Evidence suggests that hydrogen peroxide may act as a tumor promoter.[54] Although more pronounced cervical root resorption is observed with thermal bleaching methods, intracorneal bleaching may also lead to dental root resorption.[54] Furthermore, severe damage to the dentin inside the crown and fracture of the tooth crown can occur due to this whitening method. [54]
However, the International Agency for Research on Cancer (IARC) has concluded that there is insufficient evidence to prove that hydrogen peroxide is carcinogenic to humans.[55] Recently, the genotoxic potential of hydrogen peroxide was evaluated. Results indicated that oral health products that contain or release hydrogen peroxide up to 3.6% will not increase an individual’s risk of cancer,[56] and are therefore safe to use in moderation.
