Dr. Alan Glaros and colleagues presented a provocative article in April JADA, "The Role of Parafunctions, Emotions and Stress in Predicting Facial Pain." The article utilizes ecological momentary assessment (EMA) to assess daytime parafunctions.
Until this article was published, researchers troubled by the questionable validity of self-reported bruxism were forced to consider the conduct of a labor-intensive sleep study using electromyography (EMG) with audiovisual monitoring to differentiate bruxism from other motor activities. Even this method would not directly provide data on daytime bruxism. Thus, the potential for EMA to provide a way to assess daytime bruxism and, consequently, the validity of a proposed relationship between daytime bruxism and facial pain, is intriguing.
Nevertheless, one major limitation to the use of EMA should be acknowledged: although EMA has shown great promise for the assessment of pain, the validity of EMA for the assessment of bruxism is unknown. The method needs to be validated against a gold standard, such as EMG or actigraphy of jaw activity. The authors carefully discuss their assessment of "parafunctions," rather than assuming that their measure assesses bruxism specifically.
Yet, this distinction may ultimately prove critical. Until we have data on the validity of the EMA method for assessment of daytime bruxism, especially its ability to differentiate clenching from other parafunctions, it cannot yet be considered any more than an improved variety of self-report. While EMA avoids problems of longer-term recall inherent in standard self-report methods, it still is potentially limited by a variety of other biases in self-reported data.
For example, a potential confounding influence in EMA assessment of bruxism is that when participants are paged, "reactivity of measurement" actually changes the phenomenon being measured, leading participants to alter their extent of tooth contact. Thus, bruxism may vary with attention. As another example, because participants in this study were prompted to report simultaneously on pain, tension, stress and severity of tooth contact, they could have inferred that they "must" have been bruxing, if they are experiencing pain, and if they believe that there is a relationship between bruxism and facial pain.
We previously have shown in JADA1 that patients’ beliefs about whether they brux are heavily influenced by what their dentist tells them. Whatever the cause of the discrepancy, previous research has shown low levels of concordance between short-term self-reports of facial muscle activity and daytime masseter EMG activity in TMD patients,2 perhaps revealing the inevitable limitations of self-report to which EMA is intrinsically tied.
Thus, although we are intrigued by this first published use of EMA to try to assess daytime parafunctions, we wish to caution JADA readers: EMA of self-reported tooth contact is not an objective measure of daytime bruxism. Until EMA can be shown to be a valid tool for the assessment of daytime bruxism, we remain concerned that the authors’ conclusions about the relationship between parafunctional behaviors and orofacial pain may not be justified.
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