Ever used Crest Whitestrips?

Crest Whitestrips is the name of a tooth whitening product made by Procter & Gamble. Introduced in 2001, Crest Whitestrips has been used worldwide by selling to over 14 million homes. The active ingredient is hydrogen peroxide. The product is used by sticking a strip to the teeth and usually has some minor to moderate effect[citation needed]. It is most effective on yellow teeth, but less so or almost ineffective on gray teeth[citation needed]. Like most teeth whiteners, a side effect of Whitestrips is a slight stingy sensation in the gum that may be occasionally piercing