The strips do not go all the way from side to side it covers only about 2.5-3 inches of your front teeth so even if it worked you would have nice white teeth on the front and still yellowish on the back

These white strips are so easy to use and no funky taste

I think these are the best strips I have tried, they are thick enough to stay in place and don't slide around too much..

So, I used Crest white strips about 6 years or so ago and these have improved a lot!It's important to note that these make you drool like crazy...but that's a reason to take off stars

The strips are easy to use