Association between sleep bruxism and temporomandibular disorders: a polysomnographic pilot study

Effects of bruxism on temporomandibular joint internal derangement in patients with unilateral temporomandibular joint pain: The role of magnetic resonance imaging diagnostics

OBJECTIVE

This study compared temporomandibular joint (TMJ) magnetic resonance imaging (MRI) findings between bruxism and control groups with unilateral TMJ pain as well as the TMJ MRI findings for the painful and non-painful sides of individuals in the two groups.

METHODS

Clinical and MRI findings of patients seen at Uşak University, Dentistry Faculty, Department of Oral and Maxillofacial Surgery for unilateral TMJ pain between 2017 and 2020 were analyzed. Bruxism was diagnosed based on clinical findings and patient history. The MRI variables were disc/condyle relationship (normal, disc displacement with reduction, or disc displacement without reduction), disc structure (normal and abnormal), condyle degeneration type (normal, moderate, or severe), and joint effusion (absent or present). Pain was recorded based on a visual analog scale (VAS) numbered between 0 and 10. Statistical analyses were performed using IBM SPSS. The data were distributed non-normally according to the results of Kolmogorov-Smirnov tests. The Mann-Whitney U test was used to compare age and VAS. Chi-square tests were used to compare categorical variables. Statistical significance was defined as p < 0.05.

RESULTS

This study assessed the MRI records of 558 cases of TMJ pain. No significant differences in disc/condyle relation, disc structure, condyle structure, or effusion were observed between the control and bruxism groups (p > 0.05). However, a significant difference in TMJ MRI findings was observed between the painful and non-painful sides of each individual in the control and bruxism groups (p = 0.001, p < 0.001 and p = 0.004, p < 0.001, respectively).

CONCLUSION

The results of this study established a relationship between the painful side for each patient and TMJ MRI findings. In particular, individuals with bruxism had a higher rate of TMJ internal derangement and effusion on the painful side.

Polysomnographic characteristics of sleep-related bruxism: What are the determinant factors for temporomandibular disorders?

This study aimed to evaluate the clinical and polysomnographic characteristics of sleep bruxism (SB) and delineate the determinant factors for temporomandibular disorders (TMD). Forty-six patients were allocated into the SB group (n = 26) and control group (n = 20). The signs and symptoms of TMD were recorded using the Research Diagnostic Criteria for TMD. Patients underwent a full-night polysomnographic recording and masseter and temporal muscle electromyographic recordings. Clinical and polysomnographic data in patients with SB were analyzed in relation to TMD. The presence of TMJ sounds was significantly correlated with the number of bruxism bursts. Intra-articular pain in the TMJ was neither correlated with clinical nor polysomnographic parameters in patients with SB. Lower sleep efficiency in patients with SB was caused by a higher number of bruxism episodes. Morning headaches were associated with the severity of SB during rapid eye movement sleep.

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.

Sleep bruxism and temporomandibular disorders: A scoping review of the literature

OBJECTIVE

To provide a scoping review of the literature by assessing all the English-language papers that investigated the relationship between sleep bruxism (SB) and temporomandibular disorders (TMDs).

STUDY DATA AND SOURCES

A search was performed in the National Library of Medicine (PubMed) and Scopus databases, in order to identify all the articles published assessing the relationship between SB and TMDs, by several different approaches. The selected articles were then structurally read and summarized in PICO tables. The articles were selected independently by the two authors.

STUDY SELECTION

Out of 185 references that were initially retrieved, 47 articles met the inclusion criteria and were thus included in the review. The studies were divided into four categories based on the type of SB assessment: 1. questionnaire/self-report (n = 26), 2. clinical examination (n = 7), 3. electromyography (EMG) (n = 5), and 4. polysomnography (PSG) (n = 9).

CONCLUSIONS

Studies based on questionnaire/self-report SB featured a low specificity for SB assessment, and in general they found a positive association with TMD pain. On the contrary, instrumental studies (i.e., electromyography, polysomnography) found a lower level of association or even a negative relationship between SB and TMD pain. Findings from this updated review confirmed the conclusions of a previous review by Manfredini & Lobbezoo, suggesting that literature findings on the relationship between SB and TMDs are dependent on the assessment strategies that are adopted for SB. Future studies should consider SB as a multifaceted motor behavior that must be evaluated in its continuum spectrum, rather than using a simplified dichotomous approach of presence/absence.

Bruxism definition: Past, present, and future - What should a prosthodontist know?

STATEMENT OF PROBLEM

The definition of bruxism has evolved, and the dental profession needs to align with the terminologies adopted in the current literature of sleep and orofacial pain medicine.

PURPOSE

The purpose of this review was to discuss the recent evolution of bruxism concepts and the implications for changing the definition that is currently used by the prosthodontic community.

MATERIAL AND METHODS

A historical perspective on the evolution of the definition of bruxism, as well as a systematic literature review on the validity of polysomnography (PSG)-based criteria for sleep bruxism diagnosis to detect the presence of clinical consequences, is presented. Selected articles were read in a structured Population, Intervention, Comparison, Outcome (PICO) format to answer the question "If a target population with conditions such as tooth wear, dental implant complications, and temporomandibular disorders (P) is diagnosed with sleep bruxism by means of PSG (I) and compared with a population of nonbruxers (C), is the occurrence of the condition under investigation (that is, the possible pathologic consequences of sleep bruxism) be different between the 2 groups (O)?"

RESULTS

Eight studies were eligible for the review, 6 of which assessed the relationship between PSG-diagnosed sleep bruxism and temporomandibular disorder pain, while the other 2 articles evaluated the predictive value of tooth wear for ongoing PSG-diagnosed sleep bruxism and the potential role of sleep bruxism in a population of patients with failed dental implants. Findings were contradictory and not supportive of a clear-cut relationship between sleep bruxism assessed based on available PSG criteria and any clinical consequence. The literature providing definitions of bruxism as a motor behavior and not pathology has been discussed.

CONCLUSIONS

The bruxism construct has shifted from pathology to motor activity with possibly even physiological or protective relevance. An expert panel including professionals from different medical fields published 2 consecutive articles focusing on the definition of bruxism, as well as an overview article presenting the ongoing work to prepare a Standardized Tool for the Assessment of Bruxism (STAB) to reflect the current bruxism paradigm shift from pathology to behavior (that is, muscle activity). As such, dental practitioners working in the field of restorative dentistry and prosthodontics are encouraged to appraise this evolution.

Association of self-reported bruxism with temporomandibular disorders - Northern Finland Birth Cohort (NFBC) 1966 study

Objective: To investigate the prevalence of self-reported bruxism and its association with temporomandibular disorders (TMD). The hypothesis of the study was that self-reported bruxism is associated with TMD.Methods: The data were gathered from 1962 subjects who participated in a field study in 2012-2013, including a questionnaire concerning bruxism and TMD symptoms as well as clinical sub-diagnoses of TMD using the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Statistical method was chi-square test. Bonferroni correction was made, and a p-value of <0.003 was considered as significant.Results: The prevalence of self-reported bruxism was 39.6%: 34.0% in men and 44.5% in women. Those who reported sleep bruxism (SB) or awake bruxism (AB) had significantly more pain-related TMD symptoms and signs compared to those not reporting bruxism.Conclusion: The prevalence of self-reported bruxism is high among middle-aged adults and is associated with TMD pain-related symptoms and signs, as well as TMD diagnoses.

Correlations between Sleep Bruxism and Temporomandibular Disorders

The aim of this study was to identify correlations between sleep bruxism (SB) and temporomandibular disorders (TMD) as diagnosed by means of the research diagnostic criteria for temporomandibular disorders (RDC/TMD). Sleep bruxism was diagnosed on the basis of I) validated questionnaires, II) clinical symptoms, and III) electromyographic/electrocardiographic data. A total of 110 subjects were included in the study. Fifty-eight patients were identified as bruxers and 52 as nonbruxers. A psychosocial assessment was also performed. An RDC/TMD group-I diagnosis (myofascial pain) was made for 10 out of 58 bruxers, whereas none of the nonbruxers received a diagnosis of this type. No significant differences were found between bruxers and nonbruxers with regard to RDC/TMD group-II (disc displacement) and group-III (arthralgia, arthritis, arthrosis) diagnoses. Somatization was significantly more common among bruxers than nonbruxers. Multivariate logistic regression analysis revealed that somatization was the only factor significantly correlated with the diagnosis of myofascial pain. The results of this study indicate a correlation between myofascial pain, as diagnosed using the RDC/TMD, and somatization. It seems that somatization is a stronger predictor of an RDC/TMD diagnosis of myofascial pain than sleep bruxism is.

Absence of joint pain identifies high levels of sleep masticatory muscle activity in myofascial temporomandibular disorder

Although the development of reliable diagnostic criteria for temporomandibular disorders (TMDs) has operationalised identification of a subgroup with myofascial pain (mTMD), causal mechanisms remain elusive. This study examines masticatory muscle activity (MMA) in more homogenous research subgroups of mTMD. Data from an existing case-control study of women were used to subcategorise mTMD cases based on joint pain with palpation to isolate muscle-only pain (M-pain) vs muscle and joint pain (MJ-pain). Differences in laboratory indicators of MMA, specifically research diagnostic criteria for sleep bruxism (SB) and high background EMG activity, and other clinical and sociodemographic indicators were examined between groups. Compared to controls, the MJ-pain subgroup did not show elevated background EMG or sleep bruxism. In contrast, the M-pain subgroup showed significantly higher background EMG and a trend towards elevated prevalence of sleep bruxism. These results may explain why it has been difficult for studies of SB in mixed TMD and even mTMD samples to find a consistent positive association, since a positive association may be limited to mTMD without joint pain. The subcategorising of mTMD based on joint pain with palpation (ie M-pain, MJ-pain) appears to reveal subgroups with relatively high and low sleep masticatory muscle-specific activity. Findings need replication in a larger study with updated mTMD diagnostic criteria, but may prove useful for understanding mechanism of pain maintenance in mTMD with and without joint pain.

Oral diseases and oral health related behaviors in adolescents living in Maasai population areas of Tanzania: a cross-sectional study

Background

Oral diseases, such as dental caries, tooth wear, dental erosion and periodontal diseases are major health problems in many societies. The study aim was to explore the association between oral health related behaviors and the presence of oral diseases in adolescents living in Maasai population areas in the northern part of Tanzania.

Methods

A cross sectional study was conducted in 2016 using one stage cluster sample design. A total of 989 adolescents were invited and 906 (91.6%; (Maasais n = 721, non Maasais n = 185) accepted the invitation and completed an interview and clinical oral examination in a school setting (mean age 13.4 years, SD 1.2, range 12–17 years). Chi-square test, bivariate analysis and logistic regression were performed to analyze data.

Results

Logistic regression revealed that: adolescents with low frequency of tooth cleaning (OR = 10.0, CI 4.3–20.0) was associated with poor oral hygiene and that more regular tooth cleaning (OR = 0.1, CI 0.04–0.14) and the use of plastic type of tooth brush (OR = 0.7, CI 0.53–0.99) were associated with less gingival bleeding. High consumption of biscuits (OR = 2.5, CI 1.7–3.8) was associated with presence of dental caries and the use of magadi (OR = 24.2, CI 11.6–50.6) as a food additive was the covariate for more severe dental fluorosis (TF grade 5–9). Regular intake of carbonated soft drinks (OR = 1.6, CI 1.1–2.5) and regular tooth cleaning (OR = 1.7, CI 1.1–2.6) were independently associated with dental erosion. Using teeth as a tool for: biting nails (OR = 1.9, CI 1.4–2.4), opening soda (OR = 1.8, CI 1.4–2.4) and holding needles (OR = 1.6, CI 1.3–2.1) were covariates for tooth wear. Adolescents who reported to clench/grind their teeth (OR = 2.3, CI 1.5–3.7) was the only covariate for TMD. In several of the investigated factors, there were significant differences between the Maasai and non Maasai ethnic groups.

Conclusion

Oral health related behaviors have a significant impact on oral diseases/conditions among adolescents attending primary schools in Maasai population areas with obvious differences in behavior between the Maasai and non Maasai ethnic groups. There is a need for addressing oral health and to encourage behaviors that promote good oral health and dental care service utilization in this society.

Sleep and awake bruxism in adults and its relationship with temporomandibular disorders: A systematic review from 2003 to 2014

OBJECTIVE

In order to establish a relationship between bruxism and temporomandibular disorders (TMDs), a systematic review was performed.

MATERIALS AND METHODS

A systematic research was performed based on PubMed, Cochrane Library, Medline, Embase, BIREME, Lilacs and Scielo data bases, between 2003 and 2014 including all languages. Descriptive clinical cases were identified. Two independent authors selected the articles. PICO format was used to analyse the studies and the Newcastle-Ottawa Scale (NOS) was used to verify the quality of the evidence.

RESULTS

Thirty-nine studies (n = 39) were analysed in this review. According to bruxism diagnosis, articles were grouped as follows: polysomnographic diagnosis (PSG) (n = 7), clinical diagnosis (n = 11) and survey/self-report (n = 21). Thirty-three articles (n = 33) established a positive relation between bruxism and TMD and six (n = 6) did not. Quality of evidence was low to moderate. In general, the most part of the studies showed shortcomings on their design with bias risk, and also had a low sensitivity on bruxism diagnosis.

CONCLUSIONS

The evidence based on PSG was not as conclusive as the studies that used surveys and clinical exam to diagnosis bruxism, when bruxism was related to TMD. Sleep bruxism could be associated with myofascial pain, arthralgia and joint pathology as disc displacement and joint noises. Although the evidence at present is inconclusive and does not provide information according to the type of bruxism (bruxism sleep and wakefulness), it is possible to suggest that bruxism would be associated with TMD.

Is bruxism a disorder or a behaviour? Rethinking the international consensus on defining and grading of bruxism

Inspired by the international consensus on defining and grading of bruxism (Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ et al. J Oral Rehabil. 2013;40:2), this commentary examines its contribution and underlying assumptions for defining sleep bruxism (SB). The consensus' parsimonious redefinition of bruxism as a behaviour is an advance, but we explore an implied question: might SB be more than behaviour? Behaviours do not inherently require clinical treatment, making the consensus-proposed 'diagnostic grading system' inappropriate. However, diagnostic grading might be useful, if SB were considered a disorder. Therefore, to fully appreciate the contribution of the consensus statement, we first consider standards and evidence for determining whether SB is a disorder characterised by harmful dysfunction or a risk factor increasing probability of a disorder. Second, the strengths and weaknesses of the consensus statement's proposed 'diagnostic grading system' are examined. The strongest evidence-to-date does not support SB as disorder as implied by 'diagnosis'. Behaviour alone is not diagnosed; disorders are. Considered even as a grading system of behaviour, the proposed system is weakened by poor sensitivity of self-report for direct polysomnographic (PSG)-classified SB and poor associations between clinical judgments of SB and portable PSG; reliance on dichotomised reports; and failure to consider SB behaviour on a continuum, measurable and definable through valid behavioural observation. To date, evidence for validity of self-report or clinician report in placing SB behaviour on a continuum is lacking, raising concerns about their potential utility in any bruxism behavioural grading system, and handicapping future study of whether SB may be a useful risk factor for, or itself a disorder requiring treatment.

Can palpation-induced muscle pain pattern contribute to the differential diagnosis among temporomandibular disorders, primary headaches phenotypes and possible bruxism?

BACKGROUND

The evaluation of possible differences in the distribution or characteristics of palpation-induced pain in the masticatory muscles could be valuable in terms of diagnostic assessment. The aim of this study was to evaluate the impact of different combinations of anterior temporalis (AT) and masseter palpation-induced pain in the diagnostic of temporomandibular disorder (TMD), primary headaches and bruxism.

MATERIAL AND METHODS

A total of 1200 dental records of orofacial pain adult patients were analyzed. The outcomes were dichotomously classified (presence/absence) as following: a) AT and/or masseter palpation-induced pain; b) myogenous TMD; c) temporomandibular joint (TMJ) arthralgia (arthrogenous TMD); d) migraine; e) tension-type headache (TTH); f) self-reported bruxism. Binomial logistic regression model (α = 5%) was applied to the data considering the palpation-induced muscle pain as the dependent variable.

RESULTS

Mean age (SD) were 35.7 years (13.4) for 635 included dental records (83% females). Myogenous and arthrogenous TMD, migraine, TTH and bruxism were mainly associated with, respectively, masseter palpation-induced pain (p<0.001 - OR=5.77, 95%CI 3.86-8.62), AT or masseter palpation-induced pain (p<0.001 - OR=2.39, 95%CI 1.57-3.63), bilateral AT palpation-induced pain (p<0.001 - OR=2.67, 95%CI 1.64-4.32), masseter and AT palpation-induced pain (p=0.009 - OR=1.62, 95%CI 1.12-2.33) and bilateral masseter palpation-induced pain (p=0.01 - OR=1.74, 95%CI 1.13-2.69).

CONCLUSIONS

Palpation-induced pain in the masticatory muscles may play a role in the differential diagnosis among painful TMD, primary headaches and bruxism.

Sleep-associated aspects of myofascial pain in the orofacial area among Temporomandibular Disorder patients and controls

STUDY OBJECTIVES

To assess sleep-associated aspects of temporomandibular disorder (TMD) with myofascial pain (MP) in the orofacial area of patients and controls.

MEASUREMENTS

Three hundred five female patients were screened to find 44 participants fulfilling the inclusion criteria, 22 suffering from MP and 22 in a control group. Sleep quality was assessed by use of the Pittsburgh Sleep-Quality-Index (PSQI) and a validated German sleep questionnaire (SF-AR). Tooth wear was assessed and anterior temporalis muscle activity was measured at home for several nights by use of a portable electromyography (EMG) device.

RESULTS

22 patients (45.0 ± 13.6 years) and 22 controls (45.2 ± 9.0 years) were recruited. The PSQI sum-score was 7.5 ± 3.7 for patients and 4.4 ± 3.0 for controls (p = 0.006). The SF-AR showed that 23% of the controls and 14% of the patients were "long sleepers". The overall number of episodes in the two groups was not significantly different (4.10 ± 2.65 versus 4.57 ± 1.99 episodes per hour). However, more patients had temporalis muscle activity possibly related to SB during all four consecutive nights (p = 0.04). According to the International Classification of Sleep Disorders - Third Edition (ICSD-3) criteria, 13.6% of the controls and 71.4% of the patients (p < 0.001) showed SB.

CONCLUSIONS

Sleep-associated disturbances, including reduction of sleep quality and greater prevalence of SB and facial pain in the morning, occurred significantly more often among TMD patients. Additionally, SB fluctuated over the nights especially in controls. This should be taken into consideration when the prevalence of SB is assessed by use of EMG.

Prevalence and potential factors associated with probable sleep or awake bruxism and dentin hypersensitivity in undergraduate students

OBJECTIVE: To measure the prevalence of probable sleep or awake bruxism and cervical dentin hypersensitivity of undergraduate students and to determine the symptoms associated with these conditions.METHODOLOGY: This was a cross-sectional study. A diagnosis of probable bruxism was reached when students reported clenching or grinding of the teeth during sleep and/or wakefulness, and when they also presented some of the signs and symptoms of bruxism and masseter muscle pain on palpation. Cervical dentinal hypersensitivity was diagnosed by testing for sensitivity to pain in the cervical region of the teeth. Pain was triggered either by touch (using a #5 probe) or by an air jet spray. The sample consisted of 306 university students aged between 19 and 35 years old. The data were stored and analysed using SPSS software, version 15.0 for Windows.RESULT: The prevalence of probable bruxism was 34.3%, with no predominance regarding sex. Probable awake bruxism was more prevalent (61.9%), mostly occurring when the individual reported being in a state of mental concentration (63.1%). There was no association between probable sleep or awake bruxism and dentin hypersensitivity (p = 0.195). Individuals with probable sleep bruxism had increased odds of having muscular pain in the face upon waking (OR = 14.14, 95% CI 5.06-39.55), and those with probable awake bruxism had a increased odds of having facial muscle fatigue when chewing or talking for a long time (OR = 2.88, 95% CI 1.53-5.43) and muscular pain in the face upon waking (OR = 5.31, 95% CI 1.93-14.62).CONCLUSION: The prevalence of probable bruxism was 34.3% and that of HDC was 57.8%, with 22.2% of these subjects also showing probable bruxism. Individuals with probable bruxism tended to have a higher odds of facial pain when they awakened and when chewing or talking for long periods. There were no associations between probable sleep and awake bruxism and cervical dentin hypersensitivity.

Nocturnal masseter muscle activity is related to symptoms and somatization in temporomandibular disorders

OBJECTIVE

Temporomandibular disorders (TMD) have often been related to sleep bruxism and elevated nocturnal masseter muscle activity (NMMA). However, previous studies have revealed controversial results, and the role of somatization, depression and anxiety has not been studied in this context. The aim of this study was to investigate the association between NMMA and pain intensity, TMD related symptoms, somatoform symptoms, depression, and anxiety in chronic TMD.

METHODS

Thirty-six subjects with chronic painful TMD, 34 subjects with pain free bruxism, and 36 healthy controls recorded their nocturnal masseter muscle activity during three consecutive nights with portable devices. In addition, participants completed pain diaries and questionnaires. Diagnoses were established using the research diagnostic criteria for TMD.

RESULTS

Subjects with chronic TMD reported a reduced general health state (p<.001), higher levels of somatoform symptoms (p<.001), depression (p<.05), and anxiety (p<.001) compared to control subjects with or without sleep bruxism. The amount of NMMA did not differ significantly between the groups. In subjects with TMD, pain intensity was not related to NMMA. However, higher NMMA was related to higher intensity of jaw related symptoms such as headache or tinnitus, and higher somatization in general.

CONCLUSION

Chronic TMD is associated with elevated levels of psychopathology. These findings suggest a common link between NMMA, somatization, and symptom intensity in chronic TMD.

Relação entre dor e atividade elétrica na presença de bruxismo

OBJETIVO: mensurar a atividade elétrica dos músculos masseter e temporal, verificar a graduação de dor à palpação e sua correlação com a atividade elétrica em sujeitos com bruxismo. MÉTODO: todos os sujeitos do estudo foram selecionados após avaliação por meio do instrumento Critérios de Diagnóstico em Pesquisa para Desordens Temporomandibulares (RDC/TMD) além de avaliação odontológica e fonoaudiológica. A atividade elétrica dos músculos mastigatórios foi avaliada por meio da eletromiografia de superfície nas situações de repouso, máxima intercuspidação e mastigação habitual ritmada. Para a coleta e análise dos sinais eletromiográficos foram usados os Software BioInspector®, 1.8 (Lynx®), e software AqDAnalysis®. 7.0 (Lynx®), respectivamente, quantificados em RMS (raiz quadrada média) e expressos em µV (microvolts). A análise estatística dos dados foi realizada por meio do Coeficiente de Spearman com significância de p<0,05. RESULTADOS: os resultados mostraram que o padrão eletromiográfico dos músculos estudados apresentou-se próximos aos níveis de normalidade, no repouso, máxima intercuspidação e na mastigação habitual ritmada. A maioria dos sujeitos apresentou queixa de algum tipo de dor, sendo mais evidenciado o grau severo e, principalmente, no músculo masseter. Não evidenciou-se correlação estatisticamente significante entre dor e atividade EMG, uma vez que esta última mostrou-se próxima aos níveis de normalidade. CONCLUSÃO: a análise dos resultados indicou que, apesar da presença da dor nos músculos mastigatórios, a maioria das correlações entre dor e EMG apresentou-se fraca e sem significância estatística, indicando que a dor não interferiu no desempenho da atividade elétrica dos músculos estudados nas situações avaliadas.

Influence of psychological symptoms on home-recorded sleep-time masticatory muscle activity in healthy subjects

The present investigation attempts to describe the correlation between sleep-time masticatory muscle activity (MMA) and psychological symptoms by the use of a four-channel electromyography (EMG) home-recording device in a group of 15 healthy volunteers completing a battery of psychometric questionnaires for the assessment of anxiety, depression and anger. The integrated EMG signal was adopted to quantify the work (μV × s) produced by each of the four muscles (bilateral masseter and temporal) during the 5-h recording span and per each 1-h increment. The duration of MMA events and the muscle work during the first hour of sleep was related to trait anxiety scores for both masseter (P = 0·007) and temporalis muscles (P = 0·022). Trait anxiety was also significantly correlated to the total amount of MMA duration (in seconds) of the temporalis muscles (r = 0·558; P = 0·031). The present investigation provides support to the hypothesis that the duration of sleep-time masticatory muscle activity, especially during the early phases of a night's sleep, may be related to anxiety trait and not to anxiety state, depression or anger. These findings may support the view that features related to the individual management of anxiety, viz. trait, are likely to be more important than acute episodes of anxiety, viz. state, in the aetiology of sleep-time masticatory muscle activity. The role of other psychological symptoms is likely to be less important.

[Can orthodontic treatment generate temporomandibular disorders and pain? A review]

While considered for years to play the primary role in the etiology of temporo-mandibular joint disturbances (TMD), occlusal discrepancies are now considered to be just one causative factor among many. Recent studies, literature reviews or meta-analyses, and longitudinal studies with follow-up of children treated for many years all conclude that there is no risk of orthodontic treatment giving rise to episodes of temporo-mandibular disorders. The signs of TMD appearing during the course of orthodontic treatment should be considered in the context of the epidemiology of the disorder, which is characterized by a strong increase in its occurrence during adolescence. In conclusion, it should be stated that if orthodontic treatment can no longer be considered as one of the etiopathogenic factors in the TMD complex, there are no scientific arguments to justify the converse, that there are indications for orthodontic treatment whose sole goal would be the treatment of TMD.

Sleep disorders and their association with laboratory pain sensitivity in temporomandibular joint disorder

STUDY OBJECTIVES

We characterized sleep disorder rates in temporomandibular joint disorder (TMD) and evaluated possible associations between sleep disorders and laboratory measures of pain sensitivity.

DESIGN

Research diagnostic examinations were conducted, followed by two consecutive overnight polysomnographic studies with morning and evening assessments of pain threshold.

SETTING

Orofacial pain clinic and inpatient sleep research facility.

PARTICIPANTS

Fifty-three patients meeting research diagnostic criteria for myofascial TMD.

INTERVENTIONS

N/A.

MEASUREMENTS AND RESULTS

We determined sleep disorder diagnostic rates and conducted algometric measures of pressure pain threshold on the masseter and forearm. Heat pain threshold was measured on the forearm; 75% met self-report criteria for sleep bruxism, but only 17% met PSG criteria for active sleep bruxism. Two or more sleep disorders were diagnosed in 43% of patients. Insomnia disorder (36%) and sleep apnea (28.4%) demonstrated the highest frequencies. Primary insomnia (PI) (26%) comprised the largest subcategory of insomnia. Even after controlling for multiple potential confounds, PI was associated with reduced mechanical and thermal pain thresholds at all sites (P < 0.05). Conversely, the respiratory disturbance index was associated with increased mechanical pain thresholds on the forearm (P < 0.05).

CONCLUSIONS

High rates of PI and sleep apnea highlight the need to refer TMD patients complaining of sleep disturbance for polysomnographic evaluation. The association of PI and hyperalgesia at a nonorofacial site suggests that PI may be linked with central sensitivity and could play an etiologic role in idiopathic pain disorders. The association between sleep disordered breathing and hypoalgesia requires further study and may provide novel insight into the complex interactions between sleep and pain-regulatory processes.