I've used them twice before and they definitely worked well for me. I noticed a difference after 3 days of using them. Some days I used one in the morning and one at night, some days I only did it once -- I played it by ear depending on how sensitive my gums were feeling that day.
They were slightly less effective for my bf, whose bottom front teeth are a little crooked - it was hard for the strip to cover all the surface of those teeth.
Also I found that the strips adhered best to dry teeth (then they didn't slide around on my teeth as much) so I was always wiping them with a dry washcloth right before application. Yeah, that must have looked silly.
I used them. I don't have super sensitive teeth, but I noticed a little sensitivity when using White Strips.
But they worked pretty well. I always compare my teeth to the whites of my eyes b/c I've heard that if they are the same shade it looks the most natural (not too yellow, and not glow-in-the dark, scary white) and these got my teeth a little whiter than that. I don't have really stained teeth or anything, so I'm sure the experience differs from person to person.
They work awesome.. In my opinion the best on the market! Sometimes I would use them twice and sometimes only once. If my teeth got sensitive, then I'd cut back to once that day.. and try two again the next.
They were awesome...I used them for my wedding 14 months ago and I can still see the effects. I couldn't use them more than 1x per day, though, because like Maddie, I was getting pain in my teeth even when they were'nt on (I do have sensitive teeth normally though).
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"We live in an age where unnecessary things are our only necessities." --Oscar Wilde
I used them a couple years ago when they only had the regular. I only used the top ones because I thuoght it was nasty enough to have them on the top teeth for 30 min. They didn't make my teeth sensitive though. They worked very well. I haven't used them again since my teeth really don't need whitening since my Mentatdent whitening toothpaste takes care of that.