n=10). After conventional access preparation, the Ledermix paste was sealed in the pulp chamber for twelve weeks. The paste was removed by a rinse with sodium hypochlorite (NaOCl). Then the pulp chamber was sealed with a mixture of Sodium perborate and distilled water for group 1 and group 2 was sealed with Sodium tetraborate for 1 to 12 weeks. The shade was measured by a Spectrophotometer at four time periods baseline(T0), after 12 weeks of placement of Ledermix (T1), after 4 (T2), 12 (T3) weeks of Internal bleaching with Sodium perborate and Sodium tetraborate respectively. Data were collected based on CIE-76 (L*a*b*) system and analysed using t-test and ANOVA.

Results: A significant decrease in the mean value of L*(lightness) was observed after treatment with Ledermix (T1, p<0.05). Considerable increase in these values after bleaching with Sodium perborate and Sodium tetraborate (T2, T3) were found in both groups, to the same extent.

Conclusions: Ledermix discoloured the tooth structure but discolouration could be reversed when bleached with both Sodium perborate and Sodium tetraborate to the same extent. Key words:Bleaching, discoloration, ledermix, sodium perborate, sodium tetraborate.