April 13, 2010
Many people with a chronic temporomandibular disorder (TMD) say they struggle to control the pain and discomfort. One of the primary reasons is TMJ disorders, which typically affect more females than males, arise from a highly complex biological interplay that involves myriad factors. These factors range from the intricacies of chronic pain transmission and its likely rewiring and amplification en route to the brain to the complicating presence of other painful conditions, such as fibromyalgia and irritable bowel syndrome, which possibly mask or modify the symptoms of the TMJ problem.
With so many variables on the table, some researchers have suggested the best scientific entry point to examine and ultimately identify the elements of a TMJ disorder is during its earliest stages, before the full-blown complexity of advanced disease clouds the investigative picture. Although once difficult to conduct for a variety of technical reasons, a so-called natural history study is now scientifically viable. This led five years ago to the launch of the NIDCR-supported Orofacial Pain: Prospective Evaluation and Risk Assessment project, or OPPERA. It marks the first-ever large, prospective clinical study to identify risk factors that contribute to the development of a TMJ disorder. A prospective study looks forward in time, tracking volunteers over several months or years to monitor the onset and natural course of a disease.
In the February issue of the Clinical Journal of Pain, NIDCR grantees from the University of North Carolina and colleagues publish results from a separate pilot natural history study that helped lay the scientific groundwork for the larger OPPERA trial. The paper presents three-year data from a large cohort of women between the ages of 18 and 34 years who began the study with no history of TMD.
The researchers found that 16 of the study’s 266 participants developed a TMD condition, totaling six percent of enrollees. They note that this percentage is comparable to the three-year results of another previous longitudinal study. The researchers also found that the 16 women who developed TMD also self-reported significant increases in headaches, muscle, and other pain. Interestingly, these women also collectively reported at baseline more experience with joint, back, chest, and menstrual pain compared to other participants.
“These findings are in agreement with various case-control studies which have suggested that it seems inappropriate to consider TMD in isolation,” the authors concluded. “Rather, regional and widespread chronic pain conditions represent ‘overlapping’ conditions, and should be considered as part of a ‘continuum’ than distinct entities with distinct etiologies. That being said, there are also other risk factors unique to the development of TMD such as bruxism [teeth grinding], history of facial trauma, and third-molar extraction, which may not present as significant risk factors for the development of pain in other areas of the body.”
- Development of Temporomandibular Disorders is Associated With Greater Bodily Pain Experience. Feng P, Smith S, Bhalang K, Slade GD, Maixner W. Clinc J Pain 2010 February 26;2:116-120.