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Sensitive teeth are caused by the wearing away of tooth enamel. Dentists say this is caused by things like acidic food, chewing ice, brushing too hard, and baking soda. While the former may be right, the baking soda part is incredibly wrong. It's possible that some baking soda toothpastes can cause this, but baking soda itself is relatively harmless. Whitening toothpastes are a different story however.

There is something called an "RDA" or Relative Dentin Abrasivity. This is an important number and I think the fact that it's not commonly advertised on packaging is just another example of industry misleading it's consumers. Toothpastes with a higher RDA are usually better at cleaning gunk and stains off the teeth and whitening the teeth, while they are also good at cleaning off the enamel. Lower RDA toothpaste can be just as good at cleaning the teeth, but maybe not as good at taking off any stains.

However, the irony of it is, whitening your teeth can't even help if you don't have any tooth enamel because the second layer of your teeth is dentin, which is naturally not white and virtually impossible to whiten. For more info on that, check here.

For a list of the RDA of some common toothpastes check here. However, the RDA of a toothpaste can be hard to get ahold of, especially with all the different varieties. The RDA of a gel or paste or a special variety or taste of toothpaste can be different than the normal. Different sources may show different RDA values for the same toothpaste as well(for example). Which one is right? Who knows? I think arm and hammer publishes the RDA of most, if not all of their toothpaste so those can be trusted. They are also some of the lowest. Baking soda itself has an RDA of 7. Only 3 above plain water. If you check both links the difference in the RDA of AIM toothpaste is enormous and I think that might be a difference in gel and paste. I'm guessing paste would be the lower one but one or both of them could just be plain wrong.
The rda value is especially important for someone who uses an electric toothbrush.

Also, make sure you get soft toothbrushes. If they fray, you're brushing too hard.
Carbonate beverages, fruit, fruit juice, lemonade, and sports drinks are some of the harshest foods. The sugar content doesn't help either. So, if you want healthy teeth drink water, use low RDA toothpaste, a soft toothbrush, and don't brush too hard.