Illuminating the evidence: A comprehensive review of light-assisted in-office tooth bleaching

ABSTRACT Objective To critically synthesize evidence on the role of light sources in in-office tooth bleaching, including high-power lasers, LEDs of different wavelength profiles, photocatalytic bleaching strategies, and photobiomodulation (PBM), focusing on their mechanisms, efficacy, and safety. Study selection A narrative review was conducted using a structured and comprehensive search strategy across PubMed, Scopus, Web of Science, and selected grey literature. After duplicate removal, title/abstract screening, and full-text evaluation, 242 studies were included (predominantly in vitro and randomized clinical trials - RCT). Only in-office bleaching protocols using lasers and LEDs were included, while studies based on at-home systems, halogen, xenon lamps, and plasma devices were excluded. Conclusions Evidence indicates that investigated visible-light sources did not consistently enhance bleaching efficacy of high-concentration hydrogen peroxide (HP). Wavelength-screening experiments show that meaningful photochemical enhancement occurs within the near-UV range, which is clinically undesirable. Conversely, violet LEDs (combined with low-concentration HP (6–15%) demonstrated improved efficacy and reduced sensitivity. When paired with photocatalysts, such as TiO 2 , violet LED can further potentiate gel’s efficacy while maintaining biocompatibility. Further RCT are necessary to confirm these findings. PBM (660–810 nm) does not activate peroxide but may modulate pulpal inflammation, although clinical analgesic effects remain inconsistent and protocol-dependent. Clinical Significance Current evidence does not confirm the clinical necessity of light activation for high-concentration gels. The most promising emerging approach is the violet LED-assisted activation of low-concentration peroxide or photocatalytic systems and PMB for modulating tooth sensitivity.