Insights into blue light accelerated tooth whitening.

Objective: To test the hypotheses that blue light accelerates whitening through either (1) direct photobleaching or (2) photon-assisted oxidation using sequential longitudinal bleaching.

Methods: Thirty extracted human tooth samples having natural life accumulated color were divided over five groups: A. 9h light + 10h 6% HO gel + 6h light & 6% HO combined; B.