The Etiology of Temporomandibular Disorders

Temporomandibular disorder (TMD) is an umbrella term referring to the dysfunction and pathologic conditions of the musculoskeletal and neuromuscular elements of the temporomandibular joint (TMJ), masticatory muscles, and adjacent structures. The most common clinical manifestations of TMD are masticatory muscle pain, limited range of mouth opening, noise from the TMJ, and chronic myofascial pain. Almost every discipline in dentistry played some role in the development of this topic. Each dental specialty looked at TMD from their own perspective and biases using their own terminology to describe the problems and suggest their treatment plans. The etiology of TMD has always been a controversial topic and has evolved over the last few years. Recent research from the fields of behavioral sciences, psychology, genetics, pain pathophysiology, neurophysiology, and endocrinology has significantly revolutionized our understanding of TMDs and how they should be managed. TMDs are no longer believed to be caused by a single factor only with a gradual shift from the dental-based and mechanical model to a biopsychosocial medical model. In this chapter, we will discuss the role of the different factors that are believed to be involved in the etiology of TMD.