I’ve tried a handful of different whitening strips, most of which cover about eight of my front teeth (on the top and bottom). In theory, that’s fine, because who’s really looking at my molars? But in reality, that’s weird. They work, visibly whitening my teeth after just one use, so if I use them repeatedly I’m heading toward 16 teeth of one color and more of another. Crest has finally addressed this problem, with their new 3D White Whitestrips Luxe Supreme FlexFit ($55). They say they stretch to cover 30 percent more teeth, but they actually covered all of mine. They’re also wondrously thin so that while they’re on I can speak without a lisp and comfortably drink water. Who knew a good thing could get so much better?