UV light-enhanced tooth bleaching has no advantage over bleaching without UV, and also poses a dangerous threat to eyes and skin, according to a study in Photochemical & Photobiological Sciences.
The study reveals that the light treatment gives absolutely no benefit over bleaching without UV, and damages skin and eyes up to four times as much as sunbathing. Additionally, as with sunbathing, fair-skinned or light-sensitive people are at even greater risk of damage, according to lead author Ellen Bruzell of the [removed]Nordic Institute of Dental Materials[/removed].
Bruzell also found that this method of bleaching damages teeth. She saw more exposed grooves on the enamel surface of bleached teeth than on unbleached teeth. These grooves make the teeth more vulnerable to mechanical stress.
The authors of this article say there is very little substantive evidence to support the claim that UV light further activates the oxidation process to improve bleaching efficiency.

[Source: ScienceDaily]