An in vitro evaluation of radicular penetration of hydrogen peroxide from bleaching agents during intra-coronal tooth bleaching with an insight of biologic response.

External root resorption is the complication of intra-coronal bleaching done with 30% H2O2 alone or mixed with sodium perborate but not with sodium perborate mixed with water. The study was done to comparatively evaluate the H2O2 leakage from three H2O2 liberating bleaching agents. Fifty one single rooted human teeth were used. After root canal therapy gutta percha was removed below cemento-enamel junction. Three bleaching agents: sodium perborate mixed with water, sodium perborate mixed with 30% H2O2 and 30% H2O2 alone were used. Teeth without defect, with cervical root defect and with mid root defect constituted group A, group B and group C. According to various bleaching agents groups were subdivided into subgroup 1, 2 and 3. H2O2 leakage was measured with the help of spectrophotometer Almost all teeth showed H2O2 leakage. It was maximum in B1 followed by C1, B2, A1, A2, C2, B3, A3 and C3. Sodium perborate mixed with water was found to be the best bleaching agent.