Temporomandibular disorders (TMD) — conditions affecting the jaw joint, chewing muscles, and surrounding tissues — affect between 5 and 25 percent of U.S. adults at some point in their lives, according to the National Institutes of Health, with more than 10 million Americans experiencing jaw joint (TMJ) pain each year. These disorders can cause chronic pain, limited jaw movement, headaches, facial pain, and clicking or popping in the jaw. Despite how common they are, researchers still don't fully understand why some patients develop pain that persists long after it starts.
A new grant from the National Institute of Dental and Craniofacial Research will help a University of Alabama at Birmingham researcher pursue answers to those longstanding questions.
Yu Shin Kim, M.S., Ph.D., Presidential Faculty Scholar Professor in the Department of Endodontics at the UAB School of Dentistry, has received a five-year, $2.2 million R01 award to study the peripheral mechanisms of TMJ pain. The project, "Peripheral Mechanisms of Temporomandibular Joint Pain," will run through 2031.
"Improved, mechanism-based therapies are needed to reduce the enormous toll of TMJ pain on individuals and public health," Kim said.
Much is already known about the factors linked to TMD, but a central question remains unanswered: what keeps the pain going after the original cause is gone.
"Current understanding of how chronic TMD is generated is still obscure," Kim said. "We do not know what causes TMJ pain that continues after the original stimulus is no longer present. We still do not understand the nature of facial pain in TMD, and it remains unclear what particular factors or molecules lead to chronic and persistent jaw joint and muscle pain."
To find out, Kim and his team will study how sensory nerve cells behave in both healthy and disease conditions, using advanced imaging that lets them observe the activity of several thousand nerve cells at once — a scale of detail that has been difficult to achieve in TMJ pain research until now.
"This study should facilitate our understanding of TMJ pain modulation and eventually lead to mechanism-based therapies and more targeted therapeutic advances," Kim said. "By addressing these questions, the work will help identify better therapeutic targets that may provide effective chronic TMJ pain relief."
The award also caps a long road to get here.
"We developed this project about 10 years ago but could not initiate the study because of funding limitations," Kim said. "We now have the opportunity to perform this exciting research and test our hypothesis regarding the molecular and cellular mechanisms of TMJ pain."
Kim hopes the project will clarify how TMJ pain develops and persists and lay the groundwork for future treatments that improve quality of life for the millions of Americans living with TMD.