I KNOW I got greater-than-expected results from Crest 2-Hour Express, because I only applied part of a strip to half my upper teeth. So, I have a 3-tooth permanent bridge and my lower teeth for comparing the results. We all know that peroxide works – it is what women used to bleach their hair. We all know that it is cheap, so Crest did not skimp, but used as much as was safe, and wouldn’t damage the teeth. First, I dried my teeth and mouth.
I was cautious, and only did a small strip on the top, first. Later, when I did the bottom, I cut the strip in half, so the application would be easier.