Alan Glaros, Ph.D.
My work is primarily focused on the behavioral factors associated with myofascial and joint pain in individuals diagnosed with temporomandibular disorders (TMJD). In my lab, we use psychophysiological techniques and experience sampling methods to address the degree to which parafunctional activities, particularly tooth contact, are associated with TMJD.
We have carried out a number of studies in which we ask healthy, non-TMJD participants to clench their teeth moderately for approximately 20 minutes per day, up to eight days. The results for the studies carried out thus far have been consistent: Deliberate moderate clenching performed 20 minutes per day increases pain in those without any sign or symptom of TMJD. Approximately 25% of those who engage in experimental clenching develop symptoms sufficiently intense that they are (temporarily) diagnosed with TMJD. These studies have shown that experimental clenching increases pain and can produce symptoms of TMJD.
We have also examined the hypothesis that actual TMJD patients who report pain will have higher levels of clenching than non-TMJD patients. To test this hypothesis, we have used experience sampling methods. In a typical case, we give a TMJD patient a pager. During their waking hours, the pager contacts them approximately every two hours. When that occurs, patients are instructed to fill out a brief questionnaire in which they report on tooth contact, pain levels, and so forth. This study, supported by a grant from the National Institutes of Health, showed that TMJD patients with pain had higher levels of tooth contact, and more intense contact than TMJD patients without pain and normal, non-pain controls.
Taken as a whole, these studies imply that reducing the amount of time and intensity of tooth contact should decrease pain in TMJD patients. To test this idea, we have a number of studies underway that are designed to reduce tooth contact in TMJD patients. In one study, we used a variation of the experience sampling method to remind patients not to clench. This behaviorally-oriented treatment was as effective as standard dental appliances in reducing pain. We are also designing studies to develop a better understanding of the biological changes that occur to the temporomandibular joint and to the muscles of mastication when individuals engage in high levels of unnecessary tooth contact and under non-loaded conditions