I tried mixing coconut oil and baking soda, which is a common toothpaste recipe, and it worked rather well, but the consistency freaked me out.
The oil was very slimy on my teeth and there was none of the usual toothpaste foam. The taste was very odd too. I love the smell of coconut oil, and when it's combined in baking and certain dishes the taste is great too. But when mixed with baking soda, the taste was less than pleasant. Next time I'll try adding mint extract or something! :)
When I find a better recipe I'll share it!