Tooth whitening has been the subject of extensive clinical trials research since the introduction of the first hydrogen-peroxide whitening strips in 2000. Availability of digital image analysis, an unambiguous and reproducible method for assessing color change, has contributed to global clinical research and product development on whitening strips. The research has included a series of global randomized controlled trials in distinct sites and cultures, involving 6-6.5% hydrogen peroxide whitening strips used for 7-21 days. These studies, conducted at research hospitals, dental schools, and private dental practice, demonstrated significant color improvement with whitening strips relative to baseline and/or various controls without serious adverse events. This integrated clinical trials research provides important evidence of long-term safety and effectiveness of tooth whitening with 6-6.5% hydrogen peroxide whitening strips.