Potential psychosocial risk factors for chronic TMD: descriptive data and empirically identified domains from the OPPERA case-control study

Patients with Concomitant Chronic Neck Pain and Myofascial Pain in Masticatory Muscles Have More Widespread Pain and Distal Hyperalgesia than Patients with Only Chronic Neck Pain

Objective

Insufficient evidence exists to compare widespread pain (WP), pain sensibility, and psychological factors that occur in patients presenting with chronic neck pain (CNP) or a combination of temporomandibular disorder (TMD) and other complaints. The present study compared the pain sensibility and psychological factors of subjects with CNP with those with TMD + CNP.

Design

Cross-sectional study.

Setting

Local community.

Subjects

A nonprobabilistic convenience sample of 86 persons with CNP or TMD was recruited into three groups: CNP, TMD with myofascial pain in masticatory muscles with cocomitant CNP (TMD + CNP), and asymptomatic control groups consisted of 27, 29, and 30 participants, respectively.

Methods

Participants underwent a clinical examination to evaluate WP with computerized assessment based on the pain drawing, pressure pain thresholds (PPT), and psychological factors, which were evaluated using the pain catastrophizing scale (PCS) and the state-trait anxiety inventory (STAI).

Results

Statistically significant differences were observed between participants with CNP and TMD + CNP for WP (t = -2.80, P  < 0.01, d = -1.06). Post hoc analyses only revealed significant differences between TMD + CNP participants and asymptomatic controls for PPT at extratrigeminal areas. Pearson correlation analyses showed a moderate positive association between symptomatic groups within the WP and STAI ( P  < 0.05) and a moderate negative association between PCS and PPT ( P  < 0.05) at the right tibialis muscle.

Conclusion

TMD + CNP participants had more areas of pain and also showed widespread pain hyperalgesia. Both groups of participants had psychological factors positively associated with STAI and WP; further, PCS and the PPT at the extratrigeminal region were negatively associated with each other in both groups, except for the left tibialis in the TMD + CNP group.

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.

Identification of relevant subtypes via preweighted sparse clustering

Cluster analysis methods are used to identify homogeneous subgroups in a data set. In biomedical applications, one frequently applies cluster analysis in order to identify biologically interesting subgroups. In particular, one may wish to identify subgroups that are associated with a particular outcome of interest. Conventional clustering methods generally do not identify such subgroups, particularly when there are a large number of high-variance features in the data set. Conventional methods may identify clusters associated with these high-variance features when one wishes to obtain secondary clusters that are more interesting biologically or more strongly associated with a particular outcome of interest. A modification of sparse clustering can be used to identify such secondary clusters or clusters associated with an outcome of interest. This method correctly identifies such clusters of interest in several simulation scenarios. The method is also applied to a large prospective cohort study of temporomandibular disorders and a leukemia microarray data set.

Association Between Severity of Temporomandibular Disorders and the Frequency of Headache Attacks in Women With Migraine: A Cross-Sectional Study

OBJECTIVE

The aim of this study was to investigate the magnitude of association of the severity of temporomandibular disorders (TMDs) in women with episodic and chronic migraine.

METHODS

Thirty-one women with episodic migraine (mean age: 33 years), 21 with chronic migraine (mean age: 35 years) and 32 healthy controls (mean age: 31 years) were included. The Fonseca Anamnestic Index was applied to assess severity of TMDs. TMD severity was considered as follows: no TMD (0-19 points), mild TMD (20-49 points), moderate TMD (50-69 points), and severe TMD (70-100 points). To compare the proportion of TMD severity among groups, a χ² test was performed. Prevalence ratio (PR) was calculated to determine the association of TMD severity and both migraine groups using the control group as the reference.

RESULTS

Women with chronic and episodic migraine were more likely to exhibit TMD signs and symptoms of any severity than healthy controls (χ² = 30.26; P < .001). TMD prevalence was 54% for healthy controls, 78% for episodic migraine, and 100% for chronic migraine. Women with chronic migraine exhibited greater risk of more severe manifestations of TMD than healthy controls (PR: 3.31; P = .008). This association was not identified for episodic migraine (PR: 2.18; P = .101).

CONCLUSION

The presence of TMD signs and symptoms was associated with migraine independently of the frequency; however, the magnitude of the association of more severe TMD was significantly greater in chronic, but not episodic, migraine.

Is there an association between fear avoidance beliefs, and pain and disability in patients with orofacial pain?

Numerous psychosocial factors have been shown to contribute to the development and perpetuation of orofacial pain. One well-recognized model for explaining the link between psychosocial factors and chronic pain is the fear avoidance model. To date, this proposed link has not been studied in subjects with orofacial pain. During the initial evaluation of subjects with orofacial pain, we collected data on fear avoidance beliefs using the Fear Avoidance Beliefs Questionnaire, and disability and pain. At between 6 and 8 weeks follow-up, we re-collected these data, as well as data addressing subjects' perceived change in their condition. Data were analyzed using correlation coefficients and linear regression. Fear avoidance beliefs at intake were inversely correlated with intake disability, There were no significant associations between fear avoidance beliefs at initial evaluation or in changes in fear avoidance beliefs during the 6-8 weeks follow-up period; and changes in disability, pain or perceived change in condition at 6-8 weeks follow-up. Of note, fear avoidance beliefs increased over the follow-up period, despite improvements in all outcome measures. There was insufficient evidence to suggest that high levels of fear avoidance beliefs at initial evaluation are associated with higher levels of disability or pain at intake, or with change in disability, pain or perceived change in condition at 6-8 weeks follow-up. Similarly, there was insufficient evidence to suggest that changes in fear avoidance beliefs during treatment are associated with any of these outcome measures.

Identification of clusters of individuals relevant to temporomandibular disorders and other chronic pain conditions: the OPPERA study

The classification of most chronic pain disorders gives emphasis to anatomical location of the pain to distinguish one disorder from the other (eg, back pain vs temporomandibular disorder [TMD]) or to define subtypes (eg, TMD myalgia vs arthralgia). However, anatomical criteria overlook etiology, potentially hampering treatment decisions. This study identified clusters of individuals using a comprehensive array of biopsychosocial measures. Data were collected from a case-control study of 1031 chronic TMD cases and 3247 TMD-free controls. Three subgroups were identified using supervised cluster analysis (referred to as the adaptive, pain-sensitive, and global symptoms clusters). Compared with the adaptive cluster, participants in the pain-sensitive cluster showed heightened sensitivity to experimental pain, and participants in the global symptoms cluster showed both greater pain sensitivity and greater psychological distress. Cluster membership was strongly associated with chronic TMD: 91.5% of TMD cases belonged to the pain-sensitive and global symptoms clusters, whereas 41.2% of controls belonged to the adaptive cluster. Temporomandibular disorder cases in the pain-sensitive and global symptoms clusters also showed greater pain intensity, jaw functional limitation, and more comorbid pain conditions. Similar results were obtained when the same methodology was applied to a smaller case-control study consisting of 199 chronic TMD cases and 201 TMD-free controls. During a median 3-year follow-up period of TMD-free individuals, participants in the global symptoms cluster had greater risk of developing first-onset TMD (hazard ratio = 2.8) compared with participants in the other 2 clusters. Cross-cohort predictive modeling was used to demonstrate the reliability of the clusters.

Chronic Orofacial Pain: Burning Mouth Syndrome and Other Neuropathic Disorders

Chronic orofacial pain is a symptom associated with a wide range of neuropathic, neurovascular, idiopathic, and myofascial conditions that affect a significant proportion of the population. While the collective impact of the subset of the orofacial pain disorders involving neurogenic and idiopathic mechanisms is substantial, some of these are relatively uncommon. Hence, patients with these disorders can be vulnerable to misdiagnosis, sometimes for years, increasing the symptom burden and delaying effective treatment. This manuscript first reviews the decision tree to be followed in diagnosing any neuropathic pain condition, as well as the levels of evidence needed to make a diagnosis with each of several levels of confidence: definite, probable, or possible. It then examines the clinical literature related to the idiopathic and neurogenic conditions that can occasion chronic orofacial pain, including burning mouth syndrome, trigeminal neuralgia, glossopharyngeal neuralgia, post-herpetic neuralgia, and atypical odontalgia. Temporomandibular disorders also are examined as are other headache conditions, even though they are not neurologic conditions, because they are common and can mimic symptoms of the latter disorders. For each of these conditions, the paper reviews literature regarding incidence and prevalence, physiologic and other contributing factors, diagnostic signs and symptoms, and empirical evidence regarding treatments. Finally, in order to improve the quality and accuracy of clinical diagnosis, as well as the efficiency with which effective treatment is initiated and delivered, criteria are offered that can be instrumental in making a differential diagnosis.

Occlusal stabilization splint for patients with temporomandibular disorders: Meta-analysis of short and long term effects

Background

Psychological discomfort, physical disability and functional limitations of the orofacial system have a major impact on everyday life of patients with temporomandibular disorders (TMDs). In this study we sought to determine short and long term effects of stabilization splint (SS) in treatment of TMDs, and to identify factors influencing its efficacy.

Methods

MEDLINE, Web of Science and EMBASE were searched for randomized controlled trials (RCTs) comparing SS to: non-occluding splint, occlusal oral appliances, physiotherapy, behavioral therapy, counseling and no treatment. Random effects method was used to summarize outcomes. The effect estimates were expressed as odds ratio (OR) or standardized mean difference (SMD) with 95% confidence interval. Subgroup analyses were carried out according to the use of Research Diagnostic Criteria (RDC/TMD) and TMDs origin. Strength of evidence was assessed by GRADE. Meta-regression was applied.

Results

Thirty three eligible RCTs were included in meta-analysis. In short term, SS presented positive overall effect on pain reduction (OR 2.08; p = 0.01) and pain intensity (SMD -0.33; p = 0.02). Subgroup analyses confirmed SS effect in studies used RDC/TMD and revealed its effect in patients with TMDs of muscular origin. Important decrease of muscle tenderness (OR 1.97; p = 0.03) and improvement of mouth opening (SMD -0.30; p = 0.04) were found. SS in comparison to oral appliances showed no difference (OR 0.74; p = 0.24). Meta-regression identified continuous use of SS during the day as a factor influencing efficacy (p = 0.01). Long term results showed no difference in observed outcomes between groups. Low quality of evidence was found for primary outcomes.

Conclusion

SS presented short term benefit for patients with TMDs. In long term follow up, the effect is equalized with other therapeutic modalities. Further studies based on appropriate use of standardized criteria for patient recruitment and outcomes under assessment are needed to better define SS effect persistence in long term.

Risk Factors for Facial Pain: Data from the Osteoarthritis Initiative Study

AIMS

Temporomandibular disorder (TMD) is believed to be co-morbid with rheumatologic conditions such as Osteoarthritis (OA). We determine 30-day prevalence and cumulative incidence, and risk factors for facial pain in a cohort of subjects who either had or were at risk of developing symptomatic radiographic knee osteoarthritis (SRKOA).

METHODS

Poisson regression models examined whether age, sex, race, Center for Epidemiologic Studies-Depression Scale (CES-D) score, number of painful joints, and presence of SRKOA were risk factors for facial pain in 4,423 subjects at baseline and in 3,472 subjects at 24 and/or 48 months follow-up.

RESULTS

At baseline, 30-day period prevalence of facial pain was 9.25%; and 30-day cumulative incidence at 24-months and at 48-months was 5.9% and 4.9%, respectively. Factors associated with prevalence and incidence of facial pain were: younger age, female sex, (CES-D) score, and a larger number of painful joints. For each increase in age of one year, the incidence of facial pain decreased by 1%. Women had a 96% higher incidence than men, and each unit increase of (CES-D) score was associated with a 2% increase in the incidence of facial pain. For every additional painful joint, there was a 21% increase in the incidence of facial pain. Subjects with SRKOA had a 33% increase in the incidence of facial pain compared to those with risk factors for SRKOA.

CONCLUSION

OA and TMD share several risk factors. The risk factors identified in cross-sectional analysis of prevalence are similar to those identified in longitudinal analysis on incidence.

Design, construction, and technical implementation of a web-based interdisciplinary symptom evaluation (WISE) - a heuristic proposal for orofacial pain and temporomandibular disorders

BACKGROUND

Medical symptoms independent of body location burden individuals to varying degrees and may require care by more than one expert. Various paper and computer-based tools exist that aim to comprehensively capture data for optimal clinical management and research.

METHODS

A web-based interdisciplinary symptom evaluation (WISE) was newly designed, constructed, and technically implemented. For worldwide applicability and to avoid copyright infringements, open source software tools and free validated questionnaires available in multiple languages were used. Highly secure data storage limits access strictly to those who use the tool for collecting, storing, and evaluating their data. Concept and implementation is illustrated by a WISE sample tailored for the requirements of a single center in Switzerland providing interdisciplinary care to orofacial pain and temporomandibular disorder patients.

RESULTS

By combining a symptom- burden checklist with in-depth questionnaires serving as case-finding instruments, an algorithm was developed that assists in clarifying case complexity and need for targeted expert evaluation. This novel modular approach provides a personalized, response-tailored instrument for the time- and cost-effective collection of symptom-burden focused quantitative data. The tool includes body drawing options and instructional videos. It is applicable for biopsychosocial evaluation in a variety of clinical settings and offers direct feedback by a case report summary.

CONCLUSIONS

In clinical practice, the new instrument assists in clarifying case complexity and referral need, based on symptom burden and response -tailored case finding. It provides single-case summary reports from a biopsychosocial perspective and includes graphical symptom maps. Secure, centrally stored data collection of anonymous data is possible. The tool enables personalized medicine, facilitates interprofessional education and collaboration, and allows for multicenter patient-reported outcomes research.

Sleep quality in temporomandibular disorder cases

OBJECTIVE

The aim of this study was to characterize self-reported sleep quality (SQ) in cases with temporomandibular disorder (TMD) and to compare their results with those of healthy controls.

METHODS

The Pittsburgh Sleep Quality Index (PSQI) was used to measure SQ in a convenience sample of 609 TMD cases and 88 controls. The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I diagnostic nomenclature was used, but Axis I diagnoses were based on the consensus of two reliable criterion examiners and not the RDC/TMD algorithms. The PSQI scores for TMD cases were calculated also for the RDC/TMD Axis II measures assessing chronic pain and disability, depression, and nonspecific physical symptoms. PSQI scores of the TMD cases were compared with those from controls.

RESULTS

TMD cases with one to five TMD diagnoses (n = 609) had a mean PSQI score of 7.0 [95% confidence interval (CI) = 6.7-7.4]. In comparison, the mean score was 5.2 (95% CI = 4.6-5.9) for control subjects. For the subset of TMD cases with pain-free diagnoses (n = 113), the PSQI score was similar to controls with 5.1 (95% CI = 4.5-5.6), whereas it was significantly different for cases with pain-related diagnoses 7.5 (95% CI = 6.6-8.3; n = 87). Although the number of TMD diagnoses and participant age had some influence on SQ, psychosocial status, and pain-related impairment assessed with RDC/TMD Axis II measures had the strongest association with SQ, in particular, dysfunctional chronic pain.

CONCLUSION

SQ is impaired in TMD patients with pain-related diagnoses, and even more in those with dysfunctional pain. This relationship between sleep and pain suggests that SQ should be assessed in TMD pain patients, especially in those with significant Axis II involvement.

Dopamine in plasma - a biomarker for myofascial TMD pain?

Background

Dopaminergic pathways could be involved in the pathophysiology of myofascial temporomandibular disorders (M-TMD). This study investigated plasma levels of dopamine and serotonin (5-HT) in patients with M-TMD and in healthy subjects.

Methods

Fifteen patients with M-TMD and 15 age- and sex-matched healthy subjects participated. The patients had received an M-TMD diagnosis according to the Research Diagnostic Criteria for TMD. Perceived mental stress, pain intensity (0–100-mm visual analogue scale), and pressure pain thresholds (PPT, kPa) over the masseter muscles were assessed; a venous blood sample was taken.

Results

Dopamine in plasma differed significantly between patients with M-TMD (4.98 ± 2.55 nM) and healthy controls (2.73 ± 1.24 nM; P < 0.01). No significant difference in plasma 5-HT was observed between the groups (P = 0.75). Patients reported significantly higher pain intensities (P < 0.001) and had lower PPTs (P < 0.01) compared with the healthy controls. Importantly, dopamine in plasma correlated significantly with present pain intensity (r = 0.53, n = 14, P < 0.05) and perceived mental stress (r = 0.34, n = 28, P < 0.05).

Conclusions

The results suggest that peripheral dopamine might be involved in modulating peripheral pain. This finding, in addition to reports in other studies, suggests that dopaminergic pathways could be implicated in the pathophysiology of M-TMD but also in other chronic pain conditions. More research is warranted to elucidate the role of peripheral dopamine in the pathophysiology of chronic pain.

Pain Mechanisms and Centralized Pain in Temporomandibular Disorders

Until recently, most clinicians and scientists believed that the experience of pain is perceptually proportional to the amount of incoming peripheral nociceptive drive due to injury or inflammation in the area perceived to be painful. However, many cases of chronic pain have defied this logic, leaving clinicians perplexed as to how patients are experiencing pain with no obvious signs of injury in the periphery. Conversely, there are patients who have a peripheral injury and/or inflammation but little or no pain. What makes some individuals experience intense pain with minimal peripheral nociceptive stimulation and others experience minimal pain with serious injury? It is increasingly well accepted in the scientific community that pain can be generated and maintained or, through other mechanisms, suppressed by changes in the central nervous system, creating a complete mismatch between peripheral nociceptive drive and perceived pain. In fact, there is no known chronic pain condition where the observed extent of peripheral damage reproducibly engenders the same level of pain across individuals. Temporomandibular disorders (TMDs) are no exception. This review focuses on the idea that TMD patients range on a continuum-from those whose pain is generated peripherally to those whose pain is centralized (i.e., generated, exacerbated, and/or maintained by central nervous system mechanisms). This article uses other centralized chronic pain conditions as a guide, and it suggests that the mechanistic variability in TMD pain etiology has prevented us from adequately treating many individuals who are diagnosed with the condition. As the field moves forward, it will be imperative to understand each person's pain from its own mechanistic standpoint, which will enable clinicians to deliver personalized medicine to TMD patients and eventually provide relief in even the most recalcitrant cases.

Relationship among perceived stress, anxiety, depression and craniocervical pain in nursing professionals under stress at work

Abstract Introduction: The appearance and evolution of some clinical pain conditions may be influenced by stress and other psychosocial factors. Face, head and cervical muscles may increase their activity and tension in the presence of stress, leading to craniocervicomandibular pain in individuals exposed to stress. Objective: To assess the relationship among perceived stress, anxiety, depression and craniocervicomandibular pain in nursing professionals under stress at work. Materials and Methods: Forty-three women under stress at work, according to the Job Stress Scale (JSS), were assessed by the Perceived Stress Scale (PSS), the Hospital Anxiety and Depression Scale (HADS), pressure pain threshold, measured by algometry, and muscle sensitivity to hand palpation of the masticatory and cervical muscles. Results: A low moderate level of perceived stress was found in 62.79% of the sample, anxiety in 11.63% and depression in 9.30%. The psychosocial scales correlated with each other. No correlation was found between pressure pain threshold and perceived stress, anxiety and depression. The level of pain to hand palpation correlated with the perceived stress scores. Conclusion: Pressure pain threshold was not influenced by the psychosocial factors assessed. Pain intensity to hand palpation, however, was higher as the perception of stress increased.

Disfunção temporomandibular e dor craniocervical em profissionais da área da enfermagem sob estresse no trabalho

RESUMO Objetivo: verificar a presença e severidade de Disfunção Temporomandibular, presença de cefaleia e cervicalgia e o limiar de dor muscular de músculos cervicais em profissionais de enfermagem sob estresse no trabalho. Métodos: 43 mulheres foram avaliadas quanto à presença e severidade de Disfunção Temporomandibular pelo instrumento Critérios de Diagnóstico para Pesquisa de Desordem Temporomandibular e pelo Índice Temporomandibular, respectivamente. Além disso, foram avaliadas quanto ao limiar de dor à pressão nos músculos cervicais por algometria e quanto à presença de cefaleia e cervicalgia. Resultados: disfunção Temporomandibular foi encontrada em 30,23% da amostra, com valor médio de escore de gravidade de 0,52. Entre as participantes com Disfunção Temporomandibular, 69,23% apresentavam depressão, 61,64% graduação I de dor crônica e Sintomas Físicos não Específicos incluindo e excluindo itens de dor em 46,15% e 61,64%, respectivamente. Cefaleia foi referida por 55,81% e cervicalgia por 60,47%. Não houve associação entre Disfunção Temporomandibular, cefaleia e cervicalgia. Os limiares de dor dos músculos cervicais apresentaram-se baixos tanto nos indivíduos com diagnóstico de Disfunção Temporomandibular quanto nos sem este diagnóstico, sem diferença significativa. O músculo esternocleidomastóideo apresentou-se com os menores limiares de dor à pressão. Conclusão: alta incidência de Disfunção Temporomandibular, cefaleia e cervicalgia foram detectadas nesta amostra. Disfunção Temporomandibular não influenciou a presença de cefaleia e/ou cervicalgia. A alta frequência de dor cervical e os baixos limiares de dor no músculo esternocleidomastóideo em todas as participantes demonstram o comprometimento dos músculos cervicais, resultante de possíveis posturas inadequadas e tensão muscular relacionadas ao estresse.

Aspectos clínicos e psicossociais avaliados por critérios de diagnóstico para disfunção temporomandibular

RESUMO Objetivo: analisar a associação entre a classificação de diagnósticos clínicos (dor miofascial, desordem discal e articular) e a graduação de dor crônica, depressão e sintomas físicos não específicos em sujeitos com disfunção temporomandibular. Métodos: foram incluídos 32 pacientes, com média de idade de 28,71±4,66 anos. Como instrumento de avaliação, foi utilizado o Critério de Diagnóstico para Pesquisa das Desordens Temporomandibulares - Eixo I e II. Quanto ao grupo diagnóstico, 88,13% dos indivíduos apresentaram diagnóstico misto, sendo 43,75% dos grupos I e III (distúrbios musculares e articulares) e 34,38% dos grupos I, II e III (distúrbios musculares, articulares e deslocamento de disco). Resultados: de acordo com o eixo II, 96,88% dos participantes foram classificados com dor crônica grau I e II (baixa incapacidade e baixa intensidade; baixa incapacidade e alta intensidade). Graus moderado e grave de depressão foram observados em 84,38% dos participantes. Na avaliação de sintomas físicos não específicos incluindo e excluindo dor, respectivamente, 59,38% apresentaram sintomas severos e 71,88% apresentaram sintomas moderados e severos. Verificou-se relação significante dos diagnósticos clínicos de disfunção temporomandibular com o grau de sintomas físicos não específicos incluindo dor. Conclusão: alguns aspectos clínicos e psicossociais estão associados em pacientes com disfunção temporomandibular, observando uma multiplicidade de diagnósticos clínicos com a presença de uma relação significante entre os diagnósticos clínicos encontrados e a presença de sintomas físicos inespecíficos com dor. Queixa de maior gravidade de sintomas físicos foi encontrada em pacientes com diagnóstico clínico múltiplo.

Pain-Related Temporomandibular Disorder - Current Perspectives and Evidence-Based Management

Pain-related temporomandibular disorder (TMD) is one of the top three most common chronic pain conditions, along with headaches and back pain. TMD has complex pathophysiology and significant associations with a variety of other chronic pain conditions, eg fibromyalgia, irritable bowel syndrome and migraine. Chronic TMD is associated with a negative impact upon quality of life and high levels of healthcare utility. It is important that clinicians are able to diagnose TMD correctly, provide appropriate management in keeping with current evidence-based practice, and identify when to refer patients to specialist care. The presence of risk factors, eg anxiety, depression, pain-related disability and chronic pain conditions elsewhere in the body, may help to identify which TMD patients require referral for multidisciplinary management. TMD should be managed using a holistic approach, incorporating patient education and encouragement towards self-management. TMD care pathways should consider using the three'pillars'of pain management: physical therapies, pharmacotherapy and clinical psychology.

A systematic review of the comorbidity between Temporomandibular Disorders and Chronic Fatigue Syndrome

The most common cause of chronic oro-facial pain is a group of disorders collectively termed temporomandibular disorders (TMDs). Chronic painful TMD is thought to be a 'central sensitivity syndrome' related to hypersensitivity of the nervous system, but the cause is unknown. A similar understanding is proposed for other unexplained conditions, including chronic fatigue syndrome (CFS). Exploring the comorbidity of the two conditions is a valuable first step in identifying potential common aetiological mechanisms or treatment targets.

METHOD

Systematic literature review. Studies were included if they recruited community or control samples and identified how many reported having both TMD and CFS, or if they recruited a sample of patients with either TMD or CFS and measured the presence of the other condition.

RESULTS

Six papers met inclusion criteria. In studies of patients with CFS (n = 3), 21-32% reported having TMD. In a sample of people with CFS and fibromyalgia, 50% reported having TMD. Studies in people with TMD (n = 3) reported 0-43% having CFS. Studies in samples recruited from oro-facial pain clinics (n = 2) reported a lower comorbidity with CFS (0-10%) than a study that recruited individuals from a TMD self-help organisation (43%).

CONCLUSION

The review highlights the limited standard of evidence addressing the comorbidity between oro-facial pain and CFS. There is a valuable signal that the potential overlap in these two conditions could be high; however, studies employing more rigorous methodology including standardised clinical assessments rather than self-report of prior diagnosis are needed.

Natural history of comorbid orofacial pain among women with vestibulodynia

OBJECTIVES

We evaluated the stability of the comorbidity between vulvodynia and orofacial pain (OFP) and its associated clinical characteristics over a 2-year follow-up period.

MATERIALS AND METHODS

In an earlier study of vestibulodynia patients, we administered questionnaires assessing demographic data, self-reported pain, anxiety, somatic awareness, and presence of signs and symptoms suggestive of clinical and subclinical OFP. The present study readministered the same surveys to a subset of the original cohort after a 2-year follow-up period.

RESULTS

Of the 138 women in the previous study, 71 (51%) agreed to participate in the present study. We confirmed our earlier findings that (1) OFP is a highly prevalent (66%) condition among women with vestibulodynia, and (2) compared with women with no OFP symptoms, those with OFP symptoms experience higher levels of anxiety (P=0.005) and somatic awareness (P<0.001). Although OFP symptoms showed improvement in many of the vestibulodynia patients (33%) with OFP symptoms at baseline, 13% had either developed new symptoms or transitioned from subclinical to clinical OFP classification. Intercourse-related pain decreased in 69% of patients and increased in 24% of patients. Consistent with our earlier report, we did not observe significant differences with respect to demographics or severity of pain during intercourse among the subgroups.

DISCUSSION

OFP is a common comorbidity among women with vestibulodynia, although the presence of OFP can vary over time. The comorbidity between vestibulodynia and OFP suggests that common underlying mechanisms may mediate both conditions.

Parameter estimation in Cox models with missing failure indicators and the OPPERA study

In a prospective cohort study, examining all participants for incidence of the condition of interest may be prohibitively expensive. For example, the "gold standard" for diagnosing temporomandibular disorder (TMD) is a physical examination by a trained clinician. In large studies, examining all participants in this manner is infeasible. Instead, it is common to use questionnaires to screen for incidence of TMD and perform the "gold standard" examination only on participants who screen positively. Unfortunately, some participants may leave the study before receiving the "gold standard" examination. Within the framework of survival analysis, this results in missing failure indicators. Motivated by the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study, a large cohort study of TMD, we propose a method for parameter estimation in survival models with missing failure indicators. We estimate the probability of being an incident case for those lacking a "gold standard" examination using logistic regression. These estimated probabilities are used to generate multiple imputations of case status for each missing examination that are combined with observed data in appropriate regression models. The variance introduced by the procedure is estimated using multiple imputation. The method can be used to estimate both regression coefficients in Cox proportional hazard models as well as incidence rates using Poisson regression. We simulate data with missing failure indicators and show that our method performs as well as or better than competing methods. Finally, we apply the proposed method to data from the OPPERA study.

Perspectives on next steps in classification of oro-facial pain - part 1: role of ontology

The purpose of this study was to review existing principles of oro-facial pain classifications and to specify design recommendations for a new system that would reflect recent insights in biomedical classification systems, terminologies and ontologies. The study was initiated by a symposium organised by the International RDC/TMD Consortium Network in March 2013, to which the present authors contributed. The following areas are addressed: problems with current classification approaches, status of the ontological basis of pain disorders, insufficient diagnostic aids and biomarkers for pain disorders, exploratory nature of current pain terminology and classification systems, and problems with prevailing classification methods from an ontological perspective. Four recommendations for addressing these problems are as follows: (i) develop a hypothesis-driven classification structure built on principles that ensure to our best understanding an accurate description of the relations among all entities involved in oro-facial pain disorders; (ii) take into account the physiology and phenomenology of oro-facial pain disorders to adequately represent both domains including psychosocial entities in a classification system; (iii) plan at the beginning for field-testing at strategic development stages; and (iv) consider how the classification system will be implemented. Implications in relation to the specific domains of psychosocial factors and biomarkers for inclusion into an oro-facial pain classification system are described in two separate papers.

Specific and number of comorbidities are associated with increased levels of temporomandibular pain intensity and duration

Background

Temporomandibular pain disorder (TMD) is a common pain condition in the face. People with TMD report multiple pain comorbidities. The presence of fibromyalgia and migraine in people with TMD is associated with an increase in TMD pain intensity and duration. However, data on the relationship between increasing number of pain comorbidities and TMD pain are rare. The aims of this study were: firstly to evaluate the extent to which increasing number of comorbidities is associated with increasing TMD pain intensity and duration; and secondly to evaluate the extent to which the presence of specific comorbidities is associated with increasing TMD pain intensity and duration.

Methods

The sample included 180 people seeking TMD treatment at Boston and Montreal clinics. TMD was diagnosed using the Research Diagnostic Criteria for TMD. A Numerical Pain Rating Scale assessed TMD pain intensity and participants provided their TMD pain duration in a study questionnaire. The comorbidities of migraine, chronic fatigue syndrome, irritable bowel syndrome, interstitial cystitis and restless leg syndrome were diagnosed by 5 validated diagnostic questionnaires. The associations were analyzed by linear regression, controlling for confounders.

Results

There was a positive association between the number of comorbidities present and TMD pain intensity (p < 0.01) and between the number of comorbidities present and TMD pain duration (p < 0.01). Also, the presence of migraine was positively associated with TMD pain intensity (p < 0.01) and the presence of chronic fatigue syndrome was positively associated with TMD pain intensity (p < 0.05) and with TMD pain duration (p < 0.01). When TMD patients were separated into groups, these associations did not change for the myofascial pain group, whereas in the non-myofascial pain group, the relationship between number of comorbidities and TMD pain duration was the only one still present.

Conclusion

This study shows that the number of comorbidities is positively associated with TMD pain duration and intensity. The presence of specific conditions, such as migraine and chronic fatigue syndrome, is associated with an increase in TMD intensity and duration.

The influence of emotional state on the masticatory muscles function in the group of young healthy adults

Stress may affect the function of all the components of the masticatory system and may ultimately lead to differentiated symptoms and finally to systemic and structural dysfunctions. Objective. To determine the effect of stress on the masticatory muscles function in young healthy adults. Material and Methods. A total of 201 young, Angle's first class, healthy volunteers, 103 female and 98 male, in the age between 18 and 21 years were recruited into the study. All the participants underwent clinical examination according to the Slavicek scheme, questionnaire survey according to Perceived Stress Scale, and assessment of masticatory muscles function in central occlusion. Results. Symptoms of masticatory system dysfunction were found in the group of 86 subjects (46,24%). All the muscles activity in central occlusion was comparable in female and male groups. Mean values of masseters activities in the group of low stress subjects (75,52 µV ± 15,97) were statistically different from the groups with medium (82,43 µV ± 15,04) and high (81,33 ± 12,05) perceived stress (P < 0.05). Conclusion. Chronic stress may reveal or exacerbate symptoms of masticatory dysfunction.

Norepinephrine Regulates Condylar Bone Loss via Comorbid Factors

Degenerative changes of condylar subchondral bone occur frequently in temporomandibular disorders. Although psychologic stresses and occlusal abnormalities have been implicated in temporomandibular disorder, it is not known if these risks represent synergistic comorbid factors that are involved in condylar subchondral bone degradation that is regulated by the sympathetic nervous system. In the present study, chronic immobilization stress (CIS), chemical sympathectomy, and unilateral anterior crossbite (UAC) were sequentially applied in a murine model. Norepinephrine contents in the subjects' serum and condylar subchondral bone were detected by ELISA; bone and cartilage remodeling parameters and related gene expression in the subchondral bone were examined. Subchondral bone loss and increased subchondral bone norepinephrine level were observed in the CIS and UAC groups. These groups exhibited decreased bone mineral density, volume fraction, and bone formation rate; decreased expressions of osterix, collagen I, and osteocalcin; but increased trabecular separation, osteoclast number and surface, and RANKL expression. Combined CIS + UAC produced more severe subchondral bone loss, higher bone norepinephrine level, and decreased chondrocyte density and cartilage thickness when compared to CIS or UAC alone. Sympathectomy simultaneously prevented subchondral bone loss and decreased bone norepinephrine level in all experimental subgroups when compared to the vehicle-treated counterparts. Norepinephrine also decreased mRNA expression of osterix, collagen I, and osteocalcin by mesenchymal stem cells at 7 and 14 d of stimulation and increased the expression of RANKL and RANKL/OPG ratio by mesenchymal stem cells at 2 h. In conclusion, CIS and UAC synergistically promote condylar subchondral bone loss and cartilage degradation; such processes are partially regulated by norepinephrine within subchondral bone.

Masticatory sensory-motor changes after an experimental chewing test influenced by pain catastrophizing and neck-pain-related disability in patients with headache attributed to temporomandibular disorders

Background

Recent research has shown a relationship of craniomandibular disability with neck-pain-related disability has been shown. However, there is still insufficient information demonstrating the influence of neck pain and disability in the sensory-motor activity in patients with headache attributed to temporomandibular disorders (TMD). The purpose of this study was to investigate the influence of neck-pain-related disability on masticatory sensory-motor variables.

Methods

An experimental case–control study investigated 83 patients with headache attributed to TMD and 39 healthy controls. Patients were grouped according to their scores on the neck disability index (NDI) (mild and moderate neck disability). Initial assessment included the pain catastrophizing scale and the Headache Impact Test-6. The protocol consisted of baseline measurements of pressure pain thresholds (PPT) and pain-free maximum mouth opening (MMO). Individuals were asked to perform the provocation chewing test, and measurements were taken immediately after and 24 hours later. During the test, patients were assessed for subjective feelings of fatigue (VAFS) and pain intensity.

Results

VAFS was higher at 6 minutes (mean 51.7; 95% CI: 50.15-53.26) and 24 hours after (21.08; 95% CI: 18.6-23.5) for the group showing moderate neck disability compared with the mild neck disability group (6 minutes, 44.16; 95% CI 42.65-45.67/ 24 hours after, 14.3; 95% CI: 11.9-16.7) and the control group. The analysis shows a decrease in the pain-free MMO only in the group of moderate disability 24 hours after the test. PPTs of the trigeminal region decreased immediately in all groups, whereas at 24 hours, a decrease was observed in only the groups of patients. PPTs of the cervical region decreased in only the group with moderate neck disability 24 hours after the test. The strongest negative correlation was found between pain-free MMO immediately after the test and NDI in both the mild (r = −0.49) and moderate (r = −0.54) neck disability groups. VAFS was predicted by catastrophizing, explaining 17% of the variance in the moderate neck disability group and 12% in the mild neck disability group.

Conclusion

Neck-pain-related disability and pain catastrophizing have an influence on the sensory-motor variables evaluated in patients with headache attributed to TMD.

Chronicity factors of temporomandibular disorders: a critical review of the literature

Facial pain often persists long after any identifiable organic pathology has healed. Moreover, in a subgroup of patients with temporomandibular disorder (TMD), no treatment is effective. Knowledge of factors associated with persistent pain in TMD could help identify personalized treatment approaches. Therefore, we conducted a critical review of the literature for the period from January 2000 to December 2013 to identify factors related to TMD development and persistence. The literature findings showed that chronic TMD is marked by psychological distress (somatization and depression, affective distress, fear of pain, fear of movement, and catastrophizing) and characteristics of pain amplification (hyperalgesia and allodynia). Furthermore, these factors seem to interact in TMD development. In addition, our review demonstrates that upregulation of the serotonergic pathway, sleep problems, and gene polymorphisms influence the chronicity of TMD. We conclude that psychological distress and pain amplification contribute to chronic TMD development, and that interactions among these factors complicate pain management. These findings emphasize the importance of multidisciplinary assistance in TMD treatment.

Associations between craniomandibular disorders, sociodemographic factors and self-perceived general and oral health in an adult population

OBJECTIVE

The aim of this study was to analyze the relationships between pain in the craniomandibular region and jaw dysfunction, respectively, to sociodemographic factors and self-perceived general and oral health in a middle-aged and elderly population in Västerbotten County, Sweden.

MATERIALS AND METHODS

Six hundred individuals, 35-, 50-, 65- and 75 years old, from inland and 600 individuals from coastal areas were randomly selected in 2002. Of these, 987 individuals completed a questionnaire and 779 participated in a clinical examination. Thirty-five- and 50-year-olds together constituted a middle-aged group and the rest an elderly group.

RESULTS

Among the middle-aged, craniomandibular pain was associated with impaired general health status, signs of temporomandibular disorder (TMD) pain were associated with female gender and living alone, jaw dysfunction symptoms were associated with university degree and chewing with caution; and signs of TMD dysfunction were associated with female gender and living in the more densely populated coastal region. Among the elderly, craniomandibular pain was more common among those living in the inland region, craniomandibular pain and signs of TMD pain were associated with impaired general health status, jaw dysfunction symptoms were associated with higher education level and self-perceived impaired general health and oral health; and signs of TMD dysfunction were associated with female gender and living in the coastal region. Dental status was not associated with craniomandibular pain.

CONCLUSIONS

Socioeconomic factors and impaired general state of health were related to signs and symptoms indicative of CMD. These factors may influence demand for treatment among the affected.

Observer trait anxiety is associated with response bias to patient facial pain expression independent of pain catastrophizing

Nonverbal communication, such as facial expression, is an important component of the communication of pain to an observer. One factor that influences pain perception by an observer is characteristics specific to the observer themselves (ie, ‘top-down’ characteristics). The authors of this article aimed to assess how anxiety in the observer affects their ability to rate a sufferer’s pain, controlling for pain catastrophizing.

BACKGROUND:

Top-down characteristics of an observer influence the detection and estimation of a sufferer’s pain. A comprehensive understanding of these characteristics is important because they influence observer helping behaviours and the sufferer’s experience of pain.

OBJECTIVES:

To examine the hypothesis that individuals who score high in trait anxiety would perceive more intense pain in others, as indicated by a larger negative response bias, and that this association would persist after adjusting for pain catastrophizing.

METHODS:

Healthy young adult participants (n=99; 50 male) watched videos containing excerpts of facial expressions taken from patients with shoulder pain and were asked to rate how much pain the patient was experiencing using an 11-point numerical rating scale. Sensitivity and response bias were calculated using signal detection methods.

RESULTS:

Trait anxiety was a predictor of response bias after statistically adjusting for pain catastrophizing and observer sex. More anxious individuals had a proclivity toward imputing greater pain to a sufferer.

CONCLUSIONS:

Individuals scoring higher on trait anxiety were more likely to impute pain to a sufferer. Anxious caregivers may be better able to respond with appropriate intervention once pain behaviour is detected, or they may exacerbate symptoms by engaging in excessive palliative care and solicitous behaviour.

Correlation of Anxiety Levels between Temporomandibular Disorder Patients and Normal Subjects

Background. Temporomandibular disorders (TMDs) are among the common musculoskeletal conditions affecting the individual. Anxiety plays an important role in the pathogenesis of TMD. Modern lifestyle and work environment bring to focus the role of anxiety in everyday life which is changing the demographics of diseases like TMD. This study compared the anxiety scores between TMD patients and normal subjects. Material and Methods. 505 individuals were included in the study who were divided into group 1 with 255 individuals presenting with signs and symptoms of TMD and group 2 with 250 normal individuals as controls. Hospital anxiety depression scale was used to calculate the anxiety scores. Fischer’s t test was used to compare the anxiety scores between the two groups. Results. 80% of individuals in group 2 and 44% in group 1 individuals had normal anxiety scores. 45% of the individuals in group 1 and 19% in group 2 had borderline anxiety scores. 11% of group 1 individuals and <1% of group 2 individuals demonstrated high anxiety scores. These results were statistically significant. Conclusion. Individuals with TMD exhibited higher levels of anxiety scores whereas significant number of control subjects exhibited normal anxiety scores.

The MAPP research network: a novel study of urologic chronic pelvic pain syndromes

Urologic chronic pelvic pain syndrome (UCPPS) may be defined to include interstitial cystitis/bladder pain syndrome (IC/BPS) and chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS). The hallmark symptom of UCPPS is chronic pain in the pelvis, urogenital floor, or external genitalia often accompanied by lower urinary tract symptoms. Despite numerous past basic and clinical research studies there is no broadly identifiable organ-specific pathology or understanding of etiology or risk factors for UCPPS, and diagnosis relies primarily on patient reported symptoms. In addition, there are no generally effective therapies. Recent findings have, however, revealed associations between UCPPS and “centralized” chronic pain disorders, suggesting UCPPS may represent a local manifestation of more widespread pathology in some patients. Here, we describe a new and novel effort initiated by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the U.S. National Institutes of Health (NIH) to address the many long standing questions regarding UCPPS, the Multidisciplinary Approach to the Study of Chronic Pelvic Pain (MAPP) Research Network. The MAPP Network approaches UCPPS in a systemic manner, in which the interplay between the genitourinary system and other physiological systems is emphasized. The network’s study design expands beyond previous research, which has primarily focused on urologic organs and tissues, to utilize integrated approaches to define patient phenotypes, identify clinically-relevant subgroups, and better understand treated natural history and pathophysiology. Thus, the MAPP Network provides an unprecedented, multi-layered characterization of UCPPS. Knowledge gained is expected to provide important insights into underlying pathophysiology, a foundation for better segmenting patients for future clinical trials, and ultimately translation into improved clinical management. In addition, the MAPP Network’s integrated multi-disciplinary research approach may serve as a model for studies of urologic and non-urologic disorders that have proven refractory to past basic and clinical study.

Summary of findings from the OPPERA prospective cohort study of incidence of first-onset temporomandibular disorder: implications and future directions

Papers in this issue investigate when and how putative risk factors influence development of first-onset, painful temporomandibular disorder (TMD). The results represent first findings from the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) prospective cohort study that monitored 2,737 men and women aged 18 to 44 years recruited at 4 U.S. study sites. During a median 2.8-year follow-up period, 260 participants developed TMD. The average incidence rate of 4% per annum was influenced by a broad range of phenotypic risk factors including sociodemographic characteristics, health status, clinical orofacial factors, psychological functioning, pain sensitivity, and cardiac autonomic responses. A novel method of multivariable analysis used random forest models to simultaneously evaluate contributions of all 202 phenotypic variables. Variables from the health status domain made the greatest contribution to TMD incidence, followed closely by psychological and clinical orofacial domains. However, only a few measures of pain sensitivity and autonomic function contributed to TMD incidence, and their effects were modest. Meanwhile, age and study site were independent predictors of TMD incidence, even after controlling for other phenotypes. Separate analysis of 358 genes that regulate pain found several novel genetic associations with intermediate phenotypes that, themselves, are risk factors for TMD, suggesting new avenues to investigate biological pathways contributing to TMD.

PERSPECTIVE

Collectively, the papers in this issue demonstrate that TMD is a complex disorder with multiple causes consistent with a biopsychosocial model of illness. It is a misnomer and no longer appropriate to regard TMD solely as a localized orofacial pain condition.

Multivariable modeling of phenotypic risk factors for first-onset TMD: the OPPERA prospective cohort study

Incidence of temporomandibular disorder (TMD) was predicted with multivariable models that used putative risk factors collected from initially TMD-free individuals in the Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) study. The 202 baseline risk factors included sociodemographic and clinical characteristics, measures of general health status, experimental pain sensitivity, autonomic function, and psychological distress. Study participants (n = 2,737) were then followed prospectively for a median of 2.8 years to ascertain cases of first-onset TMD. Lasso regression and random forest models were used to predict incidence of first-onset TMD using all of the aforementioned measures. Variable importance scores identified the most important risk factors, and their relationship with TMD incidence was illustrated graphically using partial dependence plots. Two of the most important risk factors for elevated TMD incidence were greater numbers of comorbid pain conditions and greater extent of nonspecific orofacial symptoms. Other important baseline risk factors were preexisting bodily pain, heightened somatic awareness, and greater extent of pain in response to examiners' palpation of the head, neck, and body. Several demographic variables persisted as risk factors even after adjusting for other OPPERA variables, suggesting that environmental variables not measured in OPPERA may also contribute to first-onset TMD.

PERSPECTIVE

Multivariable methods were used to identify the most important predictors of first-onset TMD in the OPPERA study. Important variables included comorbid pain conditions, preexisting pain, and somatic awareness. Demographic characteristics, which probably reflect environmental variables not measured in OPPERA, also appear to play an important role in the etiology of TMD.

Genetic variants associated with development of TMD and its intermediate phenotypes: the genetic architecture of TMD in the OPPERA prospective cohort study

Genetic risk factors are believed to combine with environmental exposures and contribute to the risk of developing temporomandibular disorder (TMD). In this prospective cohort study, 2,737 people without TMD were assessed for common genetic variation in 358 genes known to contribute to nociceptive pathways, inflammation, and affective distress. During a median follow-up period of 2.8 years, 260 people developed first-onset TMD. Hazard ratios were computed as measures of association between 2,924 single-nucleotide polymorphisms and TMD incidence. After correction for multiple testing, no single single-nucleotide polymorphism was significantly associated with risk of onset TMD. However, several single-nucleotide polymorphisms exceeded Bonferroni correction for multiple comparison or false discovery rate thresholds (.05, .1, or .2) for association with intermediate phenotypes shown to be predictive of TMD onset. Nonspecific orofacial symptoms were associated with voltage-gated sodium channel, type I, alpha subunit (SCN1A, rs6432860, P = 2.77 × 10(-5)) and angiotensin I-converting enzyme 2 (ACE2, rs1514280, P = 4.86 × 10(-5)); global psychological symptoms with prostaglandin-endoperoxide synthase 1 (PTGS1, rs3842803, P = 2.79 × 10(-6)); stress and negative affectivity with amyloid-β (A4) precursor protein (APP, rs466448, P = 4.29 × 10(-5)); and heat pain temporal summation with multiple PDZ domain protein (MPDZ, rs10809907, P = 3.05 × 10(-5)). The use of intermediate phenotypes for complex pain diseases revealed new genetic pathways influencing risk of TMD.

PERSPECTIVE

This article reports the findings of a large candidate gene association study of first-onset TMD and related intermediate phenotypes in the OPPERA Study. Although no genetic markers predicted TMD onset, several genetic risk factors for clinical, psychological, and sensory phenotypes associated with TMD onset were observed.

Study protocol, sample characteristics, and loss to follow-up: the OPPERA prospective cohort study

When studying incidence of pain conditions such as temporomandibular disorder (TMD), repeated monitoring is needed in prospective cohort studies. However, monitoring methods usually have limitations and, over a period of years, some loss to follow-up is inevitable. The OPPERA prospective cohort study of first-onset TMD screened for symptoms using quarterly questionnaires and examined symptomatic participants to definitively ascertain TMD incidence. During the median 2.8-year observation period, 16% of the 3,263 enrollees completed no follow-up questionnaires, others provided incomplete follow-up, and examinations were not conducted for one third of symptomatic episodes. Although screening methods and examinations were found to have excellent reliability and validity, they were not perfect. Loss to follow-up varied according to some putative TMD risk factors, although multiple imputation to correct the problem suggested that bias was minimal. A second method of multiple imputation that evaluated bias associated with omitted and dubious examinations revealed a slight underestimate of incidence and some small biases in hazard ratios used to quantify effects of risk factors. Although "bottom line" statistical conclusions were not affected, multiply-imputed estimates should be considered when evaluating the large number of risk factors under investigation in the OPPERA study.

PERSPECTIVE

These findings support the validity of the OPPERA prospective cohort study for the purpose of investigating the etiology of first-onset TMD, providing the foundation for other papers investigating risk factors hypothesized in the OPPERA project.

The effects of ULF-TENS stimulation on gnathology: the state of the art

AIMS

The aim of this study was to evaluate the state of the art in the current literature regarding the effect of ultra low frequency-transcutaneous electrical nerve stimulation (ULF-TENS) on patients with temporomandibular disorders (TMD).

METHODOLOGY

The authors reviewed the literature through a thorough manual and electronic research on PubMed database (using the Medical Subject Headings thesaurus) and subsequent analysis of all the found papers regarding the effect of TENS on TMD patients. No randomized controlled trials on the investigated topic were found. Only eight papers regarding controlled clinical trials (CCT) were selected according to the search strategy selection criteria.

RESULTS

According to the available literature and the authors' experience, ULF-TENS seems to be a valid support in the management of TMD patients, but also a 'provocative' tool, so its application should always be monitored by electromyographic and electrognathographic analysis (before and after TENS).

CONCLUSIONS

Further clinical studies (mainly randomized controlled trials) on ULF-TENS application in neuromuscular gnathology are needed.

The importance of psychological assessment in chronic pain

PURPOSE OF REVIEW

Much confusion has surrounded the purpose of the psychological assessment in the context of chronic pain. For many clinicians, the psychological assessment is used to rule out psychiatric illness and to identify the nonmedical causes for pain and disability. In essence, it is used to identify the causes of pain that fall outside of the biomedical model. Supported by over 30 years of evidence, the bio-psycho-social model acknowledges that psychosocial factors are inherent in chronic pain and require assessment if meaningful diagnostics and treatments are to occur.

RECENT FINDINGS

Five broad categories of psychosocial assessment are relevant to chronic pain. These categories have been shown to enhance the diagnosis of the underlying forms of pain, predict the transition from acute to chronic status, and help to phenotype individuals for the discovery of the underlying mechanisms responsible for pain.

SUMMARY

Informed assessment of chronic pain needs to include relevant biological, psychological, and social domains. This article describes those domains and offers suggestions of specific instruments to use in clinical or research settings.

Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Group†

AIMS

The original Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) Axis I diagnostic algorithms have been demonstrated to be reliable. However, the Validation Project determined that the RDC/TMD Axis I validity was below the target sensitivity of ≥ 0.70 and specificity of ≥ 0.95. Consequently, these empirical results supported the development of revised RDC/TMD Axis I diagnostic algorithms that were subsequently demonstrated to be valid for the most common pain-related TMD and for one temporomandibular joint (TMJ) intra-articular disorder. The original RDC/TMD Axis II instruments were shown to be both reliable and valid. Working from these findings and revisions, two international consensus workshops were convened, from which recommendations were obtained for the finalization of new Axis I diagnostic algorithms and new Axis II instruments.

METHODS

Through a series of workshops and symposia, a panel of clinical and basic science pain experts modified the revised RDC/TMD Axis I algorithms by using comprehensive searches of published TMD diagnostic literature followed by review and consensus via a formal structured process. The panel's recommendations for further revision of the Axis I diagnostic algorithms were assessed for validity by using the Validation Project's data set, and for reliability by using newly collected data from the ongoing TMJ Impact Project-the follow-up study to the Validation Project. New Axis II instruments were identified through a comprehensive search of the literature providing valid instruments that, relative to the RDC/TMD, are shorter in length, are available in the public domain, and currently are being used in medical settings.

RESULTS

The newly recommended Diagnostic Criteria for TMD (DC/TMD) Axis I protocol includes both a valid screener for detecting any pain-related TMD as well as valid diagnostic criteria for differentiating the most common pain-related TMD (sensitivity ≥ 0.86, specificity ≥ 0.98) and for one intra-articular disorder (sensitivity of 0.80 and specificity of 0.97). Diagnostic criteria for other common intra-articular disorders lack adequate validity for clinical diagnoses but can be used for screening purposes. Inter-examiner reliability for the clinical assessment associated with the validated DC/TMD criteria for pain-related TMD is excellent (kappa ≥ 0.85). Finally, a comprehensive classification system that includes both the common and less common TMD is also presented. The Axis II protocol retains selected original RDC/TMD screening instruments augmented with new instruments to assess jaw function as well as behavioral and additional psychosocial factors. The Axis II protocol is divided into screening and comprehensive self report instrument sets. The screening instruments' 41 questions assess pain intensity, pain-related disability, psychological distress, jaw functional limitations, and parafunctional behaviors, and a pain drawing is used to assess locations of pain. The comprehensive instruments, composed of 81 questions, assess in further detail jaw functional limitations and psychological distress as well as additional constructs of anxiety and presence of comorbid pain conditions.

CONCLUSION

The recommended evidence-based new DC/TMD protocol is appropriate for use in both clinical and research settings. More comprehensive instruments augment short and simple screening instruments for Axis I and Axis II. These validated instruments allow for identification of patients with a range of simple to complex TMD presentations.

Exploration of dimensionality and psychometric properties of the Pittsburgh Sleep Quality Index in cases with temporomandibular disorders

BACKGROUND

This study assessed the dimensional structure of sleep quality with the Pittsburgh Sleep Quality Index (PSQI) and investigated its psychometric properties in cases with temporomandibular disorders (TMD).

METHODS

A convenience sample of 609 TMD cases (age: 37.1 ± 13.1 yrs, 18-67 yrs, 85% female) of the multi-center Validation Project meeting Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and with sufficient PSQI data were included in this study. To investigate PSQI scores' dimensionality, exploratory factor analysis was used. Factors were identified using the Scree plot. To investigate internal consistency, Cronbach's alpha was calculated. Analyses were separately performed for TMD cases with (N = 496) and TMD cases withouta pain-related diagnosis (N = 113).

RESULTS

The mean PSQI score for all TMD cases was 7.1 ± 4.0 units, range: 0-19. The exploratory factor analysis identified one factor for cases with at least one pain-related TMD diagnosis as well as one factor for cases with a pain-free TMD diagnosis that explained 41% of the variance in cases with pain-related TMD and 37% in cases with pain-free TMD. Internal consistency for PSQI scores was alpha of 0.75 in cases with pain-related TMD, alpha of 0.66 in cases with pain-free TMD and alpha = 0.75 for all TMD cases.

CONCLUSIONS

Sleep quality in TMD patients is a unidimensional construct and can therefore be represented by one summary score; a finding that is in line with previous reports in TMD patients.

Chronic HPA axis response to stress in temporomandibular disorder

PURPOSE

Perceived stress is associated with temporomandibular disorder (TMD), but whether cortisol levels are elevated in individuals with TMD is unknown. We hypothesized that cortisol concentration, a biomarker of hypothalamic-pituitary-adrenal (HPA) axis function, was elevated in TMD cases relative to controls, and that perceived stress was positively correlated with cortisol concentration.

METHODS

In this case control study, TMD case status was determined by examiners using TMD Research Diagnostic Criteria. Participants (n=116) aged 18 to 59 years were recruited from within a 50 mile radius of the University of North Carolina at Chapel Hill. Following examination, cases (n=45) and controls (n=71) completed the 14-item Perceived Stress Scale using a reference interval of the past 3 months. Approximately 100 strands of hair were cut from the posterior vertex segment of their scalp. The 3 centimeters of hair most proximal to the scalp was analyzed with a commercially available salivary cortisol enzyme immunoassay adapted for hair cortisol. This length corresponds to the last 3 months of systemic HPA axis activity.

RESULTS

TMD cases perceived higher stress than controls (p=0.001). However, hair cortisol concentration was lower in TMD cases than controls (p<0.001). The correlation coefficient revealed a weak negative relationship (r=-0.188) between perceived stress and hair cortisol concentration (p=0.044). In analysis stratified by case status, the relationship of perceived stress and hair cortisol concentration was non-significant for cases (p=0.169) and controls (p=0.498).

CONCLUSION

Despite greater perceived stress, TMD cases had lower hair cortisol concentrations than controls and the 2 measures of stress were weakly and negatively correlated.