Best bet is to get a new dentist. Avvo has a terrific "find a lawyer" tool to find a top-rated aggressive Avvo attorney with a low contingency fee. Good luck.
You may be able to more than get your money back. It appears that you have an ill-fitting bridge which is indicative of malpractice. Consult with a local experienced dental malpractice attorney to see what can be done and do not return to that dentist, find a new one ASAP.
You should be able to. Contact the dentist and ask. If the dentist refuses, file a complaint with the local dental board. If that does not work, then consult with a lawyer.
As a business matter, you may be able to go in and successfully get the dentist to replace it. You have posted this question on a website to inquire about a malpractice angle. As a malpractice claim, you wouldn't have much leverage. The value of the claim is too de minimus to justify legal action, which can be very costly. Thus, your legal rights are tiny. I would just go in and politely try to get it fixed.
Mr. Stewart's answer is the only sensible angle here. Several of the other contributors here suggest seeking counsel from an Avvo attorney using the "find an attorney tool." They make the same suggestion to each question I have read. The only addition I might recommend is that you get a second opinion of your condition from another dentist. You could consult with the first dentist, explaining that you have been spending a lot of time on this matter without her being able to resolve the issue. If another dentist is able to repair the tooth and prevent the mishaps you can request the first dentist to pay the the added cost.
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