Try to get ahold of some Thieves oil or Thieves oil toothpaste from this placehttp://www.youngliving.us/US/products.asp
I don't know if you can order it directly or have to go through a distributor. I have not used it yet (just ordered some from someone I know) but I know several people (not distributors or related to the company) that have raved about it. It was just the topic of a lot of conversation on a local natural parenting board. Apparently, people have shocked their dentists w/ the results. You use the toothpaste and/ or dab on the oil to the affected tooth. Good luck!
There is also a thread somewhere in the dental forum on healing cavities w/ nutrition--good info but quite involved!