The purpose of this study was to compare the bleaching effects of peroxide-free and peroxide-containing tooth whitening products. We chose four tooth whiteners from internet and pharmacies, and one distributed through the dental office. These products were tested using five extracted teeth for each product (totally 25 teeth). Products were tested on buccal and lingual surfaces selected randomly. The whitening processes were performed according to the manual of the different products. Two authors (ELM and OBL) examined the teeth in a light box, and the tooth color was given according to the Vita Lumin-Vacuum colour scale. The evaluations were done prior to the treatment, immediately after the whitening, and after eight months. Both peroxide-free and peroxide containing products gave an initial lightening of the tooth color. The mechanisms of actions were different for the two product types. The lightening of the peroxide-free was due to acid erosion of the enamel surface changing the reflection of light. For the peroxide containing product the bleaching effect was caused by oxidation of chromophores in enamel and dentin. After 8 months, no perceivable lightening was noted for the peroxide-free products whereas the teeth treated with peroxide containing bleaching remained lightened.

Peroxide-free tooth whitening products
Møller EL, Lien OB, Dahl JE.
Nor Tannlegeforen Tid. 2018; 128: 772–7