Safety and Efficacy of a Light-activated 6% Hydrogen Peroxide With Nitrogen-doped Titanium Dioxide Tooth Bleaching Agent

This was a randomized, triple-blinded (patients, evaluator, and statistician), and split-mouth design (one hemiarcade was treated by 1 compound) following nonprobability sampling. The patients were invited to participate in the study through posters posted around the city or recruited from participants in other studies in the same department, who were contacted by email or phone.

A total of 131 patients were examined in a dental chair to check if they met the inclusion and exclusion criteria. The patients included in this study were over 18 years old and selected with the following inclusion criteria: anterior teeth without restorations, previous bleaching procedures, cervical lesions, or dental pain. Patients who were pregnant or lactating, had moderate or severe fluorosis, tetracycline stains, orthodontic treatment, periodontal disease, orofacial tumors, trauma, or tooth malformation, or were taking analgesic, anti-inflammatory, or antibiotic drugs were excluded.

Two trained operators (restorative dentistry professors) performed the bleaching treatments. A third participant that did not have contact with the patients was responsible for conducting the randomization. The allocation of the hemiarcade in the groups was performed by random drawing using Microsoft Excel 2010 (Microsoft, Redmond, Washington, USA) from coding assigned to each participant. There were two experimental groups: Group A acted as a control, and hydrogen peroxide whitening compound was applied at a concentration of 35% to the upper hemiarcade. Group B was the experimental group, in which the other upper hemiarcade was treated with 6% compound catalyzed by titanium oxide nanoparticles and activated by blue hybrid light and an infrared laser.

The distribution of the operators was made by block randomization. To ensure triple blinding, the following procedures were adopted: 1) labels, logos, packaging, and any other aspect that could identify the products were removed, and procedures and instruments were standardized; 2) the bleaching protocol was performed in a different room from where the evaluator examined the patients; 3) the randomization was alpha-numerically coded to ensure blinding of the research team; and 5) a statistician received data tabulated in code that did not allow for identification of the treatment applied to each group.

Sample size calculation The primary outcome of this study was the efficacy determined by color alteration (ΔE). Previous studies showed that the use of in-office bleaching agent containing 35% hydrogen peroxide (HP35) with or without LED/Laser light leads to a ΔE value of 7.0-2.0 after two bleaching sessions. In order to have an 80% chance of detecting significance at the level of 5%, and considering an increase in the primary outcome measure from 7 in the control group to 5 in the experimental group, a minimum of 16 participants would be required in each group. Due to a higher dropout rate in the last two clinical studies of our research group, we decided to add 80% more patients, which led to 30 patients in each group.