Fruitarians think so. They don't eat animal products, and they only eat parts of plants they can take without killing the plant. As such, they eat a lot of fruit, and therefore probably have bad teeth.
I used to be vegan. I got sick because it's expensive, and I couln't afford the food needed to sustain myself. I'm thinking about going back, now that I have a little more money.
If you worry about things like this though, you'll go mad. You can link any two things together.