I am not licensed in NC and can offer you general advice. The risk associated with not giving antibiotic as a preventive measure is that you might get an infection. It sounds like you did not contract an infection and if that is true you have no damages. Without damages there is nothing for a jury to give you compensation for. In the end, you would spend money to recover no money, but only a piece of paper that says that the dentist made a technical mistake. You may consider reporting the dentist to the local dental society.
Medical malpractice is about what actually happened and not what could have happened. This can seem unfair when a doctor, or dentist, is careless and fails to take certain precautions, and puts you at risk. If your gums hurt because of an infection that was caused by the dentist's failure to take reasonable precautions, you may be able to establish malpractice. However, unless there is significant or permanent injury, it probably wouldn't be worth pursuing. Make sure you get the treatment you need for the pain you're still experiencing.
Sign up to receive a 3-part series of useful information and advice about personal injury law.