Prior to switching to cleaner/healthier products, I used to us Crest White Strips yearly to keep my teeth SUPER white. I ditched those when I got pregnant and I was hoping to find a non-toxic product to replace them and settled on Lumineux. I'm on day 9 of using the pens as a whitening treatment and I do think my teeth look a bit less dingy, but definitely didn't get results that I'm used to from Crest.
My one suggestion is : instructions don't mention drying off teeth prior to applying and I DEFINITELY recommend doing so. If your teeth aren't dry, the product struggles to stick. So I think taking that extra measure is important to see effective results. All this being said, I will probably purchase again but might pair the pens with another Lumineux product to try and get my teeth another shade or two whiter.