Yes, you can sue your dentist in small claims court. And yes, the failure to inform a patient about the risks and consequences of treatment can form the basis of a claim. I recommend that you at least speak with an attorney before filing the suit, even if you have to pay him or her for their time. They should be able to give you some pointers which will make it more likely that you'll win and keep you from having to hire expensive experts.
I wish you the best of luck.
Clancy Law Offices
Sign up to receive a 3-part series of useful information and advice about personal injury law.