Effect of experimental temporomandibular disorder pain on sleep bruxism: a pilot study in males.

OBJECTIVES: Sleep bruxism (SB) is considered to play an important role in the provocation of temporomandibular disorder (TMD) pain. However, clinical studies investigating this relation yielded contradictory results. These contradictory results can, at least in part, be explained by a possible influence of TMD pain on SB activity. The aim of this experimental study was to assess the effect of TMD pain on SB. MATERIALS AND METHODS: Nine male participants with clinical signs of SB underwent two subsequent baseline ambulatory polysomnographic (PSG) recordings before undergoing an experimental pain provocation protocol. Thirty-two hours after the pain provocation part a third ambulatory PSG recording was obtained to study the effect of pain on SB. RESULTS: Decrease for all bruxism parameters was found between the recording after the provocation part and the second baseline recording. CONCLUSIONS: Experimentally induced TMD pain causes a reduction in SB activity in healthy individuals. CLINICAL RELEVANCE: A reduction in sleep bruxism activity was recorded in all participants who experienced jaw-muscle pain. This is in line with the pain adaptation model. It supports the negative association between sleep bruxism and jaw muscle pain reported by numerous polysomnographic studies.

No Dose-Response Association Between Self-Reported Bruxism and Pain-Related Temporomandibular Disorders: A Retrospective Study.

AIMS: To investigate whether a dose-response relationship exists between the intensity of pain-related temporomandibular disorders (TMDs) and the amount of self-reported bruxism activities in a group of TMD pain patients. METHODS: A total of 768 patients referred to a specialized clinic for complaints of orofacial pain and dysfunction were initially enrolled in the study. Of these patients, 293 who were diagnosed with at least one type of pain-related TMD according to the Diagnostic Criteria for Temporomandibular Disorders were selected. The questionnaire-based reports of TMD pain intensity, as assessed by an 11-point numeric rating scale (NRS), were subsequently compared to the reports of sleep bruxism (single question; 5-point Likert scale) and awake bruxism (mean score of six questions; 5-point Likert scale). Spearman correlations were used to assess associations, and possible confounding effects of depression, somatic symptoms, and anxiety were taken into account. RESULTS: Spearman correlation tests provided no significant correlation between the amount of self-reported sleep bruxism and TMD pain intensity. On the other hand, the amount of awake bruxism was positively correlated with the intensity of TMD pain; however, the latter correlation was lost when the model was controlled for the effects of depression. CONCLUSION: The assumption that there is a dose-response gradient association between bruxism and TMD pain, reflected in more bruxism leading to more overloading and thus to more pain, could not be justified.

Interepisode Sleep Bruxism Intervals and Myofascial Face Pain.

Study Objectives: Sleep bruxism (SB) is considered as a possible etiological factor for temporomandibular disorder (TMD) pain. However, polysomnographic (PSG) studies, which are current "gold standard" diagnostic approach to SB, failed to prove an association between SB and TMD. A possible explanation could be that PSG studies have considered only limited characteristics of SB activity: the number of SB events per hour and, sometimes, the total duration of SB per night. According to the sports sciences literature, lack of adequate rest time between muscle activities leads to muscle overloading and pain. Therefore, the aim of this study was to determine whether the intervals between bruxism events differ between patients with and without TMD pain. Methods: Two groups of female volunteers were recruited: myofascial TMD pain group (n=124) and non-TMD control group (n=46). From these groups, we selected 86 (69%) case participants and 37 (80%) controls who had at least two SB episodes per night based on PSG recordings. A linear mixed model was used to compare case and control groups over the repeated observations of interepisode intervals. Results: The duration of interepisode intervals was statistically similar in the case (mean [standard deviation {SD}] 1137.7 [1975.8] seconds)] and control (mean [SD] 1192.0 [1972.0] seconds) groups. There were also a similar number of SB episodes per hour and a total duration of SB episodes in both groups. Conclusions: The current data fail to support the idea that TMD pain can be explained by increasing number of SB episodes per hour of sleep or decreasing the time between SB events.

Are Pain-Related Temporomandibular Disorders the Product of an Interaction Between Psychological Factors and Self-Reported Bruxism?

AIMS: To investigate whether pain-related temporomandibular disorders (TMD) are the product of an interaction between psychological factors and self-reported bruxism activities. METHODS: Patients referred to a specialized clinic for complaints of orofacial pain and dysfunction completed a digital questionnaire prior to the first clinical visit. The patient sample was then split into a case group consisting of 268 patients diagnosed with TMD pain according to the Diagnostic Criteria for Temporomandibular Disorders (85.8% women; mean ± standard deviation [SD] age = 40.1 ± 14.5 years) and a control group consisting of 254 patients without any pain in the orofacial area (50.8% women; 46.9 ± 13.6 years). The possible moderating roles of six psychological factors (depression, somatic symptoms, anxiety, stress, optimism, and prior psychological treatment) on the relationship between self-reported bruxism and the clinical presence of TMD pain were examined. RESULTS: Patients with TMD pain reported significantly more bruxism than patients without any report of orofacial pain. Furthermore, bruxism intensity was associated with a variety of psychological factors; however, there were no significant interactions between any of the psychological factors and bruxism with respect to the clinical presence of TMD pain. CONCLUSION: These findings do not support the view that the effect of bruxism on TMD pain is stronger in patients who experience higher levels of psychological distress compared to those with lower levels of distress.