In vitro comparison of different types of sodium perborate used for intracoronal bleaching of discoloured teeth

Aim To compare the bleaching efficacy of three different types of sodium perborate (SP) commonly used for intracoronal bleaching of discoloured non-vital teeth. Methodology Sixty-five extracted human maxillary central incisors with intact crowns were used. Following obturation with gutta-percha and a root canal sealer using a lateral condensation technique, the coronal aspects of the root canal fillings were covered with a 1-mm thick protective base placed to a level 1 mm apical to the labial cemento-enamel junction (CEJ). The teeth were than stained artificially with fresh blood over a period of 18 days. One or other of the bleaching materials (group 1: SP monohydrate + water, group 2: SP trihydrate + water, group 3: SP tetrahydrate + water, group 4: SP monohydrate + hydrogen peroxide (HP), group 5: SP trihydrate + HP, group 6: SP tetrahydrate + HP) were placed in the pulp chamber of the discoloured teeth and sealed with Cavit for 21 days. They were replaced with fresh preparations after 3, 7 and 14 days. The shades of the tooth crowns were evaluated at baseline and at 7, 14 and 21 days. Comparison of tooth shades was completed at each interval and analysed statistically using the chi-squared test. Results There was no statistically significant difference between the groups at 7, 14, 21 days. Period of bleaching significantly affected the outcome (P < 0.01). No colour changes were noted in the control teeth. Conclusion The data obtained from this study demonstrate that sodium perborate can be used mixed with water rather than with hydrogen peroxide for bleaching discoloured teeth.