Role of cementoenamel junction on the radicular penetration of 30% hydrogen peroxide during intracoronal bleaching in vitro.

Intracoronal bleaching of nonvital, teeth with 30% hydrogen peroxide is occasionally associated with external cervical root resorption. The exact mechanism by which bleaching induced root resorption occurs is not yet fully understood. The relationship of cementum to the enamel at the cementoenamel junction may have clinical significance. Seventeen single rooted human mandibular premolars extracted atraumatically for orthodontic reasons were used. The radicular hydrogen peroxide penetration in each tooth was measured in vitro by an indirect colorimetric method. Thereafter, the teeth were examined with a scanning electron microscope to determine the type of the cementoenamel junction. It was found that the radicular penetration of 30% hydrogen peroxide was related to the type of cementoenamel junction.