Influence of psychological factors on risk of temporomandibular disorders

Bruxism, temporomandibular disorders, and headache-a narrative review of correlations and causalities

ABSTRACT

The co-occurrence of bruxism, temporomandibular disorders (TMDs), and headache is common in patients. However, there is conflicting evidence regarding whether this association is simply a result of their high prevalence or whether there are indeed causal relationships. This review provides an overview of the current state of research while taking into account the controversies surrounding research methods, particularly in definitions and diagnostic standards. Bruxism-defined as repetitive jaw muscle activity during sleep or wakefulness-is not a painful disorder but may-particularly in co-occurrence with TMD-worsen pre-existing headache. It seems important to differentiate between sleep and awake bruxism because of different impact on pathophysiological processes in different primary headache disorders such as migraine and tension-type headache. Temporomandibular disorder is a heterogenous entity with both myofascial and arthrogenous types of pain in addition to nonpainful disorders. Research suggests a correlation between TMD pain and migraine, as well as between awake bruxism and tension-type headache. However, psychosocial factors may act as confounders in these relationships. Determining causality is challenging because of the limited number of experimental and clinical studies conducted on this topic. The main finding is an apparent lack of consensus on the definition and assessment criteria for bruxism. Treatment wise, it is important to differentiate all 3 conditions because treatment of one condition may have an effect on the other 2 without proving causality. For future research, it is crucial to establish greater consistency and applicability in diagnostic procedures and definitions. In addition, more experimental and clinical studies investigating the question of causality are needed.

Investigating the effect of depression on clinical symptoms of temporomandibular disorder in young stressful men

OBJECTIVES

The objective of this study was to investigate the relationship of the depression level with temporomandibular disorders (TMDs) in young conscripts as a population with chronic stresses.

MATERIAL AND METHODS

A total number of 144 male conscripts with chronic stress and different levels of depression were assigned to four groups according to the Beck's Depression Inventory (BDI). The control group consisted of age-matched male conscripts without chronic stress. The diagnosis of TMD was made according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Data were analyzed using Mann-Whitney and chi-square tests.

RESULTS

The participants with severe depression were significantly more susceptible to have TMD (p = .001) followed by the moderate depression, borderline clinical depression, mild mood disturbance, and control groups. The TMD diagnoses were more prevalent within depression groups compared with the control population (p = .01).

CONCLUSIONS

The level of depression is directly associated with the presence of TMD in young men with chronic stress.

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.

Association of oral behaviours and psychological factors with selected genotypes in pain-related TMD

OBJECTIVES

To investigate frequency of single nucleotide polymorphisms (SNPs) in pain-related temporomandibular disorders (TMDp) and to determine whether specific SNPs, psychological, psychosomatic and behavioural characteristics are predictive for pain existence and intensity (low pain intensity (LPI)/high pain intensity (HPI)).

METHODS

Genomic DNA was extracted from buccal mucosa swabs (85 TMDp;85 controls) for evaluating frequency of selected SNPs: catechol-O-methyltransferase (rs4680, rs4818), opiorphin (rs1387964), alpha subunit of voltage-gated sodium channel Nav1.1 (rs6432860) and voltage-gated sodium channel Nav1.9 (rs33985936). Participants completed questionnaires on somatosensory amplification, anxiety and depression symptoms and oral behaviours (OB).

RESULTS

Sleep-related OB frequency was higher in TMDp patients compared to controls (p = 0.008). Compared to LPI, HPI patients had higher depression (p = 0.020) and anxiety scores (p = 0.017). TMDp group showed higher frequency of CC genotype (rs1387964) than controls (12.9% vs. 3.5%, p = 0.025). Following adjustments for age, sex and sleep-related OB, the significance of the recessive model (CC vs. TC + TT) between TMDp patients and controls was retained (OR = 5.783; 95%CI: 1.454-23.004). Frequency of GG genotype (rs4680 and rs4818) was higher in HPI compared to LPI patients (40% vs. 11.4%, p = 0.006; 24% vs. 3%; p = 0.012, respectively). The difference remained significant after adjusting for age, sex, depression, anxiety and sleep-related OB (rs4680: OR = 3.621; 95%CI: 1.580-8.297; rs4818: OR = 4.919, 95%CI: 1.641-14.746).

CONCLUSION

This study has demonstrated that rs1387964 CC genotype was associated with TMDp while rs4680 GG and rs4818 GG genotypes contributed to HPI.

Relationship of temporomandibular joint disorders with cervical posture and hyoid bone position

OBJECTIVE

To evaluate craniocervical posture and hyoid bone position in patients with and without temporomandibular joint disorder (TMD).

METHODS

A total of 113 people were included in the study, including 55 TMD patients and 58 healthy controls. Using lateral cephalograms, the craniofacial, craniocervical, and hyoid bone positions of the participants were evaluated in terms of 27 variables.

RESULTS

There was no significant difference in craniocervical angles between participants with or without TMD. While the Hy-B, Hy-NSL, Hy-NL measurements and FMA (°), AFH (mm) measurements of participants with TMD were lower than the control group, the hyoid angle was greater than the control group.

CONCLUSION

These study findings provide evidence that TMD is not related to craniocervical posture but to the position of the hyoid bone and craniofacial morphology.

Biobehavioral Predictors of Pain Intensity, Pain Interference, and Chronic Pain Episodes: A Prospective Cohort Study of African-American Adults

Racial disparities in pain experiences are well-established, with African-American (AA) adults reporting higher rates of daily pain, increased pain severity, and greater pain-related interference compared to non-Hispanic Whites. However, the biobehavioral factors that predict the transition to chronic pain among AA adults are not well understood. This prospective cohort study provided a unique opportunity to evaluate predictors of chronic pain onset among 130 AA adults (81 women), ages 18 to 44, who did not report chronic pain at their baseline assessment and subsequently completed follow-up assessments at 6- and 12-months. Outcome measures included pain intensity, pain-related interference, and chronic pain status. Comprehensive assessments of sociodemographic and biobehavioral factors were used to evaluate demographics, socioeconomic status, stress exposure, psychosocial factors, prolonged hypothalamic-pituitary-adrenal secretion, and quantitative sensory testing responses. At baseline, 30 adults (23.1%) reported a history of prior chronic pain. Over the 12-month follow-up period, 13 adults (10.0%) developed a new chronic pain episode, and 18 adults (13.8%) developed a recurrent chronic pain episode. Whereas socioeconomic status measures (ie, annual income, education) predicted changes in pain intensity over the follow-up period, quantitative sensory testing measures (ie, pain threshold, temporal summation of pain) predicted changes in pain interference. A history of chronic pain and higher depressive symptoms at baseline independently predicted the onset of a new chronic pain episode. The present findings highlight distinct subsets of biobehavioral factors that are differentially associated with trajectories of pain intensity, pain-related interference, and onset of chronic pain episodes in AA adults. PERSPECTIVE: This prospective study sought to advance understanding of biobehavioral factors that predicted pain outcomes over a 12-month follow-up period among AA adults without chronic pain at their initial assessment. Findings revealed distinct subsets of factors that were differentially associated with pain intensity, pain-related interference, and onset of chronic pain episodes.

Causal relationship between psychiatric traits and temporomandibular disorders: a bidirectional two-sample Mendelian randomization study

OBJECTIVES

This study was to investigate the causal relationship between temporomandibular disorders (TMD) and psychiatric disorders by Mendelian randomization (MR) analysis.

MATERIALS AND METHODS

A two-sample bidirectional MR analysis was adopted to systematically explore the causal relationship between TMD and eight psychiatric traits, including anxiety disorder (AD), panic disorder (PD), major depressive disorder (MDD), neuroticism, attention deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD), bipolar disorder (BIP), and schizophrenia (SCZ). Inverse variance weighted (IVW), weighted median, and MR-Egger regression were used in my study. Furthermore, we also performed three sensitivity analyses to illustrate the reliability of the analysis.

RESULTS

Two psychiatric traits have risk effects on TMD: PD (OR = 1.118, 95% CI: 1.047-1.194, P = 8.161 × 10-4, MDD (OR = 1.961, 95% CI: 1.450-2.653, P = 1.230 × 10-5). Despite not surpassing the strict Bonferroni correction applied (P > 0.00625), we could think that there was a suggestive causal effect of neuroticism and SCZ increasing the risk of TMD. On the reverse MR analysis, we found no significant evidence of causal effects of TMD on these psychiatric traits. Except for heterogeneity in the causal analysis for SCZ on TMD, no heterogeneity and horizontal pleiotropy were detected in the other analyses.

CONCLUSIONS

Our two-sample MR study has provided further evidence of PD and MDD being related to a higher risk of TMD.

CLINICAL RELEVANCE

These findings highlight the importance of closely monitoring mental traits during future TMD treatments to prevent an increased risk of TMD.

The Interconnection Between Social Support and Emotional Distress Among Individuals with Chronic Pain: A Narrative Review

Chronic pain is a public health concern affecting over 100 million U.S. adults. Because chronic pain is multifactorial, it requires a biopsychosocial approach to understand how biological, psychological, and social factors contribute to both the development and maintenance of pain. On average, individuals with chronic pain report higher levels of emotional distress compared to pain-free individuals. Research has demonstrated that social support is associated with better pain outcomes and less emotional distress. It has been proposed that social support may improve pain outcomes by reducing the influence of stressors. However, the majority of research exploring the relationships between social support and pain-related outcomes has focused on the direct relationship between these variables, largely overlooking the process by which social support has a positive influence on pain. This narrative review synthesizes research on how chronic pain, emotional distress, and social support are highly interconnected, yet research investigating chronic pain and emotional distress within a social context is limited. We then highlight disparities in chronic pain, such that the burden of chronic pain is unequal between demographic groups. Next, we discuss existing evidence for the use of group-based interventions to address pain-related outcomes. Lastly, we summarize limitations of prior research studies and highlight gaps in the current literature. Overall, longitudinal research comprehensively investigating the distinct nuances in the measurement of social support and how these nuances relate to emotional distress and pain outcomes is needed and may provide insight into the unique needs of individuals or subgroups. Further, demographically diverse randomized controlled trials are needed to identify the process by which group-based interventions improve pain outcomes and whether these interventions are more effective for particular groups in order to personalize treatment approaches and address inequities in pain care.

Temporomandibular disorders-review of evidence-based management and a proposed multidisciplinary care pathway

Temporomandibular disorders (TMDs) are a prevalent but complex group of conditions that cause orofacial pain. Temporomandibular disorders are recognized as one of the most common chronic pain conditions, alongside back pain and headache disorders. Given the competing theories surrounding what causes TMDs and limited high-equality evidence on optimally treating TMDs, clinicians often encounter challenges in developing an effective management plan for patients. Furthermore, patients will often seek advice from multiple health care providers from varying specialties, seeking curative management, often resulting in inappropriate treatments and no improvement in pain symptoms. Throughout this review, we explore the existing evidence base surrounding the pathophysiology, diagnosis, and management of TMDs. An existing United Kingdom-based multidisciplinary care pathway for the management of TMDs is described herein, highlighting the benefits of a multidisciplinary approach to patient care for TMDs.

Are catechol-O-methyltransferase gene polymorphisms genetic markers for pain sensitivity after all? - A review and meta-analysis

The catechol-O-methyltransferase (COMT) gene has arguably been the designated pain sensitivity gene for nearly two decades. However, the literature provides inconsistent evidence. We performed several meta-analyses including k = 31 samples and n = 4631 participants thereby revealing small effects of rs4680 on pain thresholds in fibromyalgia, headache and across chronic pain conditions. Moreover, rs4680 effects were found across pain patients when affected, but not unaffected, body sites were assessed. No effect was detected for any other SNP investigated. Importantly, our results corroborate earlier findings in that we found a small effect of COMT haplotypes on pain sensitivity. Our review and meta-analysis contribute to the understanding of COMT-dependent effects on pain perception, provide insights into research issues and offer future directions. The results support the theory that rs4680 might only impact behavioural measures of pain when descending pain modulatory pathways are sufficiently challenged. After all, COMT polymorphisms are genetic markers of pain sensitivity, albeit with some limitations which are discussed with respect to their implications for research and clinical significance.

Temporomandibular disorder severity and its association with psychosocial and sociodemographic factors in Turkish adults

BACKGROUND

There is a lack of awareness regarding temporomandibular disorder (TMD) and its association with psychological and sociodemographic factors in the Turkish population. This study aimed to evaluate the relationship between signs/symptoms of anxiety-depression, sociodemographic factors, parafunctional habits, bruxism, and the presence and severity of the symptoms of TMD in Turkish adults.

METHODS

The participants completed an online questionnaire consisting of sociodemographic questions, the Fonseca Anamnestic Index, and the Patient Health Questionnaire-4.

RESULTS

The mean age of the 2580 participants was 35.29 ± 12.70 years, and 63.3% were women. The frequency of the participants who showed symptoms of TMD was 69.8%. The severity of TMD symptoms was significantly greater in participants who had signs/symptoms of anxiety and depression (p < 0.05). Sociodemographic and psychological data showed an association between the presence and severity of the symptoms of TMD and sex (OR 1.52, 95% confidence interval (CI) 1.26-1.85), parafunctional habits (OR 2.64, 95% CI 2.36-2.99), bruxism (OR 3.14, 95% CI 1.78-4.90), signs/symptoms of anxiety (OR 2.30, 95% CI 1.76-3.00), and signs/symptoms of depression (OR 1.90, 95% CI 1.48-2.42).

CONCLUSIONS

The results of the present study suggest that females and those who report bruxism, parafunctional habits, and signs/symptoms of anxiety-depression are more likely to show symptoms of TMD with different severity.

Association between depression and temporomandibular dysfunction in adults - a systematic review

OBJECTIVE

To critically evaluate the literature and answer the question: "Is there an association between depression and temporomandibular disorder (TMD) in adults?"

METHODS

The personalized search strategy was applied to PubMed, Embase, Web of Science, and Scopus databases. Articles were selected in two stages according to the eligibility criteria. The Joanna Briggs Institute (JBI) tool was used to analyze the risk of bias according to the type of study.

RESULTS

The included articles presented a moderate risk of bias. Based on the studies, individuals with TMD have higher levels of depression compared to the control group. There is also a direct association in that individuals with depression are more susceptible to developing TMD.

CONCLUSION

There is a probable association between depression and TMD in adults. However, more studies with high methodological quality are needed to confirm this finding.

The role of pain-related disability on treatment outcome and psychosocial symptoms in patients with temporomandibular disorders - a pilot study

OBJECTIVE

The aim of the pilot study was to investigate the association of pain-related disability with the outcome of conservative treatment of temporomandibular disorders (TMD) and with depressive and non-specific physical symptoms among TMD pain patients utilizing Graded Chronic Pain Scale 1.0 (GCPS1.0) as a screening instrument.

MATERIAL AND METHODS

The study included 80 adult patients who were referred to the Oral and Maxillofacial Department, Oulu University Hospital, Finland, due to TMD pain. At baseline, pain-related disability was assessed by using the GCPS1.0 according to the Research Diagnostic Criteria for TMD (RDC/TMD), and the patients were categorized into three TMD subtypes, 1-3. Patients were given conservative TMD treatment. At follow-up visits (1, 3, 6, and 12 months), patients evaluated the pain intensity on an NRS and described the treatment outcome and the severity of the TMD symptoms on a numerical scale.

RESULTS AND CONCLUSIONS

Patients with TMD subtype 3 (moderate/severe disability) had the highest NRS scores and described their symptoms as most severe at each time point, statistically significantly so at 1-month and 6-month follow-up (p < .05). The highest proportion of depressive symptoms was found in TMD subtype 3 (p < .05). The current pilot study showed that moderate/severe TMD-related disability, based on the GCPS 1.0 as a screening tool, may be linked with poor treatment outcome and depressive symptoms. Studies with larger samples are needed to confirm the results.

Triad Multisystem Phenotype with High-risk for Developing Temporomandibular Disorders- Characteristics and Potential Pathophysiology Results from the OPPERA Dataset

ABSTRACT

A multisystem phenotype with the Triad of bodily pain, psychological distress, and sleep disturbance was found to have high risk for developing initial onset of painful temporomandibular disorders (TMDs) in the multicenter Orofacial Pain: Prospective Evaluation and Risk Assessment (OPPERA) dataset. In this study, we systemically examined phenotypic characteristics and explored potential pathophysiology in quantitative sensory testing (QST) and autonomic nervous system (ANS) domains in this multisystem Triad phenotype. Secondary analysis was performed on 1199 non-Triad and 154 Triad TMD-free OPPERA enrollees at baseline. Results indicate that prior to developing TMDs, the Triad phenotype demonstrated both orofacial and systemic signs and symptoms that can only be captured through multisystem assessment. In addition, we found significantly lower resting heart rate variability and higher resting heart rate in the Triad phenotype as compared to the non-Triad group. However, pain sensitivity measured by QST was not different between groups. These findings highlight the importance of whole-person multisystem assessment at the stage prior to developing complex pain conditions such as TMDs, and suggest that, in addition to a "tissue damage monitor", pain should be considered in a broader context, such as a component within a "distress monitoring system" at the whole-person level when multisystem issues co-present. Therefore, the presence or absence of multisystem issues may carry critical information when searching for disease mechanisms and developing mechanism-based intervention and prevention strategies for TMDs and related pain conditions. Cardiovascular autonomic function should be further researched when multisystem issues co-present prior to developing TMDs.

Ratio of Omega-6/Omega-3 Polyunsaturated Fatty Acids Associated With Somatic and Depressive Symptoms in People With Painful Temporomandibular Disorder and Irritable Bowel Syndrome

Somatic symptom disturbance is among the strongest predictors of painful temporomandibular disorder (TMD). Related psychological constructs, such as anxiety and depression, respond therapeutically to omega-3 polyunsaturated fatty acids (PUFAs) in clinical trials. This cross-sectional study investigated associations between the omega-6/omega-3 PUFA ratio and somatic symptom disturbance and depressive symptoms in a community-based sample of 501 adults and determined whether these associations differed between adults with and without TMD or irritable bowel syndrome (IBS). Liquid chromatography tandem mass spectrometry quantified PUFAs in circulating erythrocytes. Somatic symptoms and depression were quantified using Symptom Checklist-90-Revised subscales. Presence or absence of TMD and IBS, respectively, were determined by clinical examination and Rome III screening questions. The standardized beta coefficient for the omega-6/omega-3 long-chain PUFA ratio was 0.26 (95% confidence limits (CL): 0.08, 0.43) in a multivariable linear regression model in which somatic symptom disturbance was the dependent variable. When modelling depressive symptoms as the dependent variable, the standardized beta coefficient was 0.17 (95% CL:0.01, 0.34). Both associations were stronger among TMD cases and IBS cases than among non-cases. Future randomized control trials that lower the omega-6/omega-3 PUFA ratio could consider somatic or depressive symptoms as a therapeutic target for TMD or IBS pain. PERSPECTIVE: In people with TMD or IBS, a high n-6/n-3 PUFA ratio was positively associated with somatic symptom disturbance and depressive symptoms. Both measures of psychological distress were elevated in people with painful TMD and IBS. Future randomized clinical trials will determine whether lowering the n-6/n-3 ratio is therapeutic for pain.

Influence of the COVID-19 pandemic on pain and oral health-related quality of life in women with temporomandibular disorder

Objective:

This study aimed to evaluate and compare pain intensity and Oral Health-related Quality of Life (OHRQoL) in women with temporomandibular disorder (TMD) before (T1) and during (T2) COVID-19 pandemic.

Materials and Methods:

Sample was composed of forty-one female participants with painful TMD, who presented for TMD treatment. Subjects were asked to indicate their pain intensity and to answer the Oral Health Impact Profile-14 (OHIP-14). Participants data were collected twice: T1 (evaluation of medical records fulfilled before COVID-19 pandemic) and T2 (by means of an online form). Socio-demographic data were assessed in T1. Statistical analysis was performed with a significance level of 5% (Wilcoxon, chi-square or Fisher’s exact tests, multiple linear regressions).

Results:

No difference was found in pain intensity (p=0.26) and OHIP-14 global scores (p=0.53). Physical pain (p=0.03) and social disability (p=0.05) domains improved. In T1, subject’s occupation was associated with OHIP-14 global score, physical pain, and physical disability domains. In T2, age was associated with OHIP-14 global scores as well as physical pain, psychological discomfort, and psychological disability domains.

Conclusion:

COVID-19 pandemic did not worsen pain intensity and OHRQoL in women with painful TMD, and it is suggested that socio-demographic characteristics influenced TMD patients coping skills during pandemic.

Gut Bless Your Pain—Roles of the Gut Microbiota, Sleep, and Melatonin in Chronic Orofacial Pain and Depression

Background. Increased attention has been paid to the gut–brain axis recently, but little is known so far regarding how this translates into pain susceptibility. Aim. The aim of this review is to determine whether gastroenterological disorders and sleep disorders (directly or indirectly) contribute to an increased susceptibility to depression and chronic orofacial pain. Method. A search was performed in the U.S. National Library of Medicine (PubMed) database in order to find studies published before 19 December 2021. We used the following terms: gut microbiome, OR sleep quality, OR melatonin, OR GERD, OR IBS, AND: depression OR chronic pain, in different configurations. Only papers in English were selected. Given the large number of papers retrieved in the search, their findings were described and organized narratively. Results. A link exists between sleep disorders and gastroenterological disorders, which, by adversely affecting the psyche and increasing inflammation, disturb the metabolism of tryptophan and cause excessive microglial activation, leading to increased susceptibility to pain sensation and depression. Conclusions. Pain therapists should pay close attention to sleep and gastrointestinal disorders in patients with chronic pain and depression.

Animal Models of Temporomandibular Joint Osteoarthritis: Classification and Selection

Temporomandibular joint osteoarthritis (TMJOA) is a common degenerative joint disease that can cause severe pain and dysfunction. It has a serious impact on the quality of lives of patients. Since mechanism underlying the pathogenesis of TMJOA is not fully understood, the development of effective tools for early diagnosis and disease-modifying therapies has been hindered. Animal models play a key role in understanding the pathological process of diseases and evaluating new therapeutic interventions. Although some similarities in disease processes between animals and humans are known, no one animal model is sufficient for studying all characteristics of TMJOA, as each model has different translatability to human clinical conditions. For the past 4 decades, TMJOA animal models have been studied by numerous researchers and can be broadly divided into induced, naturally occurring, and genetically modified models. The induced models can be divided into invasive models (intra-articular injection and surgical induction) or non-invasive models (mechanical loading, high-fat diet, and sleep deprivation). Different types of animal models simulate different pathological expressions of TMJOA and have their unique characteristics. Currently, mice, rats, and rabbits are commonly used in the study of TMJOA. This review sought to provide a general description of current experimental models of TMJOA and assist researchers in selecting the most appropriate models for different kinds of research.

DISFUNÇÕES TEMPOROMANDIBULARES E FATORES PSICOLÓGICOS: UMA REVISÃO DE LITERATURA

As disfunções temporomandibulares (DTM) são condições biológicas que envolvem sinais e sintomas como dores crônicas na articulação temporomandibular e nos músculos da mastigação. O presente estudo tem como objetivo identificar quais e como conceitos psicológicos são descritos em artigos de intervenções odontológicas relacionadas à DTM, em artigos de revisão sistemática. Para isto foram utilizadas três bases de dados na busca e seleção: PubMed, Scopus e Web of Science. Aplicou-se em todas estas bases de dados a mesma formulação de termos-chave. Foram selecionados os artigos de revisões, publicados entre 2000 e 2017, escritos em inglês. Dos 4.092 artigos encontrados, sete foram selecionados descrevendo intervenções psicológicas envolvidas com o tratamento da DTM. Todos os artigos selecionados foram analisados com base em seus objetivos e discussões, considerando as características de apresentação e compreensão das variáveis psicológicas relacionadas à disfunção temporomandibular e às intervenções utilizadas. Para tanto, foram realizadas análises qualitativas e quantitativas. Pode-se concluir que a compreensão e a definição das variáveis psicológicas relacionadas à DTM não são evidentes, o que dificulta a produção de resultados claros sobre a eficácia dos diagnósticos e intervenções para DTM. 

The Association Between Adverse Life Events, Psychological Stress, and Pain-Promoting Affect and Cognitions in Native Americans: Results from the Oklahoma Study of Native American Pain Risk

Native Americans (NAs) experience higher rates of chronic pain. To examine the mechanisms for this pain inequity, we have previously shown that NAs report higher levels of pain-related anxiety and pain catastrophizing, which are in turn related to pronociceptive (pain-promoting) processes. But, it is currently unclear why NAs would report greater pain-related anxiety and catastrophizing. Given that NAs are also more likely to experience adverse life events (ALEs) and associated psychological distress, it was hypothesized that higher anxiety/catastrophizing in NAs would be partially explained by higher rates of ALEs and psychological distress. Structural equation modeling was used to analyze these pathways (NA ethnicity ➔ ALEs ➔ psychological distress ➔ pain anxiety/catastrophizing) in 305 healthy, pain-free adults (N = 155 NAs, N = 150 non-Hispanic Whites [NHWs]). Pain-related anxiety and situational pain catastrophizing were assessed in response to a variety of painful tasks. The Life Events Checklist was used to assess cumulative exposure to ALEs that directly happened to each participant. A latent psychological distress variable was modeled from self-reported perceived stress and psychological symptoms. Results found that NAs experienced more ALEs and greater psychological distress which was associated with higher rates of pain-related anxiety and pain catastrophizing. Notably, NAs did not report greater psychological distress when controlling for ALE exposure. This suggests that a higher risk of chronic pain in NAs may be due, in part, to psychological distress, pain-related anxiety, and pain catastrophizing that are promoted by exposure to ALEs. These results highlight several targets for intervention to decrease NA pain risk.

Association between Self-Reported Bruxism, Peripartum Depression and Myogenous Temporomandibular Disorders among Postpartum Women in Turkey

Background/Aim: It is possible to find studies in the literature evaluating the relationship among self-reported bruxism, psychological factors, and myogenous temporomandibular disorder. In addition, the relationship between these issues has not yet been clarified. The objective of this study was to evaluate the association between peripartum depression, self-reported bruxism, and myogenous temporomandibular disorders among postpartum women in Turkey.

Material and Methods: This study included 220 women, whom were asked about their bruxism behaviour during day and during sleep. Besides, all of them assessed with Short-Form Fonseca’s Anamnestic Index for myogenous temporomandibular disorder and the Edinburgh postnatal depression scale for peripartum depression.

Results: The results showed that, self-reported bruxism was observed at a statistically significantly higher rate (94.3%) in peripartum depression group. 86.5% of the patients with self-reported bruxism had myogenous temporomandibular disorder (p<0.001). As a result, 80.0% of the patients with peripartum depression had myogenous temporomandibular disorder (p<0.001).

Conclusions: In conclusion, a significant relationship has been found between peripartum depression and self-reported bruxism, self-reported bruxism and myogenous temporomandibular disorder, and peripartum depression and myogenous temporomandibular disorder. The present study is the first to evaluate the relationship between peripartum depression, self-reported bruxism, and myogenous temporomandibular disorder so it could be considered as a pilot attempt, and further studies using more representative samples are encouraged.

Do "central sensitization" questionnaires reflect measures of nociceptive sensitization or psychological constructs? Protocol for a systematic review

A protocol for a systematic review examining how central sensitisation questionnaires correlate with sensory or psychological measures to clarify the use of “central sensitisation” in clinical contexts.

Introduction:

Central sensitization (CS) was first defined in animal studies to be increased nociceptive responsiveness due to sensitization of neurons in the central nervous system, usually the result of prolonged nociceptive input or a disease state. Recently, the concept of CS has been adopted in clinical assessments of chronic pain, but its diagnosis in humans has expanded to include the enhancement of a wide range of nociceptive, sensory, and emotional responses. Many poorly understood pain disorders are referred to as “central sensitivity syndrome,” a term associated with a broad range of hypervigilant sensory and emotional responses. Diagnosis often involves a review of medical records and an assessment of behaviour, emotional disposition, and overall sensitivity of a patient. Obviously, these assessments are unable to directly capture the responsiveness of nociceptive neurons. The purpose of this review is to ascertain whether self-report questionnaires associated with central sensitization and the diagnosis of central sensitivity syndrome are associated with enhanced nociceptive responses or whether they more validly measure sensitivity in a broader sense (ie, including emotional responses).

Methods:

Following the PRISMA guidelines, a detailed search of studies that involve the Central Sensitization Inventory or Pain Sensitivity Questionnaire correlated with either nociceptive sensory tests (quantitative sensory testing) or emotional hypervigilance (anxiety, depression, stress, etc) will be conducted on MEDLINE, PsychINFO, and Web of Science.

Perspective:

The review is expected to synthesize correlations between sensitivity questionnaires and nociceptive or emotional sensitivity to determine whether these questionnaires reflect a broadened understanding of the term “central sensitization.”

Can ultrasonography be used to assess capsular distention in the painful temporomandibular joint?

BACKGROUND

To determine whether capsular distention in the painful temporomandibular joint (TMJ) can be assessed by ultrasonography, we compared the capsular width between painful TMJs and painless TMJ. The risk factors for TMJ pain were also investigated including capsular width and other clinical factors such as TMJ sounds that may affect the occurrence and persistence of TMJ pain.

METHODS

TMJ ultrasonography was performed on 87 temporomandibular disorder (TMD) patients, including 47 unilateral and 29 bilateral TMJ pain patients, and 11 patients without TMJ pain.

RESULTS

The capsular width was greater in the 105 painful joints than in the 69 painless joints. Considering individual anatomical variations, the differences between painful and painless joints in unilateral TMJ pain patients were also analyzed, revealing a greater width in painful joints. Capsular width was a risk factor for TMJ pain with an adjusted odds ratio of 1.496 (95% confidence interval 1.312-1.706; p < 0.001) and was significantly correlated with pain scores.

CONCLUSION

This correlation may suggest that pain intensity is associated with widened capsular width because of joint effusion or synovitis. Further studies are required to refine and establish the protocols for standard examinations using ultrasound imaging.

Low-grade inflammation as a potential mediator between depressive symptoms and temporomandibular pain: an 11-year follow-up study on Finnish adults

BACKGROUND

Low-grade inflammation and depressiveness have been associated with chronic pain conditions.

OBJECTIVE

To examine whether low-grade inflammation mediates the association between depressive symptoms and temporomandibular (TM) pain in Finnish adults based on the Health 2000/2011 Surveys (BRIF8901).

METHODS

The sample comprised subjects who underwent clinical TM pain examination (pain on palpation of the masticatory muscles and temporomandibular joints) in 2000 and 2011 and responded to questions on TM pain symptoms in 2011. The serum level of hs-CRP was obtained in both years, and depressiveness was assessed using the Beck Depression Inventory-21 (BDI-21) in 2000 and BDI-13 in 2011. Four subgroups were formed based on the presence of TM pain: No pain, pain in 2000-only, pain in the 2011-only, and pain in both-years. Analyses included Rao Scott's chi-square test cross-sectionally, and multinomial logistic regression longitudinally with the level of hs-CRP and BDI-21 score in 2000 as predictors. Mediation was tested using Hayes A. Processv3.5.

RESULTS

Higher BDI-21/-13 and hs-CRP levels corresponded to higher prevalences of TM pain in both years. Longitudinally, in men, higher hs-CRP level predicted TM pain in 2000-only and TM pain in both-years. Higher BDI-21 score predicted having TM pain in 2011-only. In women, higher BDI-21 score predicted TM pain in 2000-only and having TM pain in both-years. Both BDI-21 and hs-CRP had a direct effect on TM pain outcome with no mediation detected.

CONCLUSION

While depressiveness may increase the risk of chronic TM pain in women, the risk in men is increased by low-grade inflammation.

Comparison of Axis II psychosocial assessment methods of RDC/TMD and DC/TMD as part of DC/TMD-FIN phase II validation studies in tertiary care Finnish TMD pain patients

BACKGROUND

The Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) and Diagnostic Criteria for TMD (DC/TMD) include Axis II instruments for psychosocial assessment.

OBJECTIVES

The aims were to compare the Finnish versions of Axis II psychosocial assessment methods of the RDC/TMD and DC/TMD and to study their internal reliability.

METHODS

The sample comprised 197 tertiary care referral TMD pain patients. The associations between RDC/TMD [Graded Chronic Pain Scale (GCPS) 1.0, Symptom Check List 90-revised (SCL-90R)] and DC/TMD (GCPS 2.0, Patient Health Questionnaire-9 (PHQ-9), PHQ-15) assessment instruments were evaluated using Spearman correlation coefficients, Wilcoxon Signed Rank s, chi-squared test and gamma statistics. The internal reliability and internal inter-item consistency of SCL-90-R, PHQ-9, PHQ-15 and Generalized Anxiety Disorder-7 (GAD-7) were evaluated using Cronbach's alpha coefficient values.

RESULTS

The DC/TMD and RDC/TMD Axis II psychosocial instruments correlated strongly (p < .001). GCPS 1.0 and GCPS 2.0 grades were similarly distributed based on both criteria. The RDC/TMD psychological instruments had a higher tendency to subclassify patients with more severe symptoms of depression and non-specific physical symptoms compared to DC/TMD. The internal reliability and internal inter-item consistency were high for the psychological assessment instruments.

CONCLUSION

The Finnish versions of the RDC/TMD and DC/TMD Axis II psychosocial instruments correlated strongly among tertiary care TMD pain patients. Furthermore, the Axis II psychological assessment instruments indicated high validity and internal inter-item consistency and are applicable in Finnish TMD pain patients as part of other comprehensive specialist level assessments, but further psychometric and cut-off evaluations are still needed.

Association of sleep quality and psychological aspects with reports of bruxism and TMD in Brazilian dentists during the COVID-19 pandemic

BACKGROUND

Dentists are exposed to contamination by SARS-CoV-2 due to dental interventions, leading to a state of alert and potential risk of negative impact in mental health and sleep quality, associated with Temporomandibular Disorder (TMD) and bruxism.

OBJECTIVE

to evaluate the psychosocial status, sleep quality, symptoms of TMD, and bruxism in Brazilian dentists (DSs) during the COVID-19 pandemic.

METHODOLOGY

The sample (n=641 DSs) was divided into three groups (quarantined DSs; DSs in outpatient care; and frontline professionals), which answered an electronic form containing the TMD Pain Screening Questionnaire (Diagnostic Criteria for Temporomandibular Disorders - DC/TMD), the Pittsburgh Sleep Quality Index (PSQI), the Depression, Anxiety and Stress Scale (DASS-21), and the sleep and awake bruxism questionnaire. ANOVA test and Mann Whitney post-test were used, with Bonferroni adjustment (p<0.016) and a 95% confidence level.

RESULTS

Probable TMD was found in 24.3% (n=156) of the participants, while possible sleep and awake bruxism were diagnosed in 58% (n=372) and 53.8% (n=345) of them, respectively. Among all variables evaluated, only symptoms of depression were significantly greater in the quarantined DSs group when compared to those who were working at the clinical care (p=0.002). Working DSs were significantly less likely (OR=0.630, p=0.001) to have depressive symptoms. Those who were not worried or less worried about the pandemic were less likely to experience stress (OR=0.360), anxiety (OR=0.255), and poor sleep quality (OR=0.256). Sleep had a strong positive and moderate correlation with psychological factors on frontline workers and DSs in outpatient care, respectively.

CONCLUSION

The results suggest confinement may have a more negative impact on the life of DSs than the act of being actively working. The concern about Covid-19 and poor sleep quality was significantly prevalent and may negatively affect the quality of life of DSs. Thus, further research on the topic is needed.

Chairside risk assessment for first-onset temporomandibular disorders: Result from the Orofacial Pain: Prospective Evaluation and Risk Assessment data set

BACKGROUND

Temporomandibular disorders (TMD) risk assessment is difficult in general dentistry owing to the complexity of multifactorial risk contributions and the lack of standardized education. The authors explored a health history-based chairside risk assessment.

METHODS

Secondary data analysis was performed on the Orofacial Pain: Prospective Evaluation and Risk Assessment data set. Potential demographic, systemic, and local risk contributors were conceptualized into 10 risk categories. Multivariate Cox proportional hazards modeling with backward selection was applied. Variables with P values < .05 were kept in each successive model.

RESULTS

The analysis included data from 2,737 participants. The final model indicated that people with any psychological conditions, pain disorders, sleep disorders, or orofacial symptoms were at elevated risks of developing first-onset TMD. Results of post hoc analysis showed the coexistence of conditions from multiple body systems conferred greater risk of developing TMD.

CONCLUSIONS

Coexisting conditions and symptoms from multiple body systems substantially increase the risk of developing TMD pain. Therefore, multisystem risk assessment and interprofessional collaborations are important for the prevention of TMD.

PRACTICAL IMPLICATIONS

Dentists should include psychological conditions, pain disorders, sleep disorders, and orofacial symptoms when assessing patients' risk of developing TMD pain.

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.

Modulatory effects of repeated psychophysical stress on masseter muscle nociception in the nucleus raphe magnus of rats

Psychophysical stress can cause neural changes that increase nociception in the orofacial region, particularly the masseter muscle (MM). The nucleus raphe magnus (NRM), which is located in the brain stem, serves the crucial role of regulating nociception through descending modulatory pain control. However, it remains unclear if neural activities in the NRM are affected under psychophysical stress conditions. This study conducted experiments to assess (1) whether neural activity, indicated by Fos expression in an NRM that has experienced MM injury, is affected by the stress of repeated forced swim tests (FST); and (2) whether the selective serotonin reuptake inhibitor fluoxetine administered daily after an FST could affect the number of Fos-positive neurons in the NRM. Results revealed that the stress from repeated FSTs significantly increased the number of Fos-positive neurons in an NRM that had been affected by MM injury. Fluoxetine inhibited increases in the number of Fos-positive neurons in the NRM that occurred as a result of FSTs, but this was not observed in sham rats. These findings indicate that the stress from FSTs could increase nociceptive neural activity in an NRM that has experienced MM injury. This could be due, in part, to changes in serotonergic mechanisms.

Pain-related anxiety promotes pronociceptive processes in Native Americans: bootstrapped mediation analyses from the Oklahoma Study of Native American Pain Risk

INTRODUCTION

Evidence suggests Native Americans (NAs) experience higher rates of chronic pain than the general US population, but the mechanisms contributing to this disparity are poorly understood. Recently, we conducted a study of healthy, pain-free NAs (n = 155), and non-Hispanic whites (NHWs, n = 150) to address this issue and found little evidence that NAs and NHWs differ in pain processing (assessed from multiple quantitative sensory tests). However, NAs reported higher levels of pain-related anxiety during many of the tasks.

OBJECTIVE

The current study is a secondary analysis of those data to examine whether pain-related anxiety could promote pronociceptive processes in NAs to put them at chronic pain risk.

METHODS

Bootstrapped indirect effect tests were conducted to examine whether pain-related anxiety mediated the relationships between race (NHW vs NA) and measures of pain tolerance (electric, heat, ischemia, and cold pressor), temporal summation of pain and the nociceptive flexion reflex (NFR), and conditioned pain modulation of pain/NFR.

RESULTS

Pain-related anxiety mediated the relationships between NA race and pain tolerance and conditioned pain modulation of NFR. Exploratory analyses failed to show that race moderated relationships between pain-related anxiety and pain outcomes.

CONCLUSION

These findings imply that pain-related anxiety is not a unique mechanism of pain risk for NAs, but that the greater tendency to experience pain-related anxiety by NAs impairs their ability to engage descending inhibition of spinal nociception and decreases their pain tolerance (more so than NHWs). Thus, pain-related anxiety may promote pronociceptive processes in NAs to place them at risk for future chronic pain.

µ-Opioid Activity in Chronic TMD Pain Is Associated with COMT Polymorphism

Clinicians have the dilemma of prescribing opioid or nonopioid analgesics to chronic pain patients; however, the impact of pain on our endogenous µ-opioid system and how our genetic profile (specifically catechol-O-methyltransferase [COMT] polymorphisms) impacts its activation are currently unknown. Twelve chronic temporomandibular disorder (TMD) patients and 12 healthy controls (HCs) were scanned using positron emission tomography (PET) with [11C]carfentanil, a selective radioligand for µ-opioid receptors (µORs). The first 45 min of each PET measured the µOR nondisplaceable binding potential (BPND) at resting state, and the last 45 min consisted of a 20-min masseteric pain challenge with an injection of 5% hypertonic saline. Participants were also genotyped for different COMT alleles. There were no group differences in µOR BPND at resting state (early phase). However, during the masseteric pain challenge (late phase), TMD patients exhibited significant reductions in µOR BPND (decreased [11C]carfentanil binding) in the contralateral parahippocampus (P = 0.002) compared to HCs. The µOR BPND was also significantly lower in TMD patients with longer pain chronicity (P < 0.001). When considering COMT genotype and chronic pain suffering, TMD patients with the COMT158Met substitution had higher pain sensitivity and longer pain chronicity with a 5-y threshold for µOR BPND changes to occur in the parahippocampus. Together, the TMD diagnosis, COMT158Met substitution, and pain chronicity explained 52% of µOR BPND variance in the parahippocampus (cumulative R2 = 52%, P < 0.003, and HC vs. TMD Cohen's effect size d = 1.33 SD). There is strong evidence of dysregulation of our main analgesic and limbic systems in chronic TMD pain. The data also support precision medicine by helping identify TMD patients who may be more susceptible to chronic pain sensitivity and opioid dysfunction based on their genetic profile.

Follow-up results of a randomized clinical trial for low-level laser therapy in painful TMD of muscular origins

Objective: To characterize short- and long-term assessment of the low-intensity laser therapy (LLLT) effectiveness in women with TMD of muscular origins and to evaluate whether the information about the treatment received (active or placebo) modifies the pain intensity.Methods: Forty-one women with painful TMD (31.7 ± 5.2 years) were divided into laser (n = 20) and placebo (n = 21) groups. The pain intensity was measured at the baseline, after the LLLT (T8), 6 and 12 months. At the 6-month follow-up, the groups received information about the active or placebo treatment.Results: At T8 and 6-month, both active and placebo LLLT were effective in reducing pain (p < .05). After one year, the groups showed similar pain. Active LLLT was more effective in reducing pain palpation (p = .001) and referred pain (p = .04) in the region of the TMJs. The information about the treatment modified the perceived pain intensity.Conclusion: Active and placebo LLLT are effective for painful TMD of muscular origins in the short-term. Information about the treatment impairs the subjective perception of pain.

Premorbid and concurrent predictors of TMD onset and persistence

BACKGROUND

Multiple risk factors predict temporomandibular disorders (TMD) onset, but temporal changes in risk factors and their contribution to risk of TMD have not been evaluated. The study aims were to (a) describe changes occurring in premorbid TMD risk factors when re-measured at TMD onset and 6 months later, and (b) determine if measures of change improve accuracy in predicting TMD incidence compared to premorbid measures alone.

METHODS

In this observational prospective cohort study at four university research clinics, 3,258 community-based, 18- to 44-year-olds without TMD were enrolled. During the 3-year median follow-up, 260 incident cases of first-onset TMD were identified, and 196 TMD-free subjects were selected as matched controls. Six-months later, 147 of 260 incident cases (56.6%) were re-examined revealing 72 (49%) with 'persistent TMD' and 75 (51%) whose condition had resolved ('transient TMD'). Virtually all (126) of the 127 re-examined controls remained without TMD. Questionnaires and clinical measurements evaluated risk factors from clinical, health, psychological and behavioural and neurosensory domains.

RESULTS

Most risk factors across all four domains increased with TMD onset, remained elevated in the persistent group and declined in the transient group (i.e., significant ANOVA interactions, p < .05). Accuracy in predicting first-onset TMD, quantified as area under the receiver operating characteristic curve was 0.71 (95% CL 0.68, 0.73) using only premorbid measures of risk factors, which increased to 0.91 (95% CL 0.89, 0.94) after addition of change measures.

CONCLUSIONS

TMD pain onset and persistence appear to be determined by enduring characteristics of the person as well as mutually interactive with temporally evolving variables.

SIGNIFICANCE

TMD is known to be a complex disorder, in which onset and persistence are associated with disease-related variables in multiple domains, including environmental exposure, clinical, psychological, health status, and pain processing variables. Using a more dynamic approach in order to capture change across time, many aspects of those domains were found to worsen prior to the reporting of pain, with bidirectional influences between domains and pain emergence likely. TMD onset appears to represent the cumulative effect of multiple system dysregulation.

Sensory, Affective, and Catastrophizing Reactions to Multiple Stimulus Modalities: Results from the Oklahoma Study of Native American Pain Risk

Native Americans (NAs) have a higher prevalence of chronic pain than any other U.S. racial/ethnic group; however, little is known about the mechanisms for this pain disparity. This study used quantitative sensory testing to assess pain experience in healthy, pain-free adults (n = 137 NAs (87 female), n = 145 non-Hispanic whites (NHW; 68 female)) after painful electric, heat, cold, ischemic, and pressure stimuli. After each stimulus, ratings of pain intensity, sensory pain, affective pain, pain-related anxiety, and situation-specific pain catastrophizing were assessed. The results suggested that NAs reported greater sensory pain in response to suprathreshold electric and heat stimuli, greater pain-related anxiety to heat and ischemic stimuli, and more catastrophic thoughts in response to electric and heat stimuli. Sex differences were also noted; however, with the exception of catastrophic thoughts to cold, these finding were not moderated by race/ethnicity. Together, findings suggest NAs experience heightened sensory, anxiety, and catastrophizing reactions to painful stimuli. This could place NAs at risk for future chronic pain and could ultimately lead to a vicious cycle that maintains pain (eg, pain → anxiety/catastrophizing → pain). PERSPECTIVE: NAs experienced heightened sensory, anxiety, and catastrophizing reactions in response to multiple pain stimuli. Given the potential for anxiety and catastrophic thoughts to amplify pain, this characteristic may place them at risk for pain disorders and could lead to a vicious cycle that maintains pain.

Preclinical Signs of a Temporomandibular Disorder in Female Patients With Episodic Cervicogenic Headache Versus Asymptomatic Controls: A Cross-Sectional Study

BACKGROUND

The International Classification of Headache Disorders, 3rd Edition, accepted "headache attributed to temporomandibular disorders" as a valid headache. The neurophysiologic interplay between cervical structures and the temporomandibular joint, however, might also suggest that a temporomandibular disorder could develop in patients with cervicogenic headache.

OBJECTIVE

To compare the presence of preclinical temporomandibular signs between female patients with episodic cervicogenic headache and a control group.

DESIGN

Case-controlled cross-sectional design.

SETTING

Institutional setting: Hasselt University.

PARTICIPANTS

Twenty-two women (mean age ± SD: 20.7 ± 2.5 years) with episodic cervicogenic headache, without temporomandibular signs and 22 matched (gender, age, level of education, occupation) asymptomatic controls (21 ± 2.3 years).

METHODS

(Un)assisted temporomandibular range of motion, pressure pain thresholds, painful palpations were examined and the level of perceived stress was measured.

MAIN OUTCOME MEASUREMENTS

Temporomandibular range of motion (mm), pressure pain thresholds (kPa/cm²), painful palpations (yes/no), and level of perceived stress (Perceived Stress Scale).

RESULTS

Maximal mouth-opening was significantly smaller in the headache group (P <.05; effect size [ES] -0.45). Palpation of the masseter resulted in significantly more positive pain responses in the headache group at the left (P = .009; ES ∞) and right (P = .002;ES 17.5) origin, left (P = .004; ES 14.54) and right (P = .03; ES 5.71) body and left (P < .001; ES 12) insertion. Significantly lower pressure pain thresholds on the left and right anterior (P = .03; ES -0.33 resp. P = .02; ES -0.35), central (P = .003; ES 1.02 resp. P = .02; ES 0.79) and right posterior (P = .03; ES 0.62) temporalis and right tibialis anterior (P = .03; ES -0.33) were measured in the headache group. The level of perceived stress was significantly higher (P = .02) in the headache group.

CONCLUSIONS

Patients with episodic cervicogenic headache present with signs of a preclinical temporomandibular disorder and sensitization. The smaller range of motion, lower pressure pain thresholds, and higher levels of stress accentuate the multidimensionality of the problem.

LEVEL OF EVIDENCE

IV.

Exodontia-induced muscular hypofunction by itself or associated to chronic stress impairs masseter muscle morphology and its mitochondrial function

Stress is associated with orofacial pain sensitivity and is qualified as a temporomandibular disorder risk factor. During stressful periods, painful thresholds of masticatory muscles in individuals suffering muscle facial pain are significantly lower than in controls, but the exact physiologic mechanism underlying this relation remains unclear. Our hypothesis is that chronic unpredictable stress and masticatory hypofunction induce morphologic and metabolic masseter muscle changes in rats. For test this hypothesis, adult Wistar rats were submitted to chronic unpredictable stress and/or exodontia of left molars and the left masseter muscle was removed for analysis. The parameters evaluated included ultrastructure, oxidative level, metabolism activity and morphological analysis in this muscle. Our data show by histological analysis, that stress and exodontia promoted a variation on diameters and also angled contours in masseter fibers. The masticatory hypofunction increased oxidative metabolism as well as decreased reactive species of oxygen in masseter muscle. The ultrastructural analysis of muscle fibers showed disruption of the sarcoplasmic reticulum cisterns in certain regions of the fiber in stress group, and the disappearance of the sarcoplasmic reticulum membrane in group with association of stress and exodontia. Our findings clarify mechanisms by which chronic stress and masticatory hypofunction might be involved in the pathophysiology of muscular dysfunctions. Masticatory hypofunction influenced oxidative stress and induced oxidative metabolism on masseter muscle, as well as altered its fiber morphology. Chronic stress presented malefic effect on masseter morphology at micro and ultra structurally. When both stimuli were applied, there were atrophic fibers and a complete mitochondrial derangement.

Associations between symptoms of temporomandibular disorders, quality of life and psychological states in Asian Military Personnel

BACKGROUND

Symptoms of Temporomandibular Disorders (TMD) could affect oral health-related quality of life (OHRQoL) and psychological distress.

OBJECTIVE

This study aims to determine the prevalence of TMD symptoms, and impact of type and number of TMD symptoms on OHRQoL and psychological states among Asian military personnel.

METHOD

The study was conducted across 12 military dental centres using self-administered questionnaire comprising demographical data, DC/TMD symptom questionnaire, OHIP-14 and DASS-21. A total of 3028 personnel, aged between 18-65 years old, were invited to participate with an acceptance rate of 90.5%. Data analysis was done using non-parametric tests, regression analysis and Spearman correlation (P < 0.05).

RESULTS

Out of 2043 subjects (1998 males; 45 females, mean age 24.18 ± 7.18 years), 36.32% (n = 742) reported at least one TMD symptom. Significant differences in summary OHIP-14, depression, anxiety and stress scores were observed between subjects with and without TMD symptoms. Significant differences in OHIP-14 and DASS-21 scores were observed between dissimilar type and number of TMD symptoms in the TMD group. Those with headaches and 2-3 symptoms have substantially poorer OHRQoL and greater psychological distress. Associations between number of TMD symptoms, quality of life, depression, anxiety and stress were significant but weak (r = 0.19-0.40).

CONCLUSIONS

Symptoms of Temporomandibular Disorders were prevalent among Asian military population. Significant differences in OHRQoL and psychological states were observed between subjects with and without TMD symptoms. Specific type and number of TMD symptoms impacted OHRQoL and psychological states differently. Associations between number of TMD symptoms and quality of life, depression, anxiety and stress were significant but weak.

The associations between work-related factors and temporomandibular disorders among female full-time employees: findings from the Fourth Korea National Health and Nutrition Examination Survey IV (2007-2009)

Background

The aim of this study was to investigate the association between work-related factors and temporomandibular disorders (TMD) among female full-time employees using representative data from a national population-based survey.

Methods

Data from the Fourth Korea National Health and Nutrition Examination Survey IV (2007–2009) were used to analyze 1,612 women. Complex samples logistic regression was applied for adjusting for general characteristics and work-related factors to examine the association between work-related factors and TMD.

Results

The prevalence of TMD was 12.8% in this study population. With respect to age, educational status, marital status, problem drinking, exercise, and stress, there were statistically significant differences in the prevalence of TMD. In logistic regression analyses on complex samples, based on 40 h or less per week, odds ratios (ORs) for respondents who worked 40–48 working hours, 49–60 working hours, and more than 60 h were 1.16 (95% confidence interval (CI) 0.69–1.94), 1.41 (95% CI 0.79–2.54), and 2.43 (95% CI 1.29–4.59), after adjusting for general characteristics, working schedule, employment status, and occupation.

Conclusions

This study found that long working hours were significantly associated with TMD in Korean female full-time employees.

Inhibitory effects of fluoxetine, an antidepressant drug, on masseter muscle nociception at the trigeminal subnucleus caudalis and upper cervical spinal cord regions in a rat model of psychophysical stress

This study aimed to determine whether psychophysical stress conditionings had facilitatory effects on masseter muscle nociception in the central nervous system via serotonergic mechanisms in rats. Two experiments were conducted to assess: (1) whether repeated forced swim stress for 3 days increased the number of Fos-positive neurons evoked by masseter muscle injury due to formalin injection; and (2) whether serotonin-reuptake inhibitor, fluoxetine, administered daily after each stress conditioning, had modulatory roles on Fos expression. The number of Fos-positive cells was quantified in several areas within the trigeminal subnucleus caudalis (Vc) and upper cervical spinal cord regions (Vc areas), including the ventrolateral area of the trigeminal subnucleus interpolaris/Vc transition, and the middle or caudal portion of the Vc regions, since nociceptive neural activity in the Vc region could play critical roles in deep craniofacial nociception. We found that forced swim stress conditionings increased depression-like behaviors, which was prevented by fluoxetine. Repeated forced swim stress significantly increased Fos expression in all Vc areas compared with those of non-stressed rats, while systemic administration of fluoxetine significantly decreased Fos expression in all areas, but mainly in the caudal Vc region, in stressed rats. Fluoxetine had no effect on Fos expression in non-stressed rats. These results indicate that repeated forced swim stress conditionings increase Fos expression in the Vc areas, and the contribution of serotonergic mechanisms to masseter muscle nociception could be greater in stressed rats than in sham rats. These results support the hypothesis that changes in brain function, including serotonergic mechanisms, in the Vc areas play critical roles in enhanced masseter muscle nociceptive responses under psychophysical stress conditions.

Pain catastrophizing is associated with poorer health-related quality of life in pediatric patients with sickle cell disease

Background

Sickle cell disease (SCD) is an inherited disorder of the red blood cells and is associated with chronic multisystem involvement. While SCD has been associated with poorer health-related quality of life (HRQoL), there is a paucity of data on the relationship of psychological covariates other than anxiety and depression and quality of life (QoL) in children with SCD.

Materials and methods

We performed a cross-sectional study of psychological factors, HRQoL, and pain-related outcomes in participants with SCD and race-matched controls as part of a larger study of experimental pain phenotyping.

Results

Pain catastrophizing was inversely correlated with HRQoL measured by the PedsQL™ Generic Core Scale in children with SCD, while this was not noted in control participants. Psychological factors, such as anxiety and depressive symptoms, were also associated with poorer HRQoL in both children with SCD and controls. We did not find an association of psychological factors with prior health care utilization. Psychological factors such as anxiety and depressive symptoms were inversely correlated with pain interference, but not pain intensity in SCD.

Conclusion

Catastrophizing is associated with poorer HRQoL in SCD, but in this study, it was not associated with pain intensity or interference and health care utilization in children with SCD. Further studies are needed to fully define the association of psychological factors including catastrophizing with QoL, pain burden, and SCD outcomes.

Benefits of implementing pain-related disability and psychological assessment in dental practice for patients with temporomandibular pain and other oral health conditions

BACKGROUND

Evidence in the field of dentistry has demonstrated the importance of pain-related disability and psychological assessment in the development of chronic symptoms. The Diagnostic Criteria for Temporomandibular Disorders offer a brief assessment for the diagnostic process in patients with orofacial pain (Axis II). The authors describe relevant outcomes that may guide general oral health care practitioners toward tailored treatment decisions and improved treatment outcomes and provide recommendations for the primary care setting.

METHODS

The authors conducted a review of the literature to provide an overview of knowledge about Axis II assessment relevant for the general oral health care practitioner.

RESULTS

The authors propose 3 domains of the Axis II assessment to be used in general oral health care: pain location (pain drawing), pain intensity and related disability (Graded Chronic Pain Scale [GCPS]), and psychological distress (Patient Health Questionnaire-4 [PHQ-4]). In the case of localized pain, low GCPS scores (0-II), and low PHQ-4 scores (0-5), patients preferably receive treatment in primary care. In the case of widespread pain, high GCPS scores (III-IV), and high PHQ-4 scores (6-12), the authors recommend referral to a multidisciplinary team, especially for patients with temporomandibular disorder (TMD) pain.

CONCLUSIONS

The authors recommend psychological assessment at first intake of a new adult patient or for patients with persistent TMD pain. The authors recommend the pain-related disability screening tools for all TMD pain symptoms and for dental pain symptoms that persist beyond the normal healing period.

PRACTICAL IMPLICATIONS

A brief psychological and pain-related disability assessment for patients in primary care may help the general oral health care practitioner make tailored treatment decisions.

Overlapping Chronic Pain Conditions: Implications for Diagnosis and Classification

There is increasing recognition that many if not most common chronic pain conditions are heterogeneous with a high degree of overlap or coprevalence of other common pain conditions along with influences from biopsychosocial factors. At present, very little attention is given to the high degree of overlap of many common pain conditions when recruiting for clinical trials. As such, many if not most patients enrolled into clinical studies are not representative of most chronic pain patients. The failure to account for the heterogeneous and overlapping nature of most common pain conditions may result in treatment responses of small effect size when these treatments are administered to patients with chronic overlapping pain conditions (COPCs) represented in the general population. In this brief review we describe the concept of COPCs and the putative mechanisms underlying COPCs. Finally, we present a series of recommendations that will advance our understanding of COPCs.

PERSPECTIVE

This brief review describes the concept of COPCs. A mechanism-based heuristic model is presented and current knowledge and evidence for COPCs are presented. Finally, a set of recommendations is provided to advance our understanding of COPCs.

VEGF promotes cartilage angiogenesis by phospho-ERK1/2 activation of Dll4 signaling in temporomandibular joint osteoarthritis caused by chronic sleep disturbance in Wistar rats

Chronic sleep disturbance (CSD) has been linked to the development of temporomandibular joint osteoarthritis (TMJ-OA). While the pathogenesis of TMJ-OA is unclear, recent studies indicate that osteochondral angiogenesis is important. We developed a rat model of CSD induced TMJ-OA to investigate the changes caused by sleep disturbance and to correlate them with vascular invasion in the TMJ. We found pathological alterations and an increased microvessel density in the rat TMJ following CSD. VEGF, Dll4 and p-ERK1/2, the expression of angiogenic factors, were highly expressed in the rat mandibular condylar cartilage and their expression increased with CSD. Furthermore, we show that VEGF-induce activation of ERK1/2, which in turn, increases Dll4 expression. Together, our results suggest that CSD can cause OA-like pathological alterations in the rat TMJ by increasing angiogenesis.

The IL-1Ra gene variable number tandem repeat variant is associated with susceptibility to temporomandibular disorders in Turkish population

BACKGROUND

Temporomandibular joint disorders (TMD) are a group of disorders involving temporomandibular joint and related structures. Interleukine-1 receptor antagonist (IL-1Ra) is an important anti-inflammatory molecule that competes with other interleukin-1 molecules. This study was designed to investigate the possible association of the IL-1Ra VNTR variant with the risk of TMD in the Turkish population.

METHODS

Peripheral blood samples were collected from 100 patients with TMD (23 males, 77 females) and 110 healthy individuals (35 males, 75 females). Genotyping of IL-1Ra 86 bp VNTR variant was evaluated by gel electrophoresis after polymerase chain reaction (PCR).

RESULTS

Our results show that there is a statistically significant difference between TMD patients and control group with respect to IL-1Ra genotype distribution and allele frequencies. 1.2, 1.4, and 4.4 genotypes were more common in patients, while 2.2 and 3.3 genotypes were rarer (P<.000). Frequency of alleles 1 and 4 was higher in patient groups (P<.000), whereas alleles 2 and 3 had a lower frequency in patients with TMD (P<.000).

CONCLUSIONS

This is the first correlation study that evaluates the association between IL-1Ra gene VNTR variant and TMD. The VNTR variant related to IL-1Ra gene showed a strong pattern of association with TMD that may have a potential impact on disease counseling and management. Larger studies with various ethnicities are needed to establish the impact of IL-1Ra VNTR variant on risk of developing TMD.