I noticed a bit of discoloration in my teeth like they are more yellowish. The stains and marks on my teeth are really gross. I barely smile because of my embarrassment. The stains and spots are obvious, and they look really disgusting.

So what can I do to fix this problem? I have already tried DIY solutions from the internet. But none of them made a visible difference. I also tried to scratch my teeth, but I heard it would damage the enamel. So I'm looking for a bleaching solution that will work.

I would like to hear your opinion. Which will be best if long-lasting whitening is my main concern and not money?