Abstract
Purpose: A prospective cohort study was designed to determine the relationship between muscle pain and the parameters of masticatory muscle diagnostic tests. Masticatory muscle electromyograms (EMG) and pressure pain thresholds (PPT) were included as parameters to be analyzed.
Materials and Methods: One hundred ninety-six healthy volunteers (134 males, 62 females, mean age of 20.0±2.1 years old) were assessed by surface EMG and PPT on both sides of the masseter muscle. The EMGs were recorded during a maximum sustained contraction. All the subjects were asked to fill out a questionnaire in the initial year of the study regarding their general and oral health conditions. The second clinical examination took place 2.5 years later to determine the incidence of masticatory muscle pain. The PPT and EMG parameters were then evaluated to discover their relationship to the incidence of muscle pain by calculating the relative risk of pain.
Results: Out of 196 patients, seven subjects experienced masseter muscle pain 2.5 years later. Although the integrated EMG values did not show a significant change in the relative risk for pain, the PPT values and EMG power spectral changing patterns displayed a high risk for pain.
Conclusion: Since a low level of PPT and abnormalities in the EMG power spectral changing pattern indicated the possibility of future masseter muscle pain, pain sensitivity can be confirmed as one of the contributing factors to masseter muscle pain.
