i just got this pack of tooth whitening powder..
The brand is Eucryl (UK) and it says to use it only 1-2 times a week.
So how long would it usually take to get rid of stains (mainly smoking) and whiten teeth?

I’ve never used any teeth whitening products and I’d like to remove some stains from my teeth. So which one/ones works the best? A d does the white eventually fade back to the same color your tooth was before to where you’d have to whiten them again? If so, how long does the white usually [...]