Temporomandibular disorder(s) (TMD), or temporomandibular joint syndrome, is the most common cause of facial pain after toothache. In the past, many physicians called this condition TMJ disease or TMJ syndrome. TMD was previously known under the eponymous title of Costen syndrome, after Dr. James Costen, who elucidated many aspects of the syndrome as it relates to dental malocclusion. Today, a much more comprehensive view of this condition exists, and the term temporomandibular disorder (TMD) is the preferred term according to the American Academy of Orofacial Pain (AAOP) and most other groups who sponsor studies into its origins and treatment.
Interestingly, the National Institute of Dental and Craniofacial Research (NIDCR) puts TMJ and TMD together and refers to them as temporomandibular joint disorder (TMJD). However, the term TMD is preferred and used in this article.