Anyone have experience with over-the-counter tooth-whitening products?

I am considering using an over-the-counter tooth-whitening product. I usually try to use all-natural products, and avoid toxic ingredients. I am wondering if anyone has a recommendation for an easy, inexpensive, safe method of whitening teeth. I asked my dentist if the over-the-counter products at the drugstore were natural and she said no problem – but then again, her practice is always trying to convince me to get x-rays every single visit – so I’m not sure we are on the same page when it comes to what is natural/healthy. Thoughts?