I have super-sensitive teeth, always have. If I eat anything too hot or too cold or too sugary, I get the kind of pain you feel when you chew on tinfoil with metal fillings (which I don't recommend). The only thing that helps keep the pain at bay is toothpaste for sensitive teeth.
For years, I was under the impression that Sensodyne toothpaste was the only sensitivity toothpaste that would work for my teeth. Someone had told me that the others didn't work as well, and I just stuck with that. I think even my dental hygienist said she only recommended Sensodyne.
Imagine my surprise then, when one day, oh, 15 years later, when I actually looked at the ingredients on all the sensitivity toothpastes. The ingredients are exactly the same! I'd been paying close to $6.00 a tube for something I could get a whole lot cheaper! Even better, I was looking in the dollar store the other day, and looked at their sensitivity toothpaste. Yup, Potassium Nitrate 5%. Same as the rest!
I bought it and started using it when I ran out of my very-expensive Sensodyne (which, by the way, never goes on sale; believe me, I've looked. Plus, I requested a free sample and coupon online once and never got them). It works great! So learn from my decades-long mistake and get yourself some good old dollar-store toothpaste.
On a side note, I found this article on Consumer Reports interesting. It found that the cheapest toothpaste for whitening (Ultra Brite) turned out to have the best results of any of the major-brand toothpastes they tested. The Straight Dope further emphasizes this point:
"Price mostly reflects the grandiosity of manufacturer claims, not product quality. Remember pricey Rembrandt? It got some of CR's worst ratings. Dirt-cheap Ultra Brite, on the other hand, got some of the best."Food for thought.
For more "Why didn't I think of that?" ideas, head on over to Rocks in My Dryer.