Guide to evaluation of permanent impairment of the temporomandibular joint. American Academy of Head, Neck and Facial Pain; American Academy of Orofacial Pain; American Academy of Pain Management; American College of Prosthodontists; American Equilibration Society and Society of Occlusal Studies; American Society of Maxillofacial Surgeons; American Society of Temporomandibular Joint Surgeons; International College of Cranio-mandibular Orthopedics; Society for Occlusal Studies.