International consensus on the assessment of bruxism: Report of a work in progress

Identification of Biomechanical Properties of Temporomandibular Discs

Material

Experimental and model tests were conducted on ten fresh porcine temporomandibular joint discs. The average thickness of disc tissue was, accordingly, 2.77 mm for the anterior zone, 3.98 mm for the posterior, and 1.54 mm for the intermediate. The selection of research material in the form of porcine discs was due to the similarity to human discs.

Methods

Discs were loaded in cycles, a temporary course with the amplitude 3 N and frequency 0.07 Hz, and growth in the load was 1 N/s. The selection of load frequency was due to real conditions of temporomandibular joint functioning during mastication. The necessary experimental research was conducted on a testing machine with a measurement range of 2.5 kN.

Results

The obtained numeric calculation results indicate that the number of load cycles has a decisive impact on the limitation of energy dispersion capacity through disc tissue. This phenomenon was observed in all the studies on the disc areas. Along with the growth in load cycles, discs are stiffened, and the most significant stiffness was observed in the intermediate area.

Conclusions

Based on the conducted research, it should be concluded that excessive load affecting temporomandibular joints caused by the act of mastication and occlusal forces generated during parafunction and in people with defined long-term bruxism has crucial importance on biomechanical disc properties and hence the course of temporomandibular joint conditions.

The Current Trend in Management of Bruxism and Chronic Pain: An Overview of Systematic Reviews

Bruxism, specifically sleep bruxism (SB), is a worldwide discussed topic in the literature; however, there is insufficient evidence to define and support a standard approach for the treatment of SB. The purpose of this overview was to map the evidence from systematic reviews (SR), examining the effects of interventions to improve chronic pain related to bruxism. The methodological quality of SRs was assessed using the AMSTAR-2 tool. We conducted a comprehensive literature search in April 2020, in the following databases: Cochrane Central Register of Controlled Trials, EMBASE, MEDLINE, LILACS, BBO, and Epistemonikos. Nine SRs with critically low to high methodological quality were included. Considering the main findings, botulinum toxin type A (BTX-A) showed a significant pain and sleep bruxism frequency reduction when compared to placebo or conventional treatment (behavioral therapy, occlusal splints, and drugs), after 6 and 12 months. Occlusal splints combined to muscle massage showed some benefit in pain reduction. There was no difference in pain and bruxism frequency between biofeedback therapy and an inactive control group. Regarding drug therapy, there is no difference when amitriptyline, bromocriptine, clonidine, propranolol, and levodopa were compared to placebo. In conclusion, there is some evidence to support the use of occlusal splints plus massage, and BTX-A to reduce chronic pain related to SB. No evidence was provided to support the recommendation of biofeedback therapy and drug therapy. There is still a need for more methodologically rigorous randomized clinical trials (RCT) to be conducted on the efficacy and safety of different therapies for SB.

Awake bruxism frequency and psychosocial factors in college preparatory students

OBJECTIVE

To assess the frequency of reported masticatory muscles activity during wakefulness (i.e., awake bruxism [AB]), levels of anxiety, depression, stress, and the oral health-related quality of life (OHRQoL) in college preparatory students.

METHODS

Sixty-nine college preparatory students participated in the study. AB was evaluated by the Oral Behaviors Checklist (OBC) and a smartphone-based ecological momentary assessment (EMA; [Bruxapp®]). Anxiety and depression were measured by the Hospital Anxiety and Depression Scale, stress was evaluated by the Perceived Stress Scale, and OHRQoL was obtained by The Oral Health Impact Profile-14. Data were analyzed by Pearson's correlation coefficient (α = 0.05).

RESULTS

The average EMA-reported frequency of AB behaviors was 38.4%. Significant correlations were found between AB and the OBC, anxiety, depression, stress, and OHRQoL (p < 0.001).

CONCLUSION

College preparatory students demonstrated moderate frequency of AB, which was significantly correlated with psychosocial factors.

Temporomandibular Disorders and Bruxism Outbreak as a Possible Factor of Orofacial Pain Worsening during the COVID-19 Pandemic-Concomitant Research in Two Countries

BACKGROUND

In late December 2019, a new pandemic caused by the SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) infection began to spread around the world. The new situation gave rise to severe health threats, economic uncertainty, and social isolation, causing potential deleterious effects on people's physical and mental health. These effects are capable of influencing oral and maxillofacial conditions, such as temporomandibular disorders (TMD) and bruxism, which could further aggravate the orofacial pain. Two concomitant studies aimed to evaluate the effect of the current pandemic on the possible prevalence and worsening of TMD and bruxism symptoms among subjects selected from two culturally different countries: Israel and Poland.

MATERIALS AND METHODS

Studies were conducted as cross-sectional online surveys using similar anonymous questionnaires during the lockdown practiced in both countries. The authors obtained 700 complete responses from Israel and 1092 from Poland. In the first step, data concerning TMDs and bruxism were compared between the two countries. In the second step, univariate analyses (Chi2) were performed to investigate the effects of anxiety, depression, and personal concerns of the Coronavirus pandemic, on the symptoms of TMD, and bruxism symptoms and their possible aggravation. Finally, multivariate analyses (logistic regression models) were carried out to identify the study variables that had a predictive value on TMD, bruxism, and symptom aggravation in the two countries.

RESULTS

The results showed that the Coronavirus pandemic has caused significant adverse effects on the psychoemotional status of both Israeli and Polish populations, resulting in the intensification of their bruxism and TMD symptoms.

CONCLUSIONS

The aggravation of the psychoemotional status caused by the Coronavirus pandemic can result in bruxism and TMD symptoms intensification and thus lead to increased orofacial pain.

Evaluation of jaw bone density and morphology in bruxers using panoramic radiography

Background/purpose

Bruxism affects the stomatognathic system and causes tissue damage by the excessive jaw movements. The purpose of this study was to evaluate the effects of sleep bruxism on jaw bone density, mineralisation and morphology by comparing bruxers and non-bruxers.

Materials and methods

60 bruxers and 60 non-bruxers (control) patients were included in the analysis. Cortical width at the gonion (GI), at the mental foramen (MI), at the antegonion (AI), the panoramic mandibular index (PMI), the mandibular cortical index (MCI) and antegonial notch depth (AND) were measured bilaterally on 120 panoramic radiographs. The measurements were evaluated for repeatability, correlation with age, gender and correlation between the variables.

Results

A significant association was observed between cortical shape (MCI) and bruxism status (p = 0.012). The MI was significantly different between the bruxers and non-bruxers (p = 0.006). There was a significant but weak correlation between the MI value and age in bruxers and the control (p = 0.003, p = 0.04). The AI was not associated with bruxism status and did not vary by age or gender (p > 0.05). The AND was higher in bruxers than non-bruxers (p = 0.001). Male bruxers had a significantly higher AND value than female bruxers (p = 0.001). The GI was higher in male bruxers (p = 0.001).

Conclusion

Defects in the endosteal margin of the cortex and cortical thickening in the mental region were detected in bruxer patients. Furthermore, AND was increased in bruxers. Tiny bone peaks accompanied the cortical thickening seen in the gonial region. Male bruxer patients had higher GI and AND values than female bruxers.

Music Modulates Awake Bruxism in Chronic Painful Temporomandibular Disorders

OBJECTIVE

In this experimental study, we aimed to determine whether guided music listening (GML) - a music intervention based on models of mood mediation and attention modulation - modulates masticatory muscle activity and awake bruxism in subjects with chronic painful muscular temporomandibular disorders (TMD myalgia, mTMD), a condition causing a significant burden to patients, their families, and healthcare systems.

BACKGROUND

Awake bruxism - a stress behavior characterized by clenching of the teeth - is a strong contributor to chronic mTMD. GML modulates psychological stress and motor responses and could thus reduce muscle activity in chronic musculoskeletal conditions, including mTMD.

METHODS

We recorded the electromyographic (EMG) activity in the right masseter of 14 women with chronic (>6 months) mTMD (median [IQR] = 39.5.3 [24.3] years) and 15 pain-free women (median [IQR] = 30.0 [3.5] years) during a GML session, including 3 music (stressful, relaxing, and participants' favorite music) and a no-music (pink noise) control blocks, each lasting 15 minutes. We measured the motor effort of the right masseter relative to the participants' maximum voluntary contraction (MVC), the muscular effort to maintain mandibular posture (EMG_posture ), and to produce spontaneous awake bruxism episodes (EMG_bruxism ), and the duration and frequency of spontaneous awake bruxism episodes. We tested between-group and within-group (between blocks) differences, as well as the effect of the interaction group by experimental block on these outcome measures.

RESULTS

In both groups, EMG_posture was significantly affected by the interaction group by experimental block (P < .001). Compared to pink noise [mean (95% CI); mTMD: 2.2 (1.6-2.8) %MVC; Controls: 1.1 (0.5-1.7) %MVC], EMG_posture increased during the stressful music block [contrast estimate (95% CI); mTMD: +0.8 (0.7-0.8) %MVC; Controls: +0.3 (0.3-0.4) %MVC; both P < .001], and decreased during the relaxing [mTMD: -0.4 (-0.5 to -0.4) %MVC; Controls: -0.3 (-0.4 to -0.3) %MVC; both P < .001] and favorite [mTMD: -0.5 (-0.6 to -0.5) %MVC; Controls: -0.5 (-0.5 to -0.4) %MVC; both P < .001] music blocks. EMG_posture was greater in mTMD individuals than controls during the favorite music [contrast estimate (95% CI): +1.1 (0.2-1.9) %MVC; P = .019] and the pink noise [+1.1 (0.2-2.0) %MVC; P = .014] blocks. EMG_bruxism was significantly affected by the interaction group by experimental block (P < .001). In mTMD participants, compared to the pink noise block [mean (95% CI); 23.8 (16.0-31.6) %MVC], EMG_bruxism increased during the stressful music block [contrast estimate (95% CI); +10.2 (8.6-11.8) %MVC], and decreased during the relaxing [-6.2 (-8.1 to -4.3) %MVC; P < .001] and favorite [-10.2 (-12.2 to -9.1) %MVC; P < .001] music blocks. These effects were not observed in the control group [mean (95% CI); pink noise: 19.3 (10.9-27.6); stressful: 21.2 (12.9-29.4) %MVC; relaxing: 21.6 (13.3-29.9) %MVC; favorite: 24.2 (15.8-32.7) %MVC; all P > .05]. EMG_bruxism was significantly greater in mTMD participants than controls during the stressful music block [contrast estimate (95% CI): +12.9 (1.6-24.2) %MVC; P = .026). GML did not affect the duration or the frequency of awake bruxism in either group (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108). The frequency of awake bruxism episodes was greater in the mTMD group compared to controls only during the pink noise block (median [IQR], mTMD: 5 [15.3] episodes, range 0-62 episodes; Controls: 1 [3] episode, range 0-27 episodes; P = .046). No significant between-group differences were found in either the overall time spent engaging in awake bruxism (median [IQR], mTMD: 23.5 [96.7] s, range 1-1300 seconds; Controls: 5.5 [22.5], range 0-246 seconds; P = .108), or during each block (all P > .05).

CONCLUSIONS

In subjects with chronic mTMD, relaxing music and the individual's favorite music decreased the muscular effort during spontaneous awake bruxism episodes by 26% and 44% (relative changes), respectively. In contrast, stressful music increases it by about 43%. Because of its positive effects on awake bruxism, GML with selected music could be a promising and non-invasive component of a multimodal approach for the management of chronic mTMD.

Use of a modified mandibular splint to reduce nocturnal symptoms in persons with post-traumatic stress disorder

OBJECTIVE

Based on a series of clinical observations that a thicker mandibular splint than that commonly used to treat bruxism and related craniomandibular myofascial pain reduced post-traumatic stress disorder (PTSD) nocturnal symptomatology (sleep disruptions, headaches, and nightmares), this study of 100 PTSD participants was undertaken to systematically establish 'proof of concept' of the therapeutic effectiveness of this modified splinting procedure.

METHODS

Following the fabrication of splints thicker than those conventionally used, the effectiveness of this new procedure used by dentists was determined by comparing the self-reported frequency and intensity/severity of PTSD symptomatology during a seven-night pretreatment baseline period without the splint with a second seven-night period in which the modified splint was inserted. The scoring for the three dependent measures (sleep disruptions, headaches, and nightmares) was based on the frequencies on a scale from 0-7 multiplied by the intensity/severity on a scale of 1-10.

RESULTS

Compared with the pre-splint baseline period, the insertion of the thickened splint resulted in a highly significant reduction of sleep disruption, nocturnal headaches, and nightmares. A second seven-night control period without the splint was followed by a second seven-night period with the splint, reproducing the effectiveness of the first splinting period.

CONCLUSION

The results of this study provide the first systematic, documented proof of concept of the effectiveness of a modified splinting procedure in reducing key nocturnal symptoms in PTSD patients.

Association of facial type with possible bruxism and its related clinical features in adolescents: A cross-sectional study

OBJECTIVES

The assessment of bruxism and its clinical characteristics is acknowledged in literature. This study aimed to evaluate the association of adolescents' facial patterns with bruxism and its related clinical features in the form of signs and symptoms.

MATERIALS AND METHODS

Four hundred and three adolescents answered a questionnaire evaluating sleep bruxism (SB) and awake bruxism (AB). Parents/caregivers answered a questionnaire evaluating the adolescents' sleep features (drooling on the pillow, snoring). Adolescents' facial (dolichofacial/brachyfacial/mesofacial) and clinical features (pain in masseter/temporal muscle, indentations marks on the tongue, linea alba, tooth attrition, mouth's maximum opening and masseter electrical activity) were evaluated. Multinomial regression was performed. Odds ratio (OR) and confidence intervals (CI) were provided.

RESULTS

Brachyfacial adolescents were less likely to present possible AB compared to mesofacials (OR=0.46, CI=0.21-0.98). Brachyfacial adolescents were more likely to present pain in the temporal muscle (OR=6.59, CI=2.18-19.87) and a higher number of posterior teeth with attrition (OR=1.25, CI=1.02-1.57) compared to mesofacials. Dolichofacial adolescents were more likely of not presenting pain in the masseter muscle (OR=2.23, CI=1.03-4.83), had a higher mouth's maximum opening (OR=1.43, CI=1.04-1.97), had a higher number of posterior teeth with attrition (OR=1.17, CI=1.00-1.37) and were more likely to drool on the pillow (OR=2.05, CI=1.15-3.67) compared to mesofacials. Dolichofacial adolescents were more likely of not presenting pain in the temporal muscle (OR=6.36, CI=2.30-17.54), to present themselves without marks on the tongue (OR=2.26, CI=1.09-4.69) and present a higher mouth's maximum opening (OR=2.09, CI=1.40-3.13) compared to brachyfacials.

CONCLUSION

Bruxism and its clinical features differ among dolichofacial, brachyfacial and mesofacial adolescents.

Influence of age and gender on sleep bruxism and snoring in non-apneic snoring patients: A polysomnographic study

The present study aimed to assess the influence of gender and age on snoring and sleep bruxism in non-apneic snoring patients. Adult participants with clinical suspicion of snoring and with no other significant medical history were recruited. Single-night video polysomnography was performed to detect snoring and sleep bruxism. Finally, 137 snoring non-apneic participants were included. Statistical analysis of gender groups showed that the total snore index and snore train were significantly higher in men than in women. Men also presented severe bruxism, with significantly more frequent episodes and higher bruxism episodes index scores. The correlation analysis showed the presence of significant linear relationships in the supine sleep position between age and snore index, snore index in non-rapid eye movement 2 (N2) sleep stage, and snore train. The analysis of groups separated according to the criterion of third age quartile showed that the average, maximum and minimum audio volume in the non-supine sleep position was significantly higher in the older group. The analysis of groups separated according to the criterion of median age showed that the bruxism episode index and bruxism phasic episodes were significantly higher in the younger group. Thus, it can be concluded that both age and gender influence snoring and sleep bruxism. Snoring and sleep bruxism seem to be more intensive in men. Older patients seem to snore more in N2 sleep and the supine sleep position and present lower bruxism episodes, especially the phasic type. The results of the present study indicate the need for further research on this topic to establish the possible relationship between snoring and sleep bruxism.

[Bruxism: Classification, Diagnostics and Treatment]

Bruxism: Classification, Diagnostics and Treatment Abstract. Bruxism, the grinding or clenching of teeth, is common in the population. Stress, anxiety syndromes and genetic disposition seem to be dominant factors that lead to increased muscle tension. A distinction is made between two circadian manifestations, sleep and wake bruxism. Bruxism is a major risk factor for tooth structure and dentures. The diagnosis is based on a targeted medical history and examination. Sleep bruxism can be demonstrated by electromyography and video recording in the sleep laboratory. The treatment aims to protect the hard tooth substance and preserve the denture using occlusal splints. Relaxation exercises can improve bruxism. Specialized physiotherapy can improve tension, pain and restricted movement. Botulinum toxin treatment reduces the subjective complaints during the period of action.

Correlation between Parental-Reported Tooth Grinding and Sleep Disorders: Investigation in a Cohort of 741 Consecutive Children

Purpose

A possible relationship between sleep bruxism (SB) and several sleep disorders has been suggested in children, which could influence sleep quality and quality of life. This study aims to assess such correlations in a large sample of school children.

Methods

Parents of 741 consecutive children aged between 8 and 12 years filled the Sleep Disturbance Scale for Children (SDSC). It evaluated 45 items grouped in 8 components: duration of night-time sleep, sleep latency, bedtime problems, sleep quality, night awakenings, nocturnal symptoms, morning symptoms, and daytime sleepiness. An item evaluating parental-reported tooth grinding was also included. Correlation analysis was performed between parental-reported tooth grinding and all the other items.

Results

A significant correlation between parental-reported tooth grinding and several sleep disorders concerning bedtime problems, night awakenings, nocturnal symptoms, and morning symptoms has been found. In general, correlation strength of significant pairs was low, ranging from 0.092 (sleep apnea) to 0.234 (movement while falling asleep).

Conclusions

Parental-reported tooth grinding in children is correlated, even if weakly, with some sleep disorders concerning the sphere of bedtime problems, night awakenings, nocturnal symptoms, breathing symptoms, and morning symptoms. Further studies are needed to confirm these findings, with particular regard to the consistency of correlation outcomes between the parental reports and the sleep laboratory measures.

Medications and addictive substances potentially inducing or attenuating sleep bruxism and/or awake bruxism

Bruxism is a repetitive jaw‐muscle activity characterised by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. It can occur during sleep, indicated as sleep bruxism, or during wakefulness, indicated as awake bruxism. Exogenous risk indicators of sleep bruxism and/or awake bruxism are, among others, medications and addictive substances, whereas also several medications seem to have the potential to attenuate sleep bruxism and/or awake bruxism. The objective of this study was to present a narrative literature on medications and addictive substances potentially inducing or aggravating sleep bruxism and/or awake bruxism and on medications potentially attenuating sleep bruxism and/or awake bruxism. Literature reviews reporting evidence or indications for sleep bruxism and/or awake bruxism as an adverse effect of several (classes of) medications as well as some addictive substances and literature reviews on medications potentially attenuating sleep bruxism and/or awake bruxism were used as starting point and guidelines to describe the topics mentioned. Additionally, two literature searches were established on PubMed. Three types of bruxism were distinguished: sleep bruxism, awake bruxism and non‐specified bruxism. Generally, there are insufficient evidence‐based data to draw definite conclusions concerning medications and addictive substances inducing or aggravating sleep bruxism and/or awake bruxism as well as concerning medications attenuating sleep bruxism and/or awake bruxism. There are insufficient evidence‐based data to draw definite conclusions concerning medications and addictive substances inducing or aggravating sleep bruxism and/or awake bruxism as well as concerning medications attenuating sleep bruxism and/or awake bruxism.

Relationship between self-reported bruxism and periodontal status: Findings from a cross-sectional study

BACKGROUND

Several studies seek to prove the relationship between bruxism and periodontal status although it remains unclear and debatable. We aimed to assess the association between self-reported (SR) bruxism with the periodontal status in a large scale survey.

METHODS

A total of 1064 individuals from the southern region of the Lisbon Metropolitan Area (Portugal) were enrolled. Patients were interviewed for the SR bruxism assessment through a self-report questionnaire. Full-mouth periodontal status was assessed with probing depth (PD), clinical attachment loss (CAL), gingival recession (REC), and bleeding on probing (BoP) being measured. The American Association of Periodontology/European Federation of Periodontology 2018 case definitions were used. Logistic regression analyses provided information on the influence of SR bruxism towards periodontitis.

RESULTS

SR bruxers exhibited lower prevalence of periodontitis. Additionally, SR bruxers with periodontitis had PD and CAL significantly lower than patients with only periodontitis. Multivariate analysis suggests that SR bruxism was significantly associated with a lower risk of periodontitis (odds ratio [OR] = 0.42 95% CI: 0.32-0.56). Mean PD and CAL were significantly lower in SR bruxers. When assessing the type of SR bruxism, significant differences among mean PD, CAL, and BoP levels were also identified.

CONCLUSION

SR bruxism and periodontal status are negatively associated. SR bruxers exhibit lower odds towards periodontitis and better periodontal clinical characteristics. Further studies are mandatory to clarify these findings.

A new biofeedback approach for the control of awake bruxism and chronic migraine headache: utilization of an awake posterior interocclusal device

BACKGROUND

The relationship of bidirectional comorbidity between chronic migraine and pain in the cephalic segment led us to evaluate the improvement in reducing the pain in patients diagnosed with chronic migraine headache and awake bruxism, when undergoing treatment with a partial posterior interocclusal device designed for the management and control of awake bruxism through biofeedback.

METHODS

Seventy-four patients were evaluated during the following periods: pretreatment, seven, thirty, ninety, one hundred and eighty days, and one year. The evaluation was carried out by measuring the pain in the pretreatment period and pain reduction after awake bruxism treatment, using clinical evaluation and numerical scales for pain.

RESULTS

Most of the patients who complained of headache migraine pain, masticatory myofascial pain, temporomandibular joint and neck pain experienced a significant reduction in overall pain, including headaches, between t0 and t30 (p<0.0001). After 30 days of using the device, it was observed that the improvement remained at the same level without any recurrence of pain up to t90. At t180 and t360, it was observed that even with the device withdrawal (at t90) the improvement remained at the same level.

CONCLUSION

The utilization of a posterior interocclusal device designed for the management and control of awake bruxism through biofeedback seems to contribute to the reduction of pain (including migraine headache) in the majority of patients, and, even with the device withdrawal (at t90), the improvement remained at the same level, suggesting the patients succeeded in controlling their awake bruxism and consequently the pains.

Temporomandibular Disorder: a practical guide for dental practitioners in diagnosis and management

Temporomandibular disorder is a broad term encompassing pain and/or dysfunction of the masticatory musculature and the temporomandibular joints. Pain arising from a temporomandibular disorder is a common reason for seeking dental care. It is essential that dental practitioners are able to accurately diagnose and manage this condition. Identifying people at highest risk of developing a temporomandibular disorder and knowing which procedures are more likely to initiate or exacerbate a temporomandibular disorder, are important to reduce the likelihood of its acute and chronic presentation. The aim of this paper is to provide the dental practitioner with a clinical guideline for reference including practical tools to examine, diagnose and manage patients with temporomandibular disorder. In addition the risk profile of patients and procedures is explored to help minimize the occurrence of temporomandibular disorders and mitigate its symptoms. The scope of the dental practitioner in the management of acute and chronic temporomandibular disorders is presented, with guidance about when referral to a specialist is indicated.

Occlusal Features and TMJ Clicking: A 30-Year Evaluation from a Cohort Study

Occlusal features that deviate from normative values have been historically considered risk factors for temporomandibular joint (TMJ) disorders. Nowadays, a putative association between dental occlusion and TMJ disorders remains controversial, with research findings on associations being inconsistent and inconclusive. We hypothesized that putative occlusal features identified during adolescence are associated with TMJ clicking later in life. The Dunedin Multidisciplinary Health and Development Study is a longitudinal birth cohort study investigation of 1,037 children (48.4% female) born in Dunedin, New Zealand, between April 1, 1972, and March 31, 1973, and assessed repeatedly since then. Associations between posterior crossbite, overbite, and overjet at age 15, as well as both self-reported and clinically assessed TMJ clicking sounds at age 45, were studied. Data were analyzed using multivariate logistic regression, after controlling for sex, emotional style, self-reports of tooth clenching and sleep bruxism, and history of orthodontic treatment. Self-reported and examiner-reported TMJ clicking at age 45 affected 18.3% and 23.8% of the study sample, respectively, and were not associated with the presence of a posterior crossbite or abnormal overjet/overbite values during adolescence. Self-reported history of tooth clenching and emotional style were associated with self-reported TMJ clicking later in life. In addition, there is a suggestion that high overbite during adolescence is negatively associated with TMJ clicking later in life. A history of orthodontic treatment was not associated with TMJ clicking. Abnormal occlusal features, such as posterior crossbite and high and low overjet/overbite in adolescence, are not associated with higher prevalence of TMJ clicking later in life. Personality also appears to influence self-reports of TMJ clicking later in life.

Is Otalgia be a symptom of anxiety in children?

One of the common causes of ear pain (Otalgia) in children is the pain felt in the temporomandibular region due to bruxism, usually accompanied by stress and anxiety. The diagnosis and treatment of anxiety at an early age will affect the future lives of children. Our aim in the study was to investigate the presence and subtypes of anxiety in children with otalgia due to bruxism. In our study, 86 children aged between 6 and 16 years old who had ear pain and whose pain and tenderness were detected in the temporomandibular joint area and 40 healthy children were included as the control group. The children in both study groups were administered the Spence Children's Anxiety Scale (SCAS) test by the clinical psychologist. There was no statistical correlation between the children with bruxism and normal children (p > 0.05). While anxiety rate was 82% in children with bruxism, this rate was found to be 12.5% in normal children, this result was also statistically significant (p < 0.01). According to the SCAS test, when the subscales of anxiety detected in children with bruxism were evaluated, According to the SCAS test, when the subscales of anxiety detected in children with bruxism were evaluated, it was observed that the performance anxiety was high in the 6-12 and 12-16 age group. However, obsessive symptoms were mostly observed in the 12-16 age group while separation anxiety was detected in children in the 6-12 age group.

COVID-19 and dental sleep medicine: risks, precautions and patient guidance

COVID-19 is the offcial name for the disease caused by SARS-CoV-2, which has become a pandemic, infecting more than 5 million people worldwide. Transmission occurs by inhaling droplets generated when an infected person coughs, sneezes or exhales, or by touching contaminated surfaces and then rubbing their hands over their eyes, nose or mouth. Some infected people become seriously ill, while others have no symptoms, but even though they are asymptomatic, they can still transmit the virus. As vaccines and effective medications do not yet exist, the only way to handle the devastating consequences of the pandemic is prevention. Quality of sleep is essential for the immune system to be prepared to receive, fight and restore itself after a viral infection. Therefore, patients with obstructive sleep apnea (OSA) should continue treatment, and only suspend or change the therapeutic modality under the guidance of a sleep physician. In the era of COVID-19, due to the high probability of contamination promoted by CPAP, the mandibular repositioning device has been considered as the first choice for patients with OSA. However, as the dental approach is at high risk of contamination, due to the proximity of the dental surgeon to the patient, it is essential that the professional who works in this field knows the risks to which they are exposed. Precautions must be adopted and patients should be guided in order to control and use of their intraoral devices.

Interprofessional Collaboration in Dentistry: Role of physiotherapists to improve care and outcomes for chronic pain conditions and sleep disorders

Physiotherapists can manage chronic pain patients by using technical interventions such as mobility, strengthening, manual therapy, or flexibility in a specific and functional manner, being a key component of a multidisciplinary team. Dentists are involved in the management of different chronic pain conditions such as temporomandibular disorders and sleep disorders such as obstructive sleep apnea. However, they are frequently unaware of the benefits of collaborating with physical therapists. In this review, the collaboration of physical therapists and dentists will be explored when managing orofacial pain, headaches, and sleep disorders. The physical therapist is important in the management of these disorders and also in the screening of risk factors.

Is there an association between attention deficit hyperactivity disorder in children and adolescents and the occurrence of bruxism? A systematic review and meta-analysis

Aim of the present systematic review was to evaluate whether children and adolescents with attention-deficit/hyperactivity disorder (ADHD) are at greater chance of developing bruxism compared to individuals without this disorder. Observational studies that evaluated the occurrence of bruxism in children and adolescents with ADHD were included. The quality of the evidence was evaluated using the Grading of Recommendations, Assessment, Development and Evaluation criteria. Thirty-two studies involving a total of 2629 children/adolescents with ADHD and 1739 with bruxism (1629 with sleep bruxism and 110 with awake bruxism) were included. The prevalence of bruxism, irrespective of type, in the children/adolescents was 31% (95% CI: 0.22-0.41, I² = 93%). ADHD was associated with an increased chance of bruxism (OR: 2.94, 95% CI: 2.12-4.07, I² = 61%), independently of the type [sleep bruxism (OR: 2.77, 95% CI: 1.90-4.03, I² = 66%) or awake bruxism (OR: 10.64, 95% CI: 2.41-47.03, I² = 65%)]. The presence of signs of ADHD without a diagnostic confirmation was not associated with an increased chance of bruxism (OR: 3.26, 95% CI: 0.76-14.04, I² = 61%). Children and adolescents with a definitive diagnosis of ADHD are at greater chance of developing sleep and awake bruxism than those without this disorder.

Temporomandibular joint function, periodontal health, and oral microbiome in early rheumatoid arthritis and at-risk individuals: a prospective cohort study protocol

Objectives/aims

Rheumatoid arthritis (RA) is an autoimmune disease affecting the joints, including the temporomandibular joint (TMJ). Early diagnosis and treatment can alleviate symptoms and prevent progression. Predictors for disease outcome in individuals at risk for RA are therefore valuable. While limited information is available on the prevalence of TMJ involvement in early RA, previous studies suggest that RA, periodontitis and the oral microbiome are interrelated. Predictive factors for RA development may thus be present in the oral cavity. Our two aims are: (1) to assess the prevalence of TMJ involvement in early RA, and (2) to investigate the predictive value of oral factors in RA development.

Materials and methods

We will include 150 individuals in this multi-center, prospective cohort study: 50 patients with early RA, 50 at-risk individuals, and 50 healthy controls. At baseline, the TMJ, periodontal health, and the oral microbiome will be examined. The general health will be followed over time, on four occasions up to 3 years.

Discussion

Our results will provide insight into the prevalence and clinical characterization of TMJ involvement in early RA. For at-risk individuals, oral factors can be studied as possible predictors for the development of RA.

Genetic basis of sleep bruxism and sleep apnea-response to a medical puzzle

Sleep bruxism (SB) and obstructive sleep apnea (OSA) are co-occurring sleep conditions. The study aimed to evaluate the association of selected single-nucleotide polymorphisms (SNPs) occurring within the genes of the serotonin and dopamine pathways in SB and OSA and investigate the relationship between them. The study group included 100 Caucasian patients. SB and OSA were diagnosed in 74 and 28 patients, respectively. In addition, 125 unrelated Caucasian healthy blood donors served as randomly selected controls to enable comparison of polymorphisms. The following SNPs were analyzed: rs2770304 and rs6313 within the serotonin receptor encoding gene (HTR2A), rs4680 polymorphism of the catechol-O-methyltransferase (COMT) gene, and rs686 within the dopamine receptor (DRD1) encoding gene. The prevalence of the DRD1 rs686 G variant (GG homozygosity) was found to be high in the study group compared to the control group. Bruxism episode index (BEI) was found to be significantly increased in the HTR2A rs6313 TT homozygotes compared to the heterozygous patients. Moreover, within a group of the HTR2A rs2770304 TT homozygous cases, a statistically significant correlation was observed between BEI and apnea-hypopnea index. These results indicate that DRD1 rs686 may potentially affect predisposition to SB, that HTR2A rs6313 SNP may be involved in SB pathogenesis, and that HTR2A rs2770304 polymorphism might contribute to the association between SB and OSA. This suggests a possible genetic contribution to the etiology of primary SB.

Effect of laterotrusive occlusal scheme on chewing duration, external intercostal muscular activity, heart rate, and oxygen saturation

Objective: To evaluate the effect of the laterotrusive occlusal scheme on chewing duration, external intercostal (EIC) electromyographic (EMG) activity, heart rate (HR), and oxygen saturation (OS) during different tasks in the upright seated position.Methods: Fifty young participants, 25 with canine guidance and 25 with group function, were included. Chewing duration, bilateral EIC EMG activity, HR, and OS were recorded during the following tasks: 1) chewing until swallowing threshold; 2) laterotrusive teeth grinding.Results: Chewing duration, bilateral EIC EMG activity, HR, and OS showed no significant differences between the two laterotrusive occlusal schemes during the tasks studied.Conclusion: These results suggest that chewing duration, EIC muscle activity, HR, and OS were not significantly influenced by the laterotrusive occlusal scheme. Therefore, when a modification of the laterotrusive occlusal scheme is needed during oral rehabilitation or orthodontic treatment, canine guidance or group function should not significantly change EMG activity of EIC muscles.

Coherence of jaw and neck muscle activity during sleep bruxism

BACKGROUND

Studies have shown co-contraction of jaw and neck muscles in healthy subjects during (sub) maximum voluntary jaw clenching, indicating functional inter-relation between these muscles during awake bruxism. So far, coherence of jaw and neck muscles has not been evaluated during either awake or sleep bruxism.

OBJECTIVE

The objective of this study was to evaluate the coherence between jaw and neck muscle activity during sleep bruxism.

METHODS

In a cross-sectional observational design, the electromyographic activity of jaw (masseter, temporalis) and neck (sternocleidomastoid, trapezius) muscles in individuals with "definite" sleep bruxism was measured using ambulatory polysomnography (PSG). Coherence for masseter-temporalis, masseter-sternocleidomastoid and masseter-trapezius was measured during phasic and mixed rhythmic masticatory muscle activity episodes using coherence-analysing software. Outcome measures were as follows: presence or absence of significant coherence per episode (in percentages), frequency of peak coherence (FPC) per episode and sleep stage.

RESULTS

A total of 632 episodes within 16 PSGs of eight individuals were analysed. Significant coherence was found between the jaw and neck muscles in 84.9% of the episodes. FPCs of masseter-temporalis were significantly positively correlated with those of masseter-sternocleidomastoid or masseter-trapezius (P < .001). Sleep stages did not significantly influence coherence of these muscular couples.

CONCLUSION

During sleep bruxism, jaw and neck muscle activation is significantly coherent. Coherence occurs independently of sleep stage. These results support the hypothesis of bruxism being a centrally regulated phenomenon.

Effects of Photobiomodulation in Children with Down Syndrome and Possible Sleep Bruxism: Protocol For A Randomized, Controlled, Blind, Clinical Trial: Study protocol clinical trial (SPIRIT compliant)

Hypotonia, particularly of the masticatory and oropharyngeal muscles, is 1 of the main characteristics of Down Syndrome (DS), resulting in impaired speech, chewing and swallowing. Moreover, the complete or partial obstruction of the airways during sleep may occur due to hypotonia of the tongue, leading to snoring and sleep disorders, such as obstructive apnea and sleep bruxism. OBJECTIVE:: Analyze salivary levels of dopamine and cortisol and muscle activity before and after treatment with low-level laser therapy administered to acupoints in children with DS. METHODS:: A randomized, controlled, clinical trial will be conducted. Individuals 4 to 17 years of age with a diagnosis of DS and possible sleep bruxism will be screened at the Integrated Health Clinic of Nove de Julho University. We will evaluate orofacial dysfunction (Nordic Orofacial Test - Screening questionnaire), Masseter muscle activity during sleep will be assessed by BiteStrip and the masticatory muscles will be evaluated by electromyography (BTS TMJOINT) head posture as well as salivary cortisol and dopamine. After the evaluations, the participants will be randomized into 2 groups: Grupo 1 - treatment with low-level laser therapy at a wavelength of 808 nm; Group 2 - sham treatment (simulated laser therapy). Treatment will be conducted twice per week for a total of 12 sessions. The data will be tabulated and treated using GraphPad Prism version 7.0. The Kolmogorov-Smirnov test will be used to determine the normality of the data. Variables that fit the Gaussian curve will be expressed as mean and standard deviation. The ANOVA 2-way will be used for comparisons between the groups, with the significance level set to 5% (P < .05).ClinicalTrials registration number: NCT04211870.

The association of self-reported awake bruxism with anxiety, depression, pain threshold at pressure, pain vigilance, and quality of life in patients undergoing orthodontic treatment

This study aimed to evaluate whether the presence of awake bruxism was associated with temporomandibular dysfunction symptoms, pain threshold at pressure, pain vigilance, oral health-related quality of life (OHRQoL), and anxiety and depression symptoms in patients undergoing orthodontic treatment.

Social, emotional, and behavioral problems and parent-reported sleep bruxism in schoolchildren

BACKGROUND

A number of theories associate emotional factors with the triggering of sleep bruxism (SB). Few studies have used validated instruments to assess psychological characteristics and SB in children. In this study, the authors aimed to assess the prevalence of parent-reported SB in children and its association with social, emotional, and behavioral problems.

METHODS

The authors conducted a cross-sectional study with a school-based sample at 20 public schools in Brazil. Parents or caregivers provided information related to tooth-grinding sounds during sleep and about children's social, emotional, and behavioral problems by using the Strength and Difficulties Questionnaire. Analyses were carried out considering each subscale of the Strength and Difficulties Questionnaire and the total score. The authors estimated prevalence ratios by using a Poisson regression model. Statistical inferences were based on 95% confidence intervals.

RESULTS

A total of 556 children aged 8 years were included. Prevalence of SB was 30.83%. Results of an adjusted analysis showed a significant association of SB with higher scores on total difficulties (overall score) (P < .001) and emotional symptoms (P < .001) and peer relationship problems (P = .010) subscales.

CONCLUSIONS

Parental reports of emotional and behavioral problems were associated with a higher prevalence of SB in schoolchildren.

PRACTICAL IMPLICATIONS

This study's results contribute to those of previous investigations about the association between psychological characteristics and SB. Interdisciplinary research involving dentistry and psychology may improve the understanding of bruxism.

Special Issue: Sleep Bruxism-The Controversial Sleep Movement Activity

According to the current approach [1], bruxism is considered as two different behaviours observed during sleep and wakefulness, respectively, and the single definition for bruxism has been replaced by two separate definitions [...].

Influence of respiratory allergy and restless sleep on definite sleep bruxism: a cross-sectional clinical study

OBJECTIVE

This cross-sectional clinical study evaluated the associations between sociodemographic, occupational, clinical conditions, psychological and sleep quality variables on definite sleep bruxism (SB).

METHODS

All records obtained from adults (aged 20-60 years) and the elderly (aged >60 years) who had undergone polysomnography (PSG) at a private medical outpatients' clinic from July 2017 to February 2018 were reviewed. Data from a questionnaire, based on the criteria of the American Academy of Sleep Medicine (AASM), were also gathered. Definite SB data pattern distribution was analyzed, and multivariate Poisson regression with robust variance was used to assess the associations between definite SB diagnosis, determined via PSG recordings, and the independent variables. A significance level of 5% was adopted.

RESULTS

A total of 240 individuals were included in the study and the SB prevalence was 7.08% (n = 17). The adjusted Poisson regression analysis revealed association between definitive SB and individuals with respiratory allergy (PR = 3.63; 95% CI:1.01-13; P = 0.047) and restless sleep (PR = 2.97; 95% CI:1.04-8.50; P = 0.042).

CONCLUSION

This study found associations between definite SB and clinical conditions (respiratory allergy) and sleep behavior (restless sleep). Knowledge regarding factors associated with definite SB can contribute to decision making in the clinical setting and management strategies involving a multidisciplinary approach.

Association of gender, oral habits, and poor sleep quality with possible sleep bruxism in schoolchildren

The aim of this study was to verify the oral habits, symptoms, and characteristics of some children aged 8 to 10 years that could be associated with possible sleep bruxism. A cross-sectional study was performed. Questionnaires were sent to parents to obtain information on sex, age, school shift, sleep quality, parents' perception of children's behavior, and children's oral habits (nail biting, object biting, and lip biting), and symptoms such as headache or earache. In addition, parents reported the frequency of sleep bruxism (no day to 7 days a week). Descriptive analysis and multinomial logistic regression were performed and the level of significance was set at 5%. A total of 1,554 parents of children aged 8 to 10 years participated in this study. Possible sleep bruxism was reported as mild for 65.7%, moderate for 25.3%, and severe for 9% of the children. In the adjusted multinomial logistic regression, boys were 79% more likely to have sleep bruxism (OR: 1.79; 95%CI 1.23-2.60) and were 2.06 more times at risk of being in the habit of lip biting (OR: 2.06; 95%CI 1.26-3.37). Children with possible severe sleep bruxism were 61% more likely to develop object biting (OR: 1.61; 95%CI 1.09-2.39), 52% more likely to have headaches (OR: 1.52; 95%CI 1.01-2.28), and 3.29 more times at risk of poor sleep quality (OR: 3.29; 95%CI 2.25-4.82). Based on the report, boys with lip and object biting habits, headaches, and poor sleep quality presented a higher chance of possible severe sleep bruxism.

Botulinum Toxin Therapy for Managing Sleep Bruxism: A Randomized and Placebo-Controlled Trial

The purpose of this study is to evaluate the effects of botulinum toxin type A (BoNT-A) for managing sleep bruxism (SB) in a randomized, placebo-controlled trial. Thirty SB subjects were randomly assigned into two groups evenly. The placebo group received saline injections into each masseter muscle, and the treatment group received BoNT-A injections into each masseter muscle. Audio-video-polysomnographic recordings in the sleep laboratory were made before, at four weeks after, and at 12 weeks after injection. Sleep and SB parameters were scored according to the diagnostic and coding manual of American Academy of Sleep Medicine. The change of sleep and SB parameters were investigated using repeated measures analysis of variance (RM-ANOVA). Twenty-three subjects completed the study (placebo group 10, treatment group 13). None of the SB episode variables showed a significant time and group interaction (p > 0.05) except for electromyography (EMG) variables. The peak amplitude of EMG bursts during SB showed a significant time and group interaction (p = 0.001). The injection decreased the peak amplitude of EMG bursts during SB only in the treatment group for 12 weeks (p < 0.0001). A single BoNT-A injection cannot reduce the genesis of SB. However, it can be an effective management option for SB by reducing the intensity of the masseter muscle.

Patient-based experiences with the use of an ambulatory electromyographic device for the assessment of masticatory muscle activity during sleep

Background

It is important to know how easy or difficult it is to use an ambulatory electromyographic (EMG) device for sleep bruxism assessment, and how this might affect its future utilisation.

Objective

To explore the experience of individuals using an EMG device that pairs with a smartphone app, in order to detect factors that could facilitate and/or hamper its utilisation in future scientific research.

Methods

Fifteen adults were recruited in the Orofacial Pain and Dysfunction Clinic of the Academic Centre for Dentistry Amsterdam (ACTA). Overnight recordings were performed in the home setting during one week. Time investment, feelings and thoughts, encountered difficulties and reasons for not using the device were assessed in a diary through open‐ended questions and 5‐point Likert scales. Content analysis of textual data was performed, and descriptives of quantitative data were calculated.

Results

Time investment was low (mean 10.2 minutes in the clinic, and 1.9 minutes per recording at home). Quantitative data showed an overall good experience (median of 4). Qualitative diary data showed that the desire to gain insight into one's masticatory muscle activity formed the main motivation to use the device. Device detachment and difficulty in using the app were the most prominent negative experiences.

Conclusion

The EMG device was well accepted for multiple overnight recordings. Curiosity for gaining insight into muscle activity was the most important factor that facilitated its use, and the app addressed this need. Device detachment and difficulties in using the app were the main factors that hampered its use.

Childhood Trauma, Quality of Life, Sleep Quality, Anxiety and Depression Levels in People with Bruxism

Introduction

The aim was to investigate the relation between sociodemographic features, anxiety, depression, sleep quality, childhood trauma experiences, and quality of life and bruxism determining the risk factors in people with bruxism.

Methods

A total of 200 people were included in the study. Of the patients, 100 were diagnosed with bruxism and 100 were included in the control group. Sociodemographic Data Form, Hospital Anxiety Depression Scale (HAD), The Pittsburgh Sleep Quality Index (PSQI), Childhood Trauma Scale (CTS), Short Form-36 Quality of Life Scale (SF-36) were used.

Results

While there was no significant difference between the case group and the control group in terms of age, gender, marital status, and working status, there was a significant difference between educational levels. When the groups were compared a significant difference was found with regard to HAD-A (p<0.05), HAD-D (p<0.01), PSQI (p<0.01) and CTS (p<0.05) scores. While a significant difference was found when KF-36 subscales were examined, with regard to Physical Function (p<0.01), Pain (p<0.05), Social Function (p<0.05) and Mental Health (p<0.01) scores, no significant difference was detected between the subscales of Role Strength (p>0.05), General Health (p>0.05), Vital Energy (p>0.05) and Emotional Role (p>0.05). Regression analysis shows, (PSQI), HAD-D CTS scores predicted bruxism.

Conclusion

Higher depression scale scores, bad sleep quality, traumatic childhood experiences increase the risk for bruxism. Paying attention to the mental state of people diagnosed with bruxism in the treatment process and incorporating the psychiatrists in this process may increase the success rate of the treatment.

Botulinum toxin type A for controlling bruxism assessed with computerized occlusal analysis: A pilot study

Objective: To assess botulinum toxin-A (BTX-A) on mandibular movements and bite force (BF%) in bruxism.Methods: Ten bruxers were divided into 2 groups based on BF% imbalance (G1: >10%, G2: <10%). BTX-A 140U was total injected into the masseter and temporalis muscles. A T-Scan® recorded BF%, occlusion time (OT), right, left, and protrusive disclusion time (DT) before administering BTX-A, as well as 15, 45, 90, and 120 days after injection.Results: The Friedman and Wilcoxon tests found significant differences in BF% in G1 subjects at 15 days (p = 0.028 s), OT at 90 (p = 0.043 s), and 120 (p = 0.027 s) days, DTR at 90 (p = 0.046 s) and 120 (p = 0.028 s) days, DTL at 15 (p = 0.043 s) and 90 (p = 0.027 s) days, and DTP 45_-90 days (p = 0.043 s).Conclusion: BTX-A induced BF% starting at 15 days post-injection and influenced lateralities later.

A methodology for evaluating tooth wear monitoring using timed automata modelling

OBJECTIVES

Tooth wear is a multifactorial condition leading to the loss of dental hard tissues. A counselling/monitoring protocol is of importance in order to keep that loss as limited as possible. Since many factors are involved and a time span of decades is included, research to disentangle all these processes in patients is difficult. Instead, a modelling technique was used that is able to deal with time, costs and probabilistic and stochastic information. The aim was to shed light on the question: does a yearly or a once-in-five-years counselling/monitoring protocol yield better outcome measures?

METHODS

A so-called timed automata model was adopted, analysed with the tool UPPAAL. To our knowledge, this is the first time that formal modelling is applied in dentistry. In this article, a UPPAAL model for the evaluation of tooth wear is described.

RESULTS

Using the UPPAAL model, it was calculated that with a yearly counselling/monitoring protocol the severity of tooth wear at age 74, the total costs per person and the number of restorative treatments were less, and the number of so-called "good years" was higher.

CONCLUSIONS

With the use of the UPPAAL model, it may be concluded that a yearly counselling/monitoring protocol can yield better outcome measures.

CLINICAL SIGNIFICANCE

Regarding dentistry in general and tooth wear in particular, with the use of a timed automata model in UPPAAL, actual research questions can be answered, factors of influence in a multifactorial condition like tooth wear can be clarified, and future research topics can be determined.

Sleep bruxism and oral health-related quality of life in children: A systematic review

Sleep bruxism (SB) is a masticatory muscle activity during sleep that can cause several consequences to the stomatognathic system. This systematic review investigated the impact of SB on oral health-related quality of life (OHRQoL) of 0- to 6-year-old children. Literature search was undertaken through PubMed/MEDLINE, LILACS, Scopus, TRIP, Livivo databases, and grey literature. The search was conducted with no publication year or language limits. Two reviewers independently selected the studies, extracted the data and assessed the risk of bias. The quality of evidence was assessed using GRADE. From 185 potentially eligible studies, three were included in the review. All studies were conducted in Brazil, published between 2015 and 2017, and used the B-ECOHIS instrument to evaluate OHRQoL. Two studies found no association between SB and OHRQoL, whereas one showed a significant negative impact of SB on the OHRQoL of children. SB was associated with respiratory problems, presence of tooth wear, dental caries, malocclusion as well as income and pacifier use. Risk of bias ranged from moderate to high, and the quality of evidence was judged as very low. The evidence is currently insufficient for definitive conclusions about the impact of SB on OHRQoL of children.

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.

Effects of intra-oesophageal acid infusion and a stress task on masseter muscle activity and autonomic nervous activity in wakefulness

BACKGROUND

Gastroesophageal reflux disease may be an important risk factor for awake bruxism. Additionally, it has been known that a psychological stress task affects masseter muscle activity, and autonomic nervous system (ANS) activity modulation induces masseter muscle activity.

OBJECTIVES

This study aimed to investigate whether task-induced stress and experimental oesophageal acid infusion increase masseter muscle activity and alter ANS activity, compared to rest task and oesophageal saline infusion, respectively.

METHODS

Polygraphic monitoring, consisting of electromyography of the masseter muscle and electrocardiography, was performed in 12 healthy adult men during 30-min interventions with intra-oesophageal saline or acid infusion, while reading a book quietly, as rest, and while performing calculation, as a stress task.

RESULTS

At rest, masseter muscle activity and parasympathetic nervous system (PNS) activity during acid infusion were significantly higher (P = .019) and lower (P = .021) than during saline infusion, respectively. During saline infusion, both masseter muscle activity and sympathetic nervous system (SNS) activity or PNS activity while performing the calculation task were higher (P = .022 and .012, respectively) or lower (P = .007) than those during the reading task, respectively. In two-way repeated-measures ANOVA, intra-oesophageal infusion (saline or acid) significantly affected masseter muscle activity (P = .008) and PNS activity (P = .021). However, performing tasks (reading or calculation) significantly affected only PNS activity (P = .028).

CONCLUSION

Intra-oesophageal acid infusion significantly increased masseter muscle activity and decreased PNS activity. In contrast, stress task not only significantly decreased PNS activity, but only modestly increased masseter muscle activity and SNS activity.