Mcleans whitening toothpaste will get them pearly and it's a lot cheaper than a dentists. Brush twice a day; don't rinse after and go as long as you can before eating or drinking. You'll see the difference after only a few days.
I've no affiliation with them; but am open to bribes! :-)
The Sock
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The world is in haste and nears its end – Wulfstan II Archbishop of York 1014.