First, get an independent medical opinion about the injury, such as from another dentist or an ENT specialist. IF there is a long-lasting or permanent injury, then you may have a viable malpractice case, based on the dentist either being negligent (careless) in striking the never and/or negligent in not warning you of the risk. In that event, speak with a personal injury attorney (many provide a free initial consultation; you can ask about this before making the appointment) to evaluate the strength of your case and what it might be worth, since every malpractice case is different and depends on its own unique facts.If there is no long lasting or permanent injury and it's just like a few days longer to resolve than the dentist thought, there's no point in suing: the compensation for a few days of numbness is far, far less than the cost of a malpractice lawsuit.