Sleep bruxism (SB), primarily involving rhythmic grinding of the teeth during sleep, has been advanced as a causal or maintenance factor for a variety of orofacial problems, including temporomandibular disorders (TMD). Since laboratory polysomnographic (PSG) assessment is extremely expensive and time-consuming, most research testing this belief has relied on patient self-report of SB. The current case-control study examined the accuracy of those self-reports relative to laboratory-based PSG assessment of SB in a large sample of women suffering from chronic myofascial TMD (n=124) and a demographically matched control group without TMD (n=46). A clinical research coordinator administered a structured questionnaire to assess self-reported SB. Participants then spent two consecutive nights in a sleep laboratory. Audiovisual and electromyographic data from the second night were scored to assess whether participants met criteria for presence of 2 or more (2+) rhythmic masticatory muscle activity episodes accompanied by grinding sounds, moderate SB, or severe SB, using previously validated research scoring standards. Contingency tables were constructed to assess positive and negative predictive values, sensitivity and specificity, and 95% confidence intervals surrounding the point estimates. Results showed that self-report significantly predicted 2+ grinding sounds during sleep for TMD cases. However, self-reported SB failed to significantly predict presence or absence of either moderate or severe SB as assessed by PSG, for both cases and controls. These data show that self-report of tooth grinding awareness is highly unlikely to be a valid indicator of true SB. Studies relying on self-report to assess SB must be viewed with extreme caution.

Despite theoretical speculation and strong clinical belief, recent research using laboratory polysomnographic (PSG) recording has provided new evidence that frequency of sleep bruxism (SB) masseter muscle events, including grinding or clenching of the teeth during sleep, is not increased for women with chronic myofascial temporomandibular disorder (TMD). The current case-control study compares a large sample of women suffering from chronic myofascial TMD (n=124) with a demographically matched control group without TMD (n=46) on sleep background electromyography (EMG) during a laboratory PSG study. Background EMG activity was measured as EMG root mean square (RMS) from the right masseter muscle after lights out. Sleep background EMG activity was defined as EMG RMS remaining after activity attributable to SB, other orofacial activity, other oromotor activity and movement artifacts were removed. Results indicated that median background EMG during these non SB-event periods was significantly higher (p<.01) for women with myofascial TMD (median=3.31 μV and mean=4.98 μV) than for control women (median=2.83 μV and mean=3.88 μV) with median activity in 72% of cases exceeding control activity. Moreover, for TMD cases, background EMG was positively associated and SB event-related EMG was negatively associated with pain intensity ratings (0–10 numerical scale) on post sleep waking. These data provide the foundation for a new focus on small, but persistent, elevations in sleep EMG activity over the course of the night as a mechanism of pain induction or maintenance.

Study Objectives: Temporomandibular pain disorders (TMD) and myofascial pain were linked to increased prevalence of insomnia and obstructive sleep apnea (OSA) on clinical grounds. However, the literature lacks an accurate polysomnographic (PSG) characterization of sleep abnormalities associated with TMD, given that prior studies included small or uncontrolled samples of TMD patients. The present investigation aims to objectively evaluate measures of sleep and respiratory disturbance in a large representative sample of TMD cases in comparison with matched controls. Methods: Sleep, respiration, and limb movements were measured using a 2-night attended PSG protocol in 170 women-124 TMD cases with myofascial pain and 46 demographically matched controls. The second night data were compared between the groups using ANCOVAs. In TMD cases, the relationship between pain ratings and sleep parameters was analyzed using multiple regressions. Results: In comparison to healthy controls, TMD cased evidenced a signifi cant increase in stage N1 sleep (12.2% ± 7.6% vs. 9.2% ± 5.0%, p = 0.03), which was only mild relative to normative values. TMD cases also demonstrated mild but signifi cant elevations in arousals associated with all types of respiratory events (6.0/h ± 6.1 vs. 3.5/h ± 3. S C I E N T I F I C I N V E S T I G A T I O N ST emporomandibular disorders (TMD), most often characterized by painful musculoskeletal signs and symptoms in the masticatory region, is a pain syndrome estimated to affect approximately 5% to 15% of the population, predominantly women.1-4 Subjective sleep disturbance has been consistently reported in TMD patients. 5,6 Two earlier polysomnographic (PSG) studies failed to demonstrate objective differences in sleep or respiratory measures between TMD cases with myofascial pain and control participants free from myofascial pain and signs of TMD; however, the small sample sizes and restrictive selection criteria limit their interpretability. 7,8 A recent investigation employing PSG recordings and clinical sleep interviews in an uncontrolled sample of TMD cases showed that TMD is associated with primary sleep disorders, such as insomnia and obstructive sleep apnea (OSA): nearly 36% of TMD cases met diagnostic criteria for insomnia, and over 28% met criteria for OSA. 9 In the same sample of TMD cases, sleep effi ciency on PSG was directly related to a measure of pain threshold, suggesting an association between pain and sleep disturbance in TMD.9,10 Additionally, a high prevalence of TMD was reported in clinical patients with mild to moderate OSA referred for a clinical dental evaluation, lending further support to the association between TMD and OSA.11 It was BRIEF SUMMARYCurrent Knowledge/Study Rationale: A relationship between temporomandibular pain disorders (TMD) and sleep and respiratory disturbance has been suggested; however, large-scale controlled polysomnographic studies are lacking. The present investigation used two-night polysomnography to measure sleep architecture and respiration in a large...

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Background Many dentists believe that sleep bruxism (SB) is a pathogenic factor in myofascial temporomandibular disorder (TMD), but almost all supportive data rely on patients’ self-reports rather than on direct observation. Methods The authors administered a structured self-report interview to determine whether a large and well-characterized sample of patients with myofascial TMD (124 women) experienced SB more often than did matched control participants (46 women). The authors then used data from a two-night laboratory-based polysomnographic (PSG) study to determine whether the case participants exhibited more SB than the control participants. Results The results of independent sample t tests and χ2 analyses showed that, although self-reported rates of SB were significantly higher in case participants (55.3 percent) than in control participants (15.2 percent), PSG-based measures showed much lower and statistically similar rates of SB in the two groups (9.7 percent and 10.9 percent, respectively). Grinding noises were common in both case participants (59.7 percent) and control participants (78.3 percent). Conclusions Most case participants did not exhibit SB, and the common belief that SB is a sufficient explanation for myofascial TMD should be abandoned. Clinical Implications Although other reasons to consider treating SB may exist, misplaced concern about SB’s sustaining or exacerbating a chronic myofascial TMD condition should not be used to justify SB treatment.