Subjective Sleep Quality Deteriorates Before Development of Painful Temporomandibular Disorder

Analysis of risk factors and interactions for pain in temporomandibular disorder: A cross-sectional study

BACKGROUND

Risk factors for temporomandibular disorder (TMD) pain remain unclear.

OBJECTIVES

This study aimed to identify risk factors for TMD pain using a biopsychosocial model and to investigate interactions between potential risk factors-oral behaviours (OBs), psychological factors and sleep quality-and their direct and indirect effects on TMD pain.

METHODS

This was a cross-sectional study of 488 patients with TMDs (422 women; 30.8 ± 9.4 years). Pain was assessed using the Numerical Rating Scale. Demographic, behavioural, psychological and biomedical data were collected through clinical examination, face-to-face interviews and questionnaires. Multiple linear regression analysis was used to identify factors associated with TMD pain. Mediation and moderation analysis were used to evaluate interactions between variables. Significant mediation ('0' not included in the 95% confidence interval (CI)) and moderation (p < .05) effects on TMD pain were identified.

RESULTS

Marital status, diagnosis subgroup, previous medication use, depression and sleep quality were significant risk factors for TMD pain (p < .05). Significant mediation effects were observed as follows: depression and sleep quality mediated the association between OBs and pain; sleep quality mediated the association between somatization, depression, anxiety and pain; and depression mediated the association between sleep quality and pain (all 95% CI did not contain '0').

CONCLUSIONS

(1) Marital status, diagnosis subgroup, previous medication use, depression and sleep quality were associated with TMD pain. (2) OBs can exacerbate pain by promoting depression and reducing sleep quality. Psychological factors and sleep quality can interact to exacerbate pain.

Prevalence and associations of temporomandibular disorders in older Brazilian adults

OBJECTIVE

The objective of the study was to estimate the prevalence of temporomandibular disorders (TMD) and describe associations in a representative sample of community-dwelling older Brazilian adults.

BACKGROUND

TMD cause recurrent or chronic pain and dysfunction with substantial impacts on quality of life, but little is known of their occurrence and associated factors among older adults.

MATERIALS AND METHODS

This was a cross-sectional study using data from the second wave of the Brazilian Longitudinal Study of Aging, a nationally representative sample of older Brazilian adults aged 50 or older. The presence of temporomandibular disorder symptoms was measured by the Fonseca Anamnestic Index. Independent variables included sociodemographic characteristics, general health conditions and self-reported oral health measures. The association between the independent variables and TMD symptoms was evaluated using logistic regression models.

RESULTS

Complete information for the variables of interest was available for 9391 individuals. The overall prevalence of TMD symptoms was 18.0% (95% CI 14.4-22.1). Relative to older adults aged 50-59 those in all age categories had lower odds of TMD symptoms. Individuals with depression, pain, sleep problems and self-reported poor general health had higher odds of reporting TMD symptoms. None of the oral health measures were related to TMD.

CONCLUSION

The prevalence of TMD symptoms among Brazilian older adults is associated with demographic and general health conditions, but not with dentition status.

Influence of psychometric and sleep quality features on painful mechanical sensitivity and pain modulation in patients with temporomandibular disorders

Investigating the collective impact of psychometric properties and sleep quality on pain sensitivity in temporomandibular disorder (TMD) patients could improve clinical management strategies.

OBJECTIVE

Assessing whether combined psychometric properties and sleep quality impact painful mechanical sensitivity and pain modulation in TMD patients.

MATERIALS AND METHODS

A cross-sectional study using secondary data analysis of 77 TMD patients and 101 controls. All participants completed questionnaires characterizing their psychometric profile (anxiety, depression, stress and catastrophizing) and sleep quality, alongside psychophysical tests for painful mechanical sensory (mechanical pain threshold (MPT), pressure pain threshold (PPT), and wind-up ratio (WUR)) and conditioned pain modulation (CPM). Participants were grouped into "High distress" or "Low distress" categories based on psychometric properties and sleep quality using hierarchical cluster and k-means analyses. Multiple linear regression evaluated the influence of TMD, age, and the distress cluster on MPT, WUR, PPT, and CPM in masseter and thenar muscles. Differences were statistically significant when p < 0.05.

RESULTS

The presence of TMD was the strongest predictor of mechanical painful sensitivity in the trigeminal region (MPT[F(3,174) = 51.902;p < .001;R2 = .463]; TMD presence (β = -.682) / PPT[F(3,174) = 15.573;p < .001;R2 = .198] TMD presence (β = -.452), and extra-trigeminal (MPT[F(3,174) = 35.897;p < .001;R2 = .382] TMD (β = -.647) / CPM [F(3,174) = 4.106;p < .05;R2 = .050] TMD presence (β = .197). Furthermore, neither the high distress group nor the low distress group were able to significantly influence the variation of the values of any of the psychophysical variables evaluated (p > .05).

CONCLUSIONS

There is not a significant influence of impairment clusters based on psychological variables and sleep quality on painful mechanical sensitivity and pain modulation, regardless of the presence of TMD.

CLINICAL RELEVANCE

This outcome suggests that psychosocial factors and sleep quality may not play a decisive role in the sensory-discriminative aspect of pain, particularly concerning painful TMD.

Relationship between insomnia and pain in patients with chronic orofacial pain

OBJECTIVE

Few studies have investigated specific associations between insomnia and orofacial pain (OFP). The aim of this cross-sectional study was to examine relationships of insomnia with pain, mental health, and physical health variables among treatment-seeking patients with chronic OFP.

METHODS

OFP diagnosis, demographics, insomnia symptoms, pain intensity, interference, and duration, mental health measures, and number of medical comorbidities were extracted from the medical records of 450 patients receiving an initial appointment at a university-affiliated tertiary OFP clinic. T-tests compared differences between patients with and without insomnia symptomatology, and between patients with different insomnia subtypes (delayed onset/early wakening).

RESULTS

Compared to patients without insomnia, those with elevated insomnia symptomatology (45.1%) reported higher pain intensity (60.70 ± 20.61 vs 44.15 ± 21.69; P < .001) and interference (43.81 ± 29.84 vs 18.40 ± 23.43; P < 0.001), depression/anxiety symptomatology (5.53 ± 3.32 vs 2.72 ± 2.66; P < 0.001), dissatisfaction with life (21.63 ± 6.95 vs 26.50 ± 6.21; P < .001), and number of medical comorbidities (6.72 ± 5.37 vs 4.37 ± 4.60; P < .001). Patients with Sleep Onset Latency insomnia (SOL-insomnia) (N = 76) reported higher pain intensity (t = 3.57; P < 0.001), and pain interference (t = 4.46; P < .001) compared to those without SOL-insomnia. Those with Early Morning Awakening insomnia (EMA-insomnia) (N = 71) did not significantly differ from those without EMA-insomnia on any of the variables. Differences remained significant after adjusting for age, sex, primary OFP diagnosis, and pain intensity.

CONCLUSIONS

Insomnia is associated with pain outcomes and should be appropriately managed when treating patients with chronic OFP.

Presurgical sleep and pain behaviors predict insomnia symptoms and pain after total knee arthroplasty: a 12-month longitudinal, observational study

OBJECTIVE

Up to 40% of individuals who undergo total knee arthroplasty (TKA) experience some degree of pain following surgery. Presurgical insomnia has been identified as a predictor of postsurgical pain; however, modifiable presurgical behaviors related to insomnia have received minimal attention. The objective of the present study was to develop a 2-item sleep and pain behavior scale (SP2) to investigate a maladaptive sleep and pain behavior and is a secondary analysis of a larger, parent study.

METHODS

Patients (N = 109) completed SP2 at baseline and 12 months and questionnaires assessing sleep and pain at baseline (pre-TKA), 6 weeks, 3, 6, and 12 months post-TKA. SP2 demonstrated adequate preliminary psychometric properties.

RESULTS

As hypothesized, even after controlling for baseline insomnia, pain, anxiety and other covariates, baseline SP2 predicted insomnia symptom severity at 6 weeks (β = 2.828), 3 (β = 2.140), 6 (β = 2.962), and 12 months (β = 1.835) and pain at 6 weeks (β = 6.722), 3 (β = 5.536), and 6 months (β = 7.677) post-TKA (P < .05). Insomnia symptoms at 6-weeks post-TKA mediated the effect of presurgical SP2 on pain at 3 (95% CI: 0.024-7.054), 6 (95%CI: 0.495-5.243), and 12 months (95% CI: 0.077-2.684).

CONCLUSIONS

This provides preliminary evidence that patients who cope with pain by retiring to their bed and bedroom have higher rates of post-surgical insomnia and pain and supports efforts to target this maladaptive sleep and pain behavior to reduce postsurgical pain.

The association between sleep quality, depression, anxiety and stress levels, and temporomandibular joint disorders among Turkish dental students during the COVID-19 pandemic

OBJECTIVE

This study aimed to examine the association between sleep quality, depression, anxiety and stress levels, and the frequency of temporomandibular disorders in a sample of Turkish dental students during the COVID-19 pandemic.

METHODS

The current cross-sectional study was conducted with 699 dental university students during the COVID-19 pandemic. Fonseca Anamnestic Index (FAI), Pittsburgh Sleep Quality Index (PSQI), and Depression Anxiety Stress Scale-21 (DASS-21) were used in the present study.

RESULTS

The incidence of temporomandibular joint disorders in the present study was found to be 77.5%. Female students' FAI scores were found to be statistically significantly higher than males (p < 0.05). Additionally, higher depression and anxiety and stress levels caused increased PSQI and FAI scores.

CONCLUSION

During the COVID-19 pandemic, increased temporomandibular joint disorders were observed with increased impaired sleep quality and higher depression, anxiety and stress levels among dental university students.

Association Between Pharmacotherapy and Sleep Quality in Patients with Chronic Orofacial and Chronic Body Pain: A Cross-Sectional Study

Purpose

Sleep impairment is associated with many chronic pain disorders. While there is an association between chronic pain and sleep disturbances, little is known about the influence of pharmacotherapy for chronic pain conditions, particularly chronic opioid therapy, on sleep. This study aimed to 1) compare the sleep quality (SQ) in patients with two different pain conditions-chronic body pain and chronic orofacial pain; 2) assess the correlation of SQ and pain intensity; and 3) evaluate the association between pharmacotherapy and SQ.

Patients and Methods

The Pittsburgh Sleep Quality Index (PSQI) was used to measure the SQ in subjects with 1) chronic body pain (n = 100) and 2) chronic orofacial pain (n = 100). The visual analogue scale was applied for pain intensity rating. All subjects were adults recruited at Massachusetts General Hospital, United States. The subjects' demographic data, pain intensity, diagnosis and concurrent use of medications were extracted from their electronic medical records (EMR). Statistical analyses were performed using T-test and Pearson correlation coefficient.

Results

Among 200 subjects (mean age 51.01 ± 15.52 years), 141 (70.5%) were females. PSQI and pain intensity were statistically significantly different between the two groups (p < 0.05 and p < 0.0001, respectively) and higher in subjects with chronic body pain. There was a positive correlation between PSQI and pain intensity (chronic orofacial pain r = 0.3535, p = 0.0004; chronic body pain: r = 0.2247, p < 0.026). PSQI was higher in chronic orofacial pain subjects utilizing opioids and benzodiazepines (PSQI = 15.25).

Conclusion

Chronic pain impairs SQ, which is noticeably worse in subjects with body pain conditions. In addition, pain intensity was correlated with poorer SQ, which in turn was linked to the concomitant use of opioid and benzodiazepine therapy in chronic orofacial pain.

A randomized, placebo-controlled, double-blinded mechanistic clinical trial using endotoxin to evaluate the relationship between insomnia, inflammation, and affective disturbance on pain in older adults: A protocol for the sleep and Healthy Aging Research for pain (SHARE-P) study

Chronic pain is prevalent in older adults. Treatment, especially with opioids, is often ineffective and poses considerable negative consequences in this population. To improve treatment, it is important to understand why older adults are at a heightened risk for developing chronic pain. Insomnia is a major modifiable risk factor for chronic pain that is ubiquitous among older adults. Insomnia can also lead to heightened systemic inflammation and affective disturbance, both of which may further exacerbate pain conditions in older adults. Endotoxin exposure can be used as an experimental model of systemic inflammation and affective disturbance. The current study aims to understand how insomnia status and endotoxin-induced changes in inflammation and affect (increased negative affect and decreased positive affect) may interact to impact pain facilitatory and inhibitory processes in older adults. Longitudinal data will also assess how pain processing, affective, and inflammatory responses to endotoxin may predict the development of pain and/or depressive symptoms. The current study is a randomized, double-blinded, placebo-controlled, mechanistic clinical trial in men and women, with and without insomnia, aged 50 years and older. Participants were randomized to either 0.8ng/kg endotoxin injection or saline placebo injection. Daily diaries were used to collect variables related to sleep, mood, and pain at two-week intervals during baseline and 3-, 6-, 9-, and 12-months post-injection. Primary outcomes during the experimental phase include conditioned pain modulation, temporal summation, and affective pain modulation ∼5.5 hours after injection. Primary outcomes for longitudinal assessments are self-reported pain intensity and depressive symptoms. The current study uses endotoxin as an experimental model for pain. In doing so, it aims to extend the current literature by: (1) including older adults, (2) investigating insomnia as a potential risk factor for chronic pain, (3) evaluating the role of endotoxin-induced affective disturbances on pain sensitivity, and (4) assessing sex differences in endotoxin-induced hyperalgesia.

Clinicaltrialsgov

NCT03256760.

Trial sponsor

NIH R01AG057750-01.

How Confinement and Back to Normal Affected the Well-Being and Thus Sleep, Headaches and Temporomandibular Disorders

The COVID-19 pandemic is having negative consequences not only for people's general health but also for the masticatory system. This article aimed to assess confinement and its new normal impact on well-being, sleep, headaches, and temporomandibular disorders (TMD). An anonymous survey was distributed to a Spanish university community. Participants completed a well-being index (WHO-5), a questionnaire related to sleep quality (the BEARS test), a headache diagnostic test (the tension type headache (TTH) and migraine diagnosis test), and the DC-TMD questionnaire. Questions were addressed in three scenarios: before confinement, during confinement, and the new normal. A total of 436 responses were collected (70% women, 30% men). A reduction in well-being and sleep quality was recorded. Respondents reported more TTH and migraines during and after confinement. Overall, confinement and return to normal did not increase TMD symptoms, and only minor effects were observed, such as more intense joint pain and a higher incidence of muscle pain in women during confinement. Reduced well-being is correlated with sleep quality loss, headaches, and TMD symptoms. This study provides evidence that pandemics and confinement might have had a negative impact on population health. Well-being was strongly affected, as were sleep quality, depression risk, TTH, and migraine frequency. In contrast, the temporomandibular joint and muscles showed more resilience and were only slightly affected.

Analgesic efficacy of sleep-promoting pharmacotherapy in patients with chronic pain: a systematic review and meta-analysis

Dysregulation of sleep heightens pain sensitivity and may contribute to pain chronification. Interventions which consolidate and lengthen sleep have the potential to improve pain control. The main objective of this systematic review was to examine the effects of sleep-promoting pharmacotherapy on pain intensity in patients with chronic pain. Multiple electronic databases were searched from inception to January 2022 to identify relevant randomized controlled trials (RCTs). Two independent reviewers screened titles, abstracts, and full-text articles; extracted data; and assessed risk of bias for each included study. The GRADE approach was used to determine the strength of evidence. The search identified 624 articles. After full-text screening, 10 RCTs (n = 574 randomized participants) involving 3 pharmacologic interventions (melatonin, zopiclone, and eszopiclone) and 7 different chronic pain populations were included. Minimum clinically significant pain reduction ≥30% was reported in 4 studies. There is low-quality evidence (downgraded due to inconsistency and imprecision) that 2 to 8 weeks treatment with a sleep-promoting medication alone or in combination with an analgesic (6 trials, n = 397) decreases pain intensity compared with placebo or the same analgesic treatment alone (SMD -0.58 [95% confidence interval -1.00, -0.17], P = 0.006). Analyses of associations between changes in sleep and pain outcomes were only provided in 2 articles, with inconsistent findings. Notably, pain-relieving effects were most consistent in melatonin trials. Only 3 studies implemented polysomnography to obtain objective sleep measures. Low-quality evidence indicates that pharmacologic sleep promotion may decrease pain intensity in chronic pain populations. More research is needed to fully understand the influence of sleep-targeting interventions on pain control.

Prevalence of self-reported symptoms of temporomandibular disorders and associated factors in the period of distance learning

OBJECTIVE

Assess the prevalence of self-reported TMD symptoms and anxiety and check the quality of sleep and life during the distance learning period in university students at the University of Brasilia (UnB).

MATERIALS AND METHODS

The participants were students from the Health Sciences College and Medicine College at UnB. Self-administered questionnaires were used to evaluate symptoms of TMD, quality of life, and sleep quality. One-way analysis of variance, followed by Bonferroni test, and Kruskal-Wallis test, followed by Dunn's test, were performed (P < 0.05). For qualitative data analysis, the chi-square test was applied (P < 0.05).

RESULTS

Total 156 students were included; prevalence of TMD, anxiety, sleep disturbance, and poor sleep quality was 73.1%, 84%, 12.8%, and 62.8%, respectively. A greater prevalence of painful TMD was observed in students with severe anxiety (P = 0.007). Students with symptoms of painful TMD, severe anxiety, and sleep disorders had statistically worse quality of life.

CONCLUSIONS

The implementation of distance learning in health courses to replace classroom teaching during the COVID-19 pandemic has impacted TMD prevalence, anxiety, quality of life, and sleep quality.

CLINICAL RELEVANCE

Psychological factors are directly associated with TMD symptoms and quality of life, TMD conditions are related to quality of life as well. COVID-19 pandemic and the distance learning in health courses are new situations that can lead to a great impact on mental health and in consequence to TMD conditions and quality of life.

Down syndrome: orofacial pain, masticatory muscle hypotonia, and sleep disorders

The aim of the present study was to investigate orofacial pain in individuals with Down syndrome (DS) and determine possible associations with masticatory muscle hypotonia (MMH), maximum mouth opening (MMO), and sleep disorders. Twenty-three individuals with DS underwent a standardized clinical examination using Axis I of the Diagnostic Criteria for Temporomandibular Disorders, for the diagnosis of pain in the masseter and temporal muscles and temporomandibular joint (TMJ). MMH was investigated using electromyography of the temporal and masseter muscles and the measurement of maximum bite force (MBF). MMO was measured using an analog caliper. Sleep disorders (obstructive sleep apnea [OSA], snoring index [SI], and sleep bruxism index [SBI]) were investigated using type II polysomnography. Statistical analysis was performed. Nonsignificant differences were found in muscle and TMJ pain between the sexes. However, myalgia and referred myofascial pain in the left masseter muscle were more frequent in males (69%) than females (40%). Electrical activity of the temporal (left: p = .002; right: p = .004) and masseter (left: p = .008) muscles was significantly lower in males than in females. MBF range was lower in males than females, indicating the highest MMH among males. OSA, SI, and SBI were identified in both sexes, but with no statistically significant differences. We concluded that myalgia and referred myofascial pain were found in some individuals with DS, especially in males. Arthralgia was found mainly in females. Temporal and masseter myalgia may have exerted an influence on the severity of MMH in males, particularly on the left side.

Subjective Sleep Complaints were Associated with Painful Temporomandibular Disorders in Adolescents: the Epidor-Adolescere Study

BACKGROUND

Sleep disturbances in adolescents has received a lot of attention in the literature and it is recognized as a serious health concern. The association between pain and sleep disturbances in adolescents has been extensively studied. However, to the best of our knowledge, there is a lack of studies investigating the association between various subjective sleep variables and painful TMD in adolescents.

OBJECTIVES

to investigate the association between painful TMD and subjective sleep variables in adolescents' non-clinical sample. We conducted a cross-sectional study. TMD was classified according to the RDC/TMD criteria. The Revised Face Scale evaluated TMD pain intensity, and pressure pain thresholds (PPTs) were assessed in trigeminal and extra-trigeminal areas. The subjective sleep variables were assessed according to the Sleep Disturbance Scale for Children and Sleep Behavior Questionnaire.

RESULTS

The final sample consisted of 690 adolescents (12.7±0.76 years), with 16.2% of them presenting painful TMD. Adolescents who frequently reported waking up more than twice per night and feeling tired when awake were more likely to present painful TMD symptoms [OR= 1.7 (95% CI: 1.04-2.90); p=0.034 and OR= 1.6 (95% CI: 1.01-2.48); p=0.046, respectively]. The intensity of TMD pain was negatively associated with sleep quality (p=0.015). Also, PPT values in the trigeminal and extra-trigeminal areas were negatively associated with total sleep time (p= 0.048 and p=0.042, respectively).

CONCLUSIONS

the present results point out the importance of considering sleep complaints associated with painful TMD in adolescents.

Insomnia with objective short sleep duration in women with temporomandibular joint disorder: quantitative sensory testing, inflammation and clinical pain profiles

OBJECTIVES/BACKGROUND

Temporomandibular joint disorder (TMD) is a disabling facial pain syndrome with a high prevalence of insomnia that primarily affects women. Insomnia with objective short sleep duration (ISSD) is an emerging phenotype linked to cardiometabolic morbidity and increased mortality. The present report examines the association of ISSD on clinical and laboratory pain and systemic inflammation in TMD.

METHODS

We collected baseline data from 128 women with TMD and insomnia as part of a clinical trial evaluating psychological interventions for sleep and pain. Participants completed self-report questionnaires, one-night polysomnography, a two-week actigraphy assessment, quantitative sensory testing (QST) to assess cold pain tolerance, pain sensitivity and central sensitization and circulating Interleukin-6 levels were measured to assess systemic inflammation.

RESULTS

24.2% (n = 31) of the sample met criteria for ISSD [polysomnography (sleep duration <6 h)]. Compared to those with insomnia and normal sleep duration, ISSD were older (40.4 vs. 34.9,p < 0.05) and a greater proportion self-identified as Black (48.4% vs 11.3%,p < 0.001). Multivariate regressions revealed that ISSD endorsed higher self-report pain severity and functional limitation of the jaw. ISSD also demonstrated increased generalized pain sensitivity, enhanced central sensitization, cold pressor tolerance and higher resting interleukin-6 levels.

CONCLUSIONS

This is the first study to characterize the ISSD phenotype in a chronic pain sample and expand the scope of its negative health outcomes to chronic pain. ISSD may be an important chronic pain phenotype associated with a more severe clinical and laboratory pain profile, and future studies should focus on implications for treatment response and disease trajectory.

CLINICAL TRIAL

ClinicalTrials.gov Identifier: NCT01794624.

Subjective Sleep Disruption and Mood Disorders are Associated with the Risk of Chronic Pain in Patients with Obstructive Sleep Apnea

OBJECTIVE

This study aimed to determine the prevalence of chronic pain and its risk factors in patients with obstructive sleep apnea (OSA).

METHODS

A total of 145 patients diagnosed with OSA were consecutively recruited from the Sleep Medicine Center in West China Hospital. All patients were divided into two groups including OSA with and without chronic pain. They were assessed the subjective sleep (Pittsburgh Sleep Quality Index, Insomnia Severity Index), objective sleep (polysomnography), mood symptoms (Hamilton Depression Rating Scale, Hamilton Anxiety Rating Scale), and pain characteristics (Short-Form McGill Pain Questionnaire). Demographic, clinical, subjective and objective sleep parameters were compared between OSA patients with and without chronic pain. Binary logistic regression models and linear regression models were used to examine the risk factors of chronic pain in OSA.

RESULTS

Fifty-five (37.9%) patients with OSA were diagnosed with chronic pain. There were more severe subjective sleep disruption and symptoms of anxiety and depression in patients with chronic pain compared to those without chronic pain. After controlling for potential confounders, poor subjective sleep quality and severe insomnia and mood disorders (all ps < 0.05), but not objective sleep fragmentation or nocturnal hypoxemia (all ps > 0.05) were associated with the increased risk of pain and pain intensity, respectively.

CONCLUSION

More than one-third of patients with OSA had chronic pain. Subjective sleep disruption and mood disorders are the risk factors of chronic pain in OSA. Our findings suggest that subjective sleep quality should be valued highly in the relationship between OSA and pain.

Acute and Chronic Temporomandibular Disorder Pain: A critical review of differentiating factors and predictors of acute to chronic pain transition

AIMS

The aims of this critical review were to: (i) assess the factors that differentiate acute from chronic temporomandibular disorders (TMD) pain; (ii) assess the risk factors associated with the transition from acute to chronic TMD pain; and (iii) summarize and appraise the studies.

METHOD

The databases used were MEDLINE, Embase, and Cochrane Database of Systematic Reviews. Eligible studies included articles comparing acute to chronic TMD pain, and cohort studies assessing the risk factors implicated in the transition from acute to chronic TMD pain.

RESULTS

Seven articles were selected: one case-control study, three cross-sectional studies, and three cohort studies. These studies found that psychological factors were more common in chronic than acute TMD pain patients; however, these factors did not increase the transition risk in the multivariable model. Myofascial and baseline pain intensity were associated with the transition from acute to chronic TMD pain at a 6-month follow-up. Due to methodological weaknesses in the available literature, more research is required to establish the risk factors implicated in the transition from acute to chronic TMD pain.

CONCLUSION

This review found some evidence that myofascial pain is associated with the transition risk from acute to chronic TMD pain at a 6-month follow-up and that pain intensity at baseline is associated with more intense TMD pain 6 months later. There is insufficient evidence to draw conclusions about the role of demographics and psychological disorders as independent risk factors.

Subjective sleep quality and temporomandibular disorders: Systematic literature review and meta-analysis

STUDY OBJECTIVES

To assess the general subjective sleep quality in individuals with and without TMD, and its distribution among the TMD diagnostic groups.

METHODS

A systematic review search was performed in Pubmed/MEDLINE, Embase, LILACS, Web of Science, SciELO, CINAHL and Cochrane Central as well as in the grey literature. Observational studies published since 1992 which used either the DC/TMD or RDC/TMD for TMD diagnosis and either the PSQI, SAQ or ESS questionnaires for sleep assessment were included. Articles selected for meta-analysis underwent quality, heterogeneity and publication bias evaluation.

RESULTS

A total of 1071 articles were found by online search, and 10 articles were added manually. For full-text reading, 138 papers were selected. Thirty-six articles were included in the final review, and 19 in the meta-analysis (PSQI only). Subjective sleep quality was shown to be associated with all RDC/TMD or DC/TMD Axis I diagnostic groups: muscle disorders, arthralgia/osteoarthritis/osteoarthrosis and disk displacements; with the highest association in the first two groups, and the lowest in the last one. A 4.45 times increased odds ratio of TMD prevalence was found for individuals who presented poor subjective sleep quality.

CONCLUSION

Subjective sleep quality should be considered in the management of TMD.

Muskuloskeletale Erkrankungen und die kraniomandibuläre Dysfunktion – eine mögliche Ursache für nichterholsamen Schlaf

Methode

Kiefer- und Kopfgelenke bilden eine kybernetische Einheit. Ziel dieser Studie ist es, mögliche Zusammenhänge zwischen schlechtem Schlaf und der kraniozervikalen (CCD) bzw. kraniomandibulären Dysfunktion (CMD) zu ermitteln.

Ergebnisse

Von den 606 untersuchten CMD-CCD-Patienten mit schlechtem Schlaf waren 65,4 % der Patienten weiblich, 34,6 % männlich; 90,3 % erfüllten zusätzlich die diagnostischen Kriterien des Fibromyalgiesyndroms der Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften. Durch die synchrone Therapie der CMD bzw. CCD und der funktionellen Wirbelsäulenstörungen konnten bei 85 % der bislang therapieresistenten CMD-CCD-Patienten mit schlechtem Schlaf eine gute Besserung der Beschwerden im Körper und bei 81,5 % eine gute Schlafbesserung erzielt werden.

Diskussion

Die CMD/CCD kann als Folge chronischer Schmerzen auftreten. Umgekehrt kann eine CMD/CCD auch eine muskuloskeletale Störung hervorrufen oder unterhalten. Chronische Schmerzen können den Schlaf stören. Bei der Diagnose und Behandlung von Schlafstörungen muss auch auf eine CMD/CCD hin untersucht und diese ggf. mitbehandelt werden.

Manual therapy associated with topical heat reduces pain and self-medication in patients with tension-type headache

ABSTRACT Tension-type headache (TTH) is a significant public health problem. The myofascial trigger points in the masticatory and cervical muscles are related to pain located in the temporomandibular joint, face, and cranium according to specific patterns. Thus, therapeutic procedures should be directed to myofascial trigger points rather than to the area of referred pain. For this purpose, the massage therapy combined with the topical heat can provide effective results due to the increase of the local microcirculation, improving tissue perfusion and promoting muscle relaxation. In this study we investigated the effects of manual therapy associated with topical heat therapy in TTH pain. This is a single-arm study composed of 13 participants with TTH (females), which were submitted to a three-month research protocol. In the first month , they filled out a pain diary and then they were evaluated. In the following month, the treatment protocol was applied (8 sessions of 45 minutes, twice a week, involving massage for skin desensitization, myofascial trigger point deactivation and stretching (friction massage) on masticatory and trapezius muscles after the topical heat). Then, in the third month (follow-up period), the participants were instructed to fill out the pain diary once again. We observed a significant decrease in pain intensity in TTH episodes, and medication intake after treatment and it keeps decreasing in follow-up. We conclude that the combination of manual therapy protocol and topical heat reduced pain and episodes related to TTH, and self-medication use in our sample.

Preliminary evidence for conserved transcriptional response to adversity in adults with temporomandibular disorder

Temporomandibular disorder (TMD) is one of the most common orofacial pain conditions. Alteration in immune functioning is one promising biological mechanism underlying pain in TMD. However, there is a gap in the understanding of molecular bases contributing to altered immune functioning in these patients.

OBJECTIVES

In the current study, we investigated whether individuals with TMD would exhibit differential activity of 3 specific transcription factors involved in inflammatory (nuclear factor-kappa B, NF-kB), antiviral (interferon-regulatory factors, IRF), and sympathetic (cAMP response element-binding protein, CREB) processes using a promoter-based bioinformatics analysis, which is characterized as the "Conserved Transcriptional Response to Adversity."

METHODS

Adults with TMD (n = 19) and without (n = 17) underwent a standardized clinical examination for TMD. A blood sample was collected for genome-wide transcriptional RNA profiling. Bioinformatic analyses tested for differential prevalence of proinflammatory and antiviral transcription factor activity in core promoter sequences from all genes showing >1.2-fold differential expression in TMD vs controls.

RESULTS

Promoter-based bioinformatic analyses of genome-wide transcriptome profiles confirmed upregulation of genes bearing response elements for proinflammatory transcription factor (NF-kB, P = 0.002) and downregulation of genes with response elements for IRF (P = 0.037) in patients with TMD relative to controls. Results also indicated upregulated activity of CREB in patients with TMD (P = 0.08), consistent with increased activity of the sympathetic nervous system.

CONCLUSION

These results provide initial support that the regulation of immune pathways is altered in individuals with TMD. A shift of transcriptional resources to a proinflammatory state may be driven by psychosocial stress and contributes to symptoms associated with TMD.

The role of sleep dysfunction in temporomandibular onset and progression: A systematic review and meta-analyses

BACKGROUND

Painful temporomandibular (TM) disorders result in 4.3 billion dollars spent annually in the United States. The complex interplay of physiological processes in persistent pain and dysfunctional sleep has been established. Recently, dysfunctional sleep has been identified as a potential pathway to the onset of painful TM disorder.

OBJECTIVES

The aims were to (1) identify self-report outcome measures (SROMs) of sleep quality that are clinimetrically sound in patients with painful TM disorders and (2) determine whether sleep dysfunction has any diagnostic or prognostic value for this population.

METHODS

A systematic search following PRISMA guidelines was run in six databases: CINAHL, Dental, PsychALL, PubMed, Scopus and Web of Science. Any study involving minors was excluded. Risks of biases were examined in all studies. Diagnostic pooled findings were reported.

RESULTS

Of the identified articles (n = 681), 18 were included in this systematic review (n = 1 clinimetric studies, n = 11 diagnostic studies, n = 6 prognostic studies). Nine different assessment tools were used; only the Pittsburg Sleep Quality Index (PSQI) has been validated in patients with painful TM disorders. Overall, sleep dysfunction was diagnostic for painful TM disorders. The pooled relative risk of sleep dysfunction was 1.71 (95% CI 1.30. 2.26). When PSQI scores were greater than 5/21, the unadjusted hazard ratio for development of painful TM disorders was reported to be 2.1.

CONCLUSION

At present, the only SROM that has diagnostic and prognostic value in evaluating and managing patients with painful TM disorders is the PSQI.

Orofacial pain education in dentistry: A path to improving patient care and reducing the population burden of chronic pain

Dentists stand in an optimal position to prevent and manage patients suffering from chronic orofacial pain (OFP) disorders, such as temporomandibular disorders, burning mouth syndrome, trigeminal neuralgia, persistent idiopathic dentoalveolar pain, among others. However, there are consistent reports highlighting a lack of knowledge and confidence in diagnosing and treating OFP among dental students, recent graduates, and trained dentists, which leads to misdiagnosis, unnecessary costs, delay in appropriate care and possible harm to patients. Education in OFP is necessary to improve the quality of general dental care and reduce individual and societal burden of chronic pain through prevention and improved quality of life for OFP patients. Our aims are to emphasize the goals of OFP education, to identify barriers for its implementation, and to suggest possible avenues to improve OFP education in general, postgraduate, and continuing dental education levels, including proposed minimum OFP competencies for all dentists. Moreover, patient perspectives are also incorporated, including a testimony from a person with OFP. General dentists, OFP experts, educators, researchers, patients, and policy makers need to combine efforts in order to successfully address the urgent need for quality OFP education.

Sleep and Pain: A Systematic Review of Studies of Mediation

Supplemental Digital Content is available in the text.

Objectives:

A relationship between sleep and pain is well established. A better understanding of the mechanisms that link sleep and pain intensity is urgently needed to optimize pain management interventions. The objective of this systematic review was to identify, synthesize, and critically appraise studies that have investigated putative mediators on the path between sleep and pain intensity.

Methods:

A systematic search of 5 electronic bibliographic databases (EMBASE, MEDLINE, CINAHL, PsycINFO, and the Cochrane Central Register of Controlled Trials) was conducted. Eligible studies had to apply a formal test of mediation to variables on the path between a sleep variable and pain intensity or vice versa. All searches, data extraction and quality assessment were conducted by at least 2 independent reviewers.

Results:

The search yielded 2839 unique articles, 9 of which were eligible. Of 13 mediation analyses, 11 investigated pathways from a sleep variable to pain intensity. Putative mediators included affect/mood, depression and/or anxiety, attention to pain, pain helplessness, stress, fatigue, and physical activity. Two analyses investigated pathways from pain intensity to a sleep variable, examining the potentially mediating role of depressive symptoms and mood. Although evidence supported a mediating role for psychological and physiological aspects of emotional experiences and attentional processes, methodological limitations were common, including use of cross-sectional data and minimal adjustment for potential confounders.

Discussion:

A growing body of research is applying mediation analysis to elucidate mechanistic pathways between sleep and pain intensity. Currently sparse evidence would be illuminated by more intensively collected longitudinal data and improvements in analysis.

The face of Dental Sleep Medicine in the 21st century

It becomes increasingly clear that some sleep disorders have important diagnostic and/or management links to the dental domain, hence the emergence of the discipline ‘Dental Sleep Medicine’. In this review, the following topics are discussed: 1. the reciprocal associations between oro‐facial pain and sleep; 2. the associations between sleep bruxism and other sleep‐related disorders; 3. the role of the dentist in the assessment and management of sleep bruxism; and 4. the dental management of obstructive sleep apnoea. From these topics' descriptions, it becomes clear that the role of the dentist in the recognition and management of sleep‐related oro‐facial pain, sleep bruxism and obstructive sleep apnoea is large and important. Since many dental sleep disorders can have severe consequences for the individual's general health and well‐being, it is imperative that dentists are not only willing to take on that role, but are also able to do so. This requires more attention for Dental Sleep Medicine in the dental curricula worldwide, as well as better postgraduate training of dentists who are interested in specialising in this intriguing domain. This review contributes to increasing the dental researcher's, teacher's and care professional's insight into the discipline ‘Dental Sleep Medicine’ as it has taken shape in the 21st century, to the benefit of all patients suffering from dental sleep disorders.

Sex differences in measures of central sensitization and pain sensitivity to experimental sleep disruption: implications for sex differences in chronic pain

Study Objectives

Females demonstrate heightened central sensitization (CS), a risk factor for chronic pain characterized by enhanced responsivity of central nervous system nociceptors to normal or subthreshold input. Sleep disruption increases pain sensitivity, but sex has rarely been evaluated as a moderator and few experiments have measured CS. We evaluated whether two nights of sleep disruption alter CS measures of secondary hyperalgesia and mechanical temporal summation in a sex-dependent manner. We also evaluated differences in measures of pain sensitivity.

Methods

Seventy-nine healthy adults (female n = 46) participated in a randomized crossover experiment comparing two consecutive nights of eight pseudorandomly distributed forced awakenings (FA [-200 min sleep time]) against two nights of undisturbed sleep (US). We conducted sensory testing the mornings following Night 2; the heat-capsaicin pain model was used to induce secondary hyperalgesia.

Results

FA reduced total sleep time (REM and NREM Stage 3) more profoundly in males. We observed divergent, sex-dependent effects of FA on secondary hyperalgesia and temporal summation. FA significantly increased secondary hyperalgesia in males and significantly increased temporal summation in females. Sex differences were not attributable to differential sleep loss in males. FA also significantly reduced heat-pain threshold and cold pressor pain tolerance, independently of sex.

Conclusions

Sleep disruption enhances different pain facilitatory measures of CS in males and females suggesting that sleep disturbance may increase risk for chronic pain in males and females via distinct pathways. Findings have implications for understanding sex differences in chronic pain and investigating sleep in chronic pain prevention efforts.

Associations of Sleep Disturbance, Atopy, and Other Health Measures with Chronic Overlapping Pain Conditions

AIMS

To quantify the contributions of atopic disorders, sleep disturbance, and other health conditions to five common pain conditions.

METHODS

This cross-sectional analysis used data from 655 participants in the OPPERA study. The authors investigated the individual and collective associations of five chronic overlapping pain conditions (COPCs) with medically diagnosed atopic disorders and self-reported sleep disturbance, fatigue, and symptoms of obstructive sleep apnea. Atopic disorders were allergies, allergic rhinitis, atopic dermatitis, allergic asthma, urticaria, allergic conjunctivitis, and food allergy. Logistic regression models estimated odds ratios as measures of association with temporomandibular disorders, headache, irritable bowel syndrome, low back pain, and fibromyalgia. Measures of sleep and atopy disorders were standardized to z scores to determine the relative strength of their associations with each COPC. Sociodemographic characteristics and body mass index were covariates. Random forest regression analyzed all variables simultaneously, computing importance metrics to determine which variables best differentiated pain cases from controls.

RESULTS

Fatigue and sleep disturbance were strongly associated with each COPC and with the total number of COPCs. An increase of one standard deviation in fatigue or sleep disturbance score was associated with approximately two-fold greater odds of having a COPC. In random forest models, atopic disorders contributed more than other health measures to differentiating between cases and controls of headache, whereas other COPCs were best differentiated by measures of fatigue or sleep.

CONCLUSION

Atopic disorders, previously recognized as predictors of poor sleep, are associated with COPCs after accounting for sleep problems.

Evaluation of Association between the Severity of Temporomandibular Disorders and Quality of Sleep in a Selected Iranian Population

OBJECTIVES

Temporomandibular disorder (TMD), as a prevalent condition, has been reported to be related to changes in sleep quality. This study aims to assess the association between TMD severities and sleep quality in a selected Iranian population by the application of the Helkimo index and the Pittsburgh Sleep Quality Index (PSQI) questionnaire.

MATERIALS AND METHODS

This study comprised 50 non-TMD subjects and 150 TMD patients, which were equally selected from each TMD severity category. The study was conducted at the School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. The patients were first examined and categorized into four TMD severity groups according to the Helkimo index: Non-TMD, mild, moderate, and severe. Then, the patients completed the PSQI questionnaire, which was a standard version translated into Persian and adjusted for Iranian patients.

RESULTS

Comparison of mean PSQI scores of the four groups revealed a significant difference (P<0.001). Pairwise comparisons showed that the severe, moderate, and mild TMD groups and the control received the highest to the lowest PSQI scores (12.26±2.35, 8.20±1.92, 6.88±1.89, and 5.28±1.32, respectively). Similarly, regression analysis indicated that by controlling the effect of demographic variables, the mean PSQI significantly increased as TMD severity increased.

CONCLUSION

According to the results, all three categories of mild, moderate, and severe TMD patients showed poor quality of sleep in comparison with non-TMD controls. The higher the severity of the disease, the lower the sleep quality.

Association between sleeping time and temporomandibular disorders in a sample of the South Korean population

Objective: This study investigated the relationship between sleeping time and temporomandibular disorders (TMDs).Methods: This study used data from the Fifth Korea National Health and Nutrition Examination Survey from 2010 to 2011. The final sample size consisted of 11,782 adults aged ≥19 years. Logistic regression analysis was performed to assess the relationship between sleeping time and TMD.Results: The adjusted odds ratios of the TMD group were 1.421 (1.067, 1.892) (Model 1), 1.388 (1.028, 1.873) (Model 2), and 1.360 (1.012, 1.826) (Model 3) for subjects with sleeping time ≤5 hours (p < 0.05) and 1.317 (0.992, 1.748) (Model 1), 1.358 (1.01, 1.827) (Model 2), and 1.352 (0.977, 1.872) (Model 3) for subjects with sleeping time ≥9 hours (p < 0.05).Conclusion: Sleeping time ≤5 hours and ≥9 hours were associated with an increased rate of TMD.

Long-term changes in biopsychosocial characteristics related to temporomandibular disorder: findings from the OPPERA study

Painful temporomandibular disorders (TMDs) are both consequence and cause of change in multiple clinical, psychosocial, and biological factors. Although longitudinal studies have identified antecedent biopsychosocial factors that increase risk of the TMD onset and persistence, little is known about long-term change in those factors after TMD develops or remits. During a 7.6-year median follow-up period, we measured change in psychosocial characteristics, pain sensitivity, cardiovascular indicators of autonomic function, and clinical jaw function among 189 participants whose baseline chronic TMD status either persisted or remitted and 505 initially TMD-free participants, 83 of whom developed TMD. Among initially TMD-free participants who developed TMD, symptoms and pain sensitivity increased, whereas psychological function worsened. By contrast, participants with chronic TMD at baseline tended to show improved TMD symptoms, improved jaw function, reduced somatic symptoms, and increased positive affect. In general, clinical and psychosocial variables more frequently changed in parallel with TMD status compared with pain sensitivity and autonomic measures. These findings demonstrate a complex pattern of considerable changes in biopsychosocial function associated with changes in TMD status. In particular, several biopsychosocial parameters improved among participants with chronic TMD despite pain persisting for years, suggesting considerable potential for ongoing coping and adaptation in response to persistent pain.

Sleep, Sleep Disorders, and Circadian Health following Mild Traumatic Brain Injury in Adults: Review and Research Agenda

A rapidly expanding scientific literature supports the frequent co-occurrence of sleep and circadian disturbances following mild traumatic brain injury (mTBI). Although many questions remain unanswered, the preponderance of evidence suggests that sleep and circadian disorders can result from mTBI. Among those with mTBI, sleep disturbances and clinical sleep and circadian disorders contribute to the morbidity and long-term sequelae across domains of functional outcomes and quality of life. Specifically, along with deterioration of neurocognitive performance, insufficient and disturbed sleep can precede, exacerbate, or perpetuate many of the other common sequelae of mTBI, including depression, post-traumatic stress disorder, and chronic pain. Further, sleep and mTBI share neurophysiologic and neuroanatomic mechanisms that likely bear directly on success of rehabilitation following mTBI. For these reasons, focus on disturbed sleep as a modifiable treatment target has high likelihood of improving outcomes in mTBI. Here, we review relevant literature and present a research agenda to 1) advance understanding of the reciprocal relationships between sleep and circadian factors and mTBI sequelae and 2) advance rapidly the development of sleep-related treatments in this population.

A high prevalence of TMD is related to somatic awareness and pain intensity among healthy dental students

OBJECTIVE

Dental students have been identified as a group with high risks of developing both temporomandibular disorders (TMD) and psychosocial conditions. Our primary aim was to evaluate the cross-sectional prevalence of TMD diagnoses, as defined in the Diagnostic Criteria (DC)/TMD, among dental students. The secondary aim was to evaluate the prevalence and association of behavioural and psychosocial factors in relation to DC/TMD diagnoses.

MATERIALS AND METHODS

The study was conducted among undergraduate dental students during the second semester of their third year at the Department of Odontology, Medical Faculty, Umeå University, Sweden. Three consecutive cohorts were recruited during August in 2013, 2014, 2015. In total, 54 students were included and examined according the DC/TMD procedure.

RESULTS AND CONCLUSIONS

The prevalence of any DC/TMD diagnosis was 30%. The most prevalent TMD diagnosis was myalgia. Individuals with a TMD-pain diagnosis (i.e. myalgia or arthralgia) reported significantly higher pain intensity levels according to the Graded Chronic Pain Scale (GCPS) as compared to individuals without TMD-pain (Fisher's exact test p < .001, two-sided). In addition, individuals with any TMD scored significantly higher jaw functional limitations according to the Jaw Functional Limitation Scale 20 (JFLS-20, p < .001) and oral parafunctions according to the Oral Behavior Checklist (OBC, p = .005) as compared to individuals without TMD. The psychosocial factors evaluated did not differ between individual with or without a TMD diagnosis. The majority of the dental students reported symptoms that are already identified as risk factors for developing TMD and pain conditions. However, longitudinal data are needed to evaluate how this evolves over time.

Exploring the Role of Negative Cognitions in the Relationship Between Ethnicity, Sleep, and Pain in Women With Temporomandibular Joint Disorder

Negative cognitions are central to the perpetuation of chronic pain and sleep disturbances. Patients with temporomandibular joint disorder (TMJD), a chronic pain condition characterized by pain and limitation in the jaw area, have a high comorbidity of sleep disturbances that possibly exacerbate their condition. Ethnic group differences are documented in pain, sleep, and coping, yet the mechanisms driving these differences are still unclear, especially in clinical pain populations. We recruited 156 women (79% white, 21% African American) diagnosed with TMJD as part of a randomized, controlled trial evaluating the effectiveness of interventions targeting sleep and pain catastrophizing on pain in TMJD. Analysis of baseline data demonstrated that, relative to white participants, African Americans exhibited higher levels of clinical pain, insomnia severity, and pain catastrophizing, yet there was no ethnic group difference in negative sleep-related cognitions. Mediation models revealed pain catastrophizing, but not sleep-related cognitions or insomnia severity, to be a significant single mediator of the relationship between ethnicity and clinical pain. Only the helplessness component of catastrophizing together with insomnia severity sequentially mediated the ethnicity-pain relationship. These findings identify pain catastrophizing as a potentially important link between ethnicity and clinical pain and suggest that interventions targeting pain-related helplessness could improve both sleep and pain, especially for African American patients. Perspective:Pain-related helplessness and insomnia severity contribute to ethnic differences found in clinical pain among woman with TMJD. Findings can potentially inform interventions that target insomnia and catastrophizing to assist in reducing ethnic disparities in clinical pain.

Depressive symptoms account for differences between self-reported versus polysomnographic assessment of sleep quality in women with myofascial TMD

Patients with temporomandibular disorder (TMD) report poor sleep quality on the Pittsburgh Sleep Quality Index (PSQI). However, polysomnographic (PSG) studies show meagre evidence of sleep disturbance on standard physiological measures. The present aim was to analyse self-reported sleep quality in TMD as a function of myofascial pain, PSG parameters and depressive symptomatology. PSQI scores from 124 women with myofascial TMD and 46 matched controls were hierarchically regressed onto TMD presence, ratings of pain intensity and pain-related disability, in-laboratory PSG variables and depressive symptoms (Symptoms Checklist-90). Relative to controls, TMD cases had higher PSQI scores, representing poorer subjective sleep and more depressive symptoms (both P < 0·001). Higher PSQI scores were strongly predicted by more depressive symptoms (P < 0·001, R² = 26%). Of 19 PSG variables, two had modest contributions to higher PSQI scores: longer rapid eye movement latency in TMD cases (P = 0·01, R² = 3%) and more awakenings in all participants (P = 0·03, R² = 2%). After accounting for these factors, TMD presence and pain ratings were not significantly related to PSQI scores. These results show that reported poor sleep quality in TMD is better explained by depressive symptoms than by PSG-assessed sleep disturbances or myofascial pain. As TMD cases lacked typical PSG features of clinical depression, the results suggest a negative cognitive bias in TMD and caution against interpreting self-report sleep measures as accurate indicators of PSG sleep disturbance. Future investigations should take account of depressive symptomatology when interpreting reports of poor sleep.

Causal Mediation in the Development of Painful Temporomandibular Disorder

We explored causal mediation of sleep quality and perceived stress in development of painful temporomandibular disorder (TMD). Sleep quality and perceived stress were assessed at baseline and quarterly intervals thereafter in 2,737 initially TMD-free adults in the Orofacial Pain Prospective Evaluation and Risk Assessment study (OPPERA) prospective cohort study. During follow-up, incident TMD cases were classified using research diagnostic criteria. Mediation analysis was conducted using a weighted Cox proportional hazards regression model that estimated hazard ratios (HRs) and 95% confidence limits (CL) of first-onset TMD. Models determined whether: 1) poor sleep quality during follow-up mediated the effect of baseline perceived stress on first-onset TMD, and 2) perceived stress during follow-up mediated the effect of baseline poor sleep quality on first-onset TMD. In both analyses, the total effect was decomposed into natural direct and indirect effects. Poor baseline sleep quality led to heightened perceived stress that then contributed to TMD development. When the total effect of poor sleep quality (HR = 2.10, CL = 1.76, 2.50) was decomposed, 34% of its effect was mediated by perceived stress (indirect effect HR = 1.29, CL = 1.06, 1.58). The effect of perceived stress on first-onset TMD was not mediated by sleep quality. Improving sleep may avert escalation of stress, limiting effects of both factors on TMD development.

PERSPECTIVE

Causal mediation analysis highlights mechanisms by which poor sleep quality promotes development of TMD. First, poor sleep quality exerts a direct effect on pain. Second, it triggers a heightened perception of stress, which acts as an intermediate factor in the causal pathway between poor sleep quality and first-onset TMD pain.

Painful Temporomandibular Disorder: Decade of Discovery from OPPERA Studies

In 2006, the OPPERA project (Orofacial Pain: Prospective Evaluation and Risk Assessment) set out to identify risk factors for development of painful temporomandibular disorder (TMD). A decade later, this review summarizes its key findings. At 4 US study sites, OPPERA recruited and examined 3,258 community-based TMD-free adults assessing genetic and phenotypic measures of biological, psychosocial, clinical, and health status characteristics. During follow-up, 4% of participants per annum developed clinically verified TMD, although that was a "symptom iceberg" when compared with the 19% annual rate of facial pain symptoms. The most influential predictors of clinical TMD were simple checklists of comorbid health conditions and nonpainful orofacial symptoms. Self-reports of jaw parafunction were markedly stronger predictors than corresponding examiner assessments. The strongest psychosocial predictor was frequency of somatic symptoms, although not somatic reactivity. Pressure pain thresholds measured at cranial sites only weakly predicted incident TMD yet were strongly associated with chronic TMD, cross-sectionally, in OPPERA's separate case-control study. The puzzle was resolved in OPPERA's nested case-control study where repeated measures of pressure pain thresholds revealed fluctuation that coincided with TMD's onset, persistence, and recovery but did not predict its incidence. The nested case-control study likewise furnished novel evidence that deteriorating sleep quality predicted TMD incidence. Three hundred genes were investigated, implicating 6 single-nucleotide polymorphisms (SNPs) as risk factors for chronic TMD, while another 6 SNPs were associated with intermediate phenotypes for TMD. One study identified a serotonergic pathway in which multiple SNPs influenced risk of chronic TMD. Two other studies investigating gene-environment interactions found that effects of stress on pain were modified by variation in the gene encoding catechol O-methyltransferase. Lessons learned from OPPERA have verified some implicated risk factors for TMD and refuted others, redirecting our thinking. Now it is time to apply those lessons to studies investigating treatment and prevention of TMD.