UB Dental Researchers Collaborate on $5 Million Study to Redefine Temporomandibular Disorder

BUFFALO, N.Y. -- An estimated 5-10 percent of the U.S. population suffers from temporomandibular disorders (TMD), experiencing debilitating pain that can destroy the quality of life.

TMD symptoms include pain or discomfort in or around the ear, jaw joint, and/or muscles of the jaw, face, temples and neck on one or both sides. The pain may arise suddenly or progress over months to years with intermittent frequency and intensity.

Diagnosing the disorder is fraught with problems. TMD usually involves more than a single symptom, rarely has a single cause, and frequently involves multiple factors, including behavioral and emotional responses. Lacking a firm set of diagnostic tools, physicians and dentists often depend on their individual judgment to decide if a patient does or does not have the disorder.

Now the University at Buffalo School of Dental Medicine is collaborating with two other major universities on a joint $5 million project to establish valid and reliable TMD criteria clinicians can use in their practices to diagnose and treat these disorders.

At UB the work will be based in the Center for the Study of Pain in the UB School of Dental Medicine, directed by Richard Ohrbach, D.D.S., Ph.D., associate professor of oral diagnostic sciences and UB's principal investigator on the study. The other two partners are the University of Minnesota, the lead center on the study, and the University of Washington.

"This research study represents the most comprehensive examination of diagnostic methods and concepts yet conducted for any chronic pain disorder," Ohrbach said. "This is due in part to the significance of TMD in the population and the urgent need to provide more valid and more cost effective diagnosis for those individuals, so they can receive better treatment."

"TMD is difficult to diagnose because there is no single measure that provides objective independent evidence of this disorder," Ohrbach said. "In this regard, it resembles the diagnosis of depression. There are no reliable physical signs. That's what makes diagnosis so hard. For example, change in the temporomandibular joint structure is not necessarily related to the pain." (TMD disorders often are incorrectly referred to as "TMJ" because the pain often is centered in that joint.)

In an effort to establish universal, definitive standards for pinpointing TMD, study investigators will revalidate existing criteria and assess the validity of potential new indicators of TMD through blinded clinical examinations, mental-status assessments, two types of imaging scans, and fluid and tissue analysis.

Initially, two examiners from each school will be certified for reliability at the University at Minnesota. Each center then will recruit study participants and enroll them in one of eight subgroups, based on the type of pain they report. A total of 230 participants will be recruited at the UB center.

Both examiners will assess all study participants at their site; however, one examiner will not know who are TMD patients and who are healthy controls. All subjects also will undergo panoramic screening, magnetic resonance imaging (MRI) and computed tomography (CT) scans.

Diagnoses made by both examiners will be compared with each other and with a consensus diagnosis of an expert panel based on the patient's history and scans.

Researchers at UB and the University at Washington also will administer a mental-status questionnaire to a subgroup of study participants, collect patients' self-reports of pain and compare these data with the results of highly structured psychiatric interviews used worldwide by the World Health Organization. These assessments will allow researchers to test the reliability of self-reported data regarding a person's functional status. The results will help define how pain influences people and how they respond to it, Ohrbach said.

Researchers at the University at Minnesota will draw fluid from the temporomandibular joint and do muscle biopsies in a subgroup to look for physical markers of pain.

All methods and tools of diagnosis will be evaluated to determine which are most revealing, hold up over time and are cost-effective, Ohrbach said.

"The importance of this research lies in the refinement of our diagnostic procedures," Ohrbach said. "It will clarify greatly the nature of the particular problem a person presents with, eliminate unnecessary diagnostic procedures that have no validity, and facilitate basic research and clinical trials worldwide through our international consortium for TMD research."

The study is funded by National Institute of Dental and Craniofacial Research. UB's portion of the study will exceed $1 million over four years.