Ask a dentist if your whitening toothpaste whitens your teeth and you’ll get a qualified meh. Most whitening toothpastes are full of tiny abrasives called Diotoms, handy organisms that brush away surface stains. But to restore off-colour teeth to virgin-whiteness, you need to go deeper, to the enamel layer.
The most effective substance for that is carbamide peroxide gel. The over-the-counter stuff that has this usually doesn’t have it in high enough concentration to be fully effective. You need a custom-made dental tray, and a gel with 10 per cent peroxide (and professional assistance) to make those pearly whites white.