This will not be what you want to hear, but it's important that you understand how the law works in this kind of situation. When it comes to decisions about who they will serve doctor and dentist offices are treated under the law as businesses like any other. And businesses have the right to deny serving any person for any reason except for a few reasons prohibited by law.
The Americans with Disabilities Act (ADA) does not apply here. Your tooth, though painful, is not a disability under the Act. Even if it was, what the ADA says is that the business cannot discriminate against you because of the disability. But the dentist did not refuse to see you because you had a painful tooth. The dentist refused to see you because he did not want to rely on the records you provided and because of your attitude. Perhaps your attitude would not have aggravated most people, but that doesn't really matter. The refusal was not because of a disability nor, so far as I can see from what you wrote, was the refusal based on any other prohibited reason (like your race, religion, sex, etc). As a result, the dentist was within his legal rights to refuse to treat you. Thus, if you sue the dentist over this you will lose. And you might even get hit with sanctions for filing a frivolous claim.
Now perhaps some facts that you didn't mention might change the outcome here. So on the off chance you left something out you might want to consult a lawyer in your area to see if you might have something to pursue. Just don't get your hopes up much on that. Chances are good you'll hear much the same thing from the lawyers you consult.

