Sorry to hear about your dental problems.Malpractice is based on negligence.  The applicable statute of limitations in a medical malpractice case will determine whether or not it is too late to file your lawsuit against the dentist.  Given the fact that the malpractice occurred over 30 years ago, it is probably too late to file your lawsuit; however, in a malpractice case, the statute of limitations does not start running until you have become aware of the condition.  Therefore, it would be advisable to discuss the applicable statute of limitations with a medical malpractice attorney.