NCT03217994.

Methods	Title: efficacy of 2 teeth whitening gels. A prospective, double‐blind, randomised clinical trial with split‐mouth design
Participants	Adults without prior tooth whitening treatments, tooth decay, or restorations of the upper front teeth. The patients had tooth colours of A3 or less according to the Vita classical scale
Interventions	37.5% hydrogen peroxide gel to bleach teeth 6% hydrogen peroxide gel to bleach teeth
Outcomes	Change in tooth colour
Notes	A protocol for a randomised controlled trial. Full text not available