Effects of the D2 receptor agonist bromocriptine on sleep bruxism: report of two single-patient clinical trials

Sleep bruxism: The past, the present, and the future-evolution of a concept

BACKGROUND

The concept of sleep bruxism (SB) has evolved exponentially over the past several decades. Many theories and hypotheses have been proposed as to the definition, pathophysiology, and management of SB, from the early 1960s through the present. The role of peripheral factors, such as dental occlusion, in the pathogenesis of SB has been discarded.

TYPES OF STUDIES REVIEWED

The authors searched several electronic databases (ie, PubMed, Google Scholar, Web of Science, Embase, and Ovid MEDLINE) for studies on bruxism. The search was conducted from January 1961 through May 2023 and yielded 4,612 articles, of which 312 were selected for comprehensive review after eliminating duplicates and nonfocused articles.

RESULTS

There has been an evident progressive shift from the role of peripheral factors, such as dental occlusion, to more central factors, such as the involvement of a central pattern generator as well as the autonomic nervous system, in the genesis of bruxing movements. There is continued robust interest in the dental community to elucidate the contributing factors involved in SB.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The neurophysiology of SB appears to be leaning more toward central rather than peripheral factors. There is increasing evidence of the role of the autonomic nervous system, genetics, and comorbidities in the genesis of SB. The scientific literature seems to refute the role of dental occlusion in the causation of bruxing movements. As per the literature, there has been a paradigm shift in the definition and genesis of SB and its possible dental implications and management, which also highlights the need for succinct scientific studies in this regard.

Managements of sleep bruxism in adult: A systematic review

This systematic review aimed to update the management of sleep bruxism (SB) in adults, as diagnosed using polysomnography (PSG) and/or electromyography (EMG). Management methods covered were oral appliance therapy (OAT) with stabilization splints, cognitive-behavioral therapy (CBT), biofeedback therapy (BFT), and pharmacological therapy. A comprehensive search was conducted on MEDLINE, Cochrane Library, and Web of Science up to October 1st, 2021. Reference list searches and hand searches were also performed by an external organization. Two reviewers for each therapy independently performed article selection, data extraction, and risk of bias assessment. The reviewers resolved any disagreements concerning the assortment of the articles by discussion. Finally, 11, 3, 14, and 22 articles were selected for each therapy. The results suggested that OAT tended to reduce the number of SB events, although there was no significant difference compared to other types of splints, that the potential benefits of CBT were not well supported, and that BFT, rabeprazole, clonazepam, clonidine, and botulinum toxin type A injection showed significant reductions in specific SB parameters, although several side effects were reported. It can be concluded that more methodologically rigorous randomized large-sample long-term follow-up clinical trials are needed to clarify the efficacy and safety of management for SB.

Associations between Bruxism, Stress, and Manifestations of Temporomandibular Disorder in Young Students

Bruxism is a repetitive activity of the masticatory muscles, which determine teeth grinding or clenching, associated with rigidity, bracing, or thrusting of the mandibula. The aim of this study was to determine the prevalence of possible bruxism in 328 students attending the Faculty of Dental Medicine, University of Medicine and Pharmacy of Craiova, and its associations with stress and other manifestations of the temporo-mandibular disorder. This was a questionnaire-based study to collect information on self-evaluation of bruxism presence, frequency of specific episodes, stress, anxiety, and other manifestations of temporo-mandibular disorder. Self-evaluated bruxism was identified in 39.33% from the entire study group, allowing us to define two subgroups for further analysis. Sleep bruxism was present in 16.28% of participants; awake bruxism was present in 68.99%, while 14.73% of participants presented a combined form. The main manifestation of bruxism was reported as teeth grinding. Fatigue was identified as a common clinical sign of bruxism and temporo-mandibular disorder. Group distribution analysis (Chi-Square) indicated significant associations between bruxism and stress, panic, restlessness, or increased stress during the COVID-19 pandemic (p < 0.05). Bruxism, and especially awake bruxism, has increased in prevalence among young students, and it has been associated with increased levels of stress.

Parkinson's disease, temporomandibular disorder pain and bruxism and its clinical consequences: a protocol of a single-centre observational outpatient study

INTRODUCTION

A recent questionnaire-based study suggested that bruxism and painful temporomandibular disorders (TMD pain) may be more prevalent in patients with Parkinson's disease (PD) compared with controls. The presence of both bruxism and TMD pain may negatively influence patients' quality of life. The present study is designed to clinically and more objectively investigate the presence of bruxism and TMD pain in patients with PD. The secondary aim of the study is to identify factors associated with bruxism and TMD pain in patients with PD, such as disease severity and dopaminergic medication usage. Furthermore, the presence of tooth wear in patients with PD will be studied as this can be a major consequence of bruxism. Finally, deviations in saliva composition that may contribute to tooth wear will be studied.

METHODS AND ANALYSIS

This is a single-centre observational outpatient study at the Amsterdam University Medical Centres, location VUmc. All patients with a clinical diagnosis of PD will be eligible for inclusion. Participants will fill in a set of questionnaires. Subsequently, patients will be examined clinically for, among others, TMD pain, presence and severity of tooth wear, and deviations in saliva composition. Sleep-time registrations will take place for 5 nights with the GrindCare GC4 (ie, a portable, single-channel electromyographic recorder) to assess sleep bruxism and simultaneously by the use of the BruxApp for 5 days to assess awake bruxism. We will partly use data collected during standard clinical care to minimise patient burden.

ETHICS AND DISSEMINATION

The scientific and ethical aspects of this study protocol have been approved by the Medical Ethics Review Committee of the Amsterdam UMC, location VUmc; NL. 2019.143. Informed consent will be obtained from all participants. The results will be published in a peer-reviewed journal, if relevant presented at conferences, and published as part of a PhD thesis.

TRIAL REGISTRATION NUMBER

NL8307.

Painful Temporomandibular Disorders, Bruxism and Oral Parafunctions before and during the COVID-19 Pandemic Era: A Sex Comparison among Dental Patients

Aim: To evaluate the effect of the current coronavirus pandemic on the prevalence of bruxism, oral parafunctions and painful Temporo-Mandibular Disorders (TMDs) and to evaluate the influence of the pandemic on both sexes. Methods: This retrospective study included 288 dental patients who underwent complete anamnesis and examination according to the Diagnostic Criteria for TMD. The study evaluated two patient populations according to the date of examination: (a) pre-COVID-19 pandemic era (108 patients); (b) COVID 19 pandemic era, where 180 patients were examined during the pandemic. Results: A significant increase in parafunction activity was found in both men and women (p < 0.001) during the COVID-19 pandemic. Awake bruxism (AB) and sleep bruxism (SB) was more prevalent during the COVID-19 pandemic solely in women (AB-p < 0.001; SB-p = 0.014). Conclusions: Men and women were affected by the ongoing stress due to the COVID-19 pandemic, yet women showed a higher influence as compared to men. The long-term exposure to elevated levels of anxiety and stress may aggravate or trigger stomatognathic detrimental conditions. Dentists should be aware and regularly monitor their patients regarding the possible existence and consequences of bruxism and TMD.

Associations between sleep bruxism and other sleep-related disorders in adults: a systematic review

OBJECTIVE

Systematic reviews on sleep bruxism (SB) as a comorbid condition of other sleep-related disorders are lacking. Such reviews would contribute to the insight of sleep clinicians into the occurrence of SB in patients with other sleep-related disorders, and into the underlying mechanisms of such comorbid associations. This systematic review aimed: 1. to determine the prevalence of SB in adults with other sleep-related disorders; and 2. to determine the associations between SB and other sleep-related disorders, and to explain the underlying mechanisms of these associations.

METHODS

A systematic search on SB and sleep-related disorders was performed in PubMed, Embase, Cochrane Library, and Web of Science to identify eligible studies published until May 15, 2020. Quality assessment was performed using the Risk of Bias Assessment tool for Non-randomized Studies.

RESULTS

Of the 1539 unique retrieved studies, 37 articles were included in this systematic review. The prevalence of SB in adult patients with obstructive sleep apnea, restless leg syndrome, periodic limb movement during sleep, sleep-related gastroesophageal reflux disease, REM behavior disorder (RBD), and sleep-related epilepsy was higher than that in the general population. The specific mechanisms behind these positive associations could not be identified.

CONCLUSIONS

SB is more prevalent in patients with the previously mentioned disorders than in the general population. Sleep arousal may be a common factor with which all the identified disorders are associated, except RBD and Parkinson's disease. The associations between SB and these identified sleep-related disorders call for more SB screening in patients with the abovementioned sleep-related disorders.

N-of-1 Trials in Neurology: A Systematic Review

ObjectiveTo perform a systematic review of published N-of-1 trials (e.g. single patient cross-over trials) in neurological disorders, including an assessment of methodological quality and reporting.MethodsWe searched PubMed, MEDLINE and Embase, from inception date - the first of December 2019, for reports on N-of-1 trials in neurological disorders. Basic trial information on design, disease, intervention, analysis and treatment success was extracted. Strengths and weaknesses of the N-of-1 trials were assessed using the CONSORT extension for N-of-1 trials (CENT) 2015 criteria checklist and the Jadad score as measures of quality and reporting.ResultsWe retrieved 40 reports of N-of-1 trials in neurological disorders (19 individual N-of-1 trials, 21 series of N-of-1 trials). Most N-of-1 trials were performed in neuromuscular and neurodegenerative / movement disorders. Unlike the majority of trials that studied the main symptom(s) of a chronic stable condition, nine N-of-1 trials studied a stable chronic symptom of a progressive or acute neurological disorder. Besides pharmacological interventions, electrical stimulation protocols and nutritional products were studied. A mean total CENT score of 20.88 (SD, 9.10; range 0-43) and mean total Jadad score of 2.90 (SD, 2.15; range 0-5) were found as methodological measures of quality and reporting across all N-of-1 trialsConclusionsN-of-1 trials have been reported in numerous neurological disorders, not only in chronic stable disorders, but also in progressive or acute disorders with a stable symptom. This indicates the emerging therapeutic area of N-of-1 trials in Neurology.Methodological quality and reporting of N-of-1 trials were found suboptimal and can easily be improved in future trials by appropriately describing the methods of blinding and randomization and follow CENT guidelines. As most N-of-1 trials remain unreported in medical literature, this systematic review probably only represent the tip of the iceberg of conducted N-of-1 trials in neurological disorders. In addition to conventional trial designs, N-of-1 trials can help to bridge the gap between research and clinical care by providing an alternative, personalized level 1 evidence-base for suitable treatments.

Is dopaminergic medication dose associated with self-reported bruxism in Parkinson's disease? A cross-sectional, questionnaire-based study

OBJECTIVES

It is not clear whether dopaminergic medication influences bruxism behaviour in patients with Parkinson's disease (PD). Therefore, the aims are to investigate (i) the prevalence of possible (i.e., self-reported) bruxism (sleep and awake) in PD patients, and (ii) whether the use of dopaminergic medication and other factors (viz., demographic characteristics, PD-related factors, and possible consequences of bruxism) are associated with possible bruxism (sleep or awake).

MATERIALS AND METHODS

This study concerns a secondary analysis of an earlier published study. Three hundred ninety-five PD patients (67.9 ± 8.6 years of age; 58.7% males) were included. The levodopa equivalent daily dosage (LEDD) was used as a measure of the dopaminergic medication level. Subsequently, a logistic regression analysis was performed for the dependent variables 'awake bruxism' and 'sleep bruxism', with the following predictors: gender, age, LEDD, time since PD diagnosis, temporomandibular disorder (TMD) pain, jaw locks, and tooth wear.

RESULTS

The prevalence of possible awake and sleep bruxism was 46.0% and 24.3%, respectively. Awake bruxism was associated with sleep bruxism (OR = 8.52; 95% CI 3.56-20.40), TMD pain (OR = 4.51; 95% CI 2.31-8.79), and tooth wear (OR = 1.87; 95% CI 1.02-3.43). Sleep bruxism was associated with tooth wear (OR = 12.49; 95% CI 4.97-31.38) and awake bruxism (OR = 9.48; 95% CI 4.24-21.19). Dopaminergic medication dose was not associated with awake bruxism (OR = 1.0; 95% CI 0.99-1.00) or sleep bruxism (OR = 1.0; 95% CI 0.99-1.00).

CONCLUSION

Bruxism is a common condition in PD patients, but is not associated with the dopaminergic medication dose.

CLINICAL RELEVANCE

(Oral) health care providers should be alerted about the possibility of sleep and awake bruxism activity in PD patients, along with this activity's possible negative health outcomes (viz., TMD pain, tooth wear).

Effect of dopaminergic agonist group of drugs in treatment of sleep bruxism: A systematic review

STATEMENT OF PROBLEM

Various factors are responsible for sleep bruxism; however, whether the dopaminergic agonist group of drugs is effective in the treatment of sleep bruxism is unclear.

PURPOSE

The purpose of this systematic review was to evaluate the effect of the dopaminergic agonist group of drugs in controlling sleep bruxism in comparison with no treatment or placebo-controlled treatment.

MATERIAL AND METHODS

Two electronic databases, PubMed and Cochrane Central, were searched by using the keywords bruxism, sleep bruxism, dopamine, and dopamine agonist. After screening titles and abstracts, only those articles which met predefined inclusion criteria were selected for full-text assessment. Clinical trials using the dopaminergic agonist group of drugs as a treatment approach to sleep bruxism were included.

RESULTS

The literature search yielded a total of 64 articles from the 2 electronic databases (PubMed, 53; Cochrane Central, 11). After removal of the duplicates (n=8), the initial screening of titles and abstracts was performed by 2 independent reviewers, removing 46 articles. A total of 10 articles were selected for full-text reading, and 4 studies were included for qualitative analysis.

CONCLUSIONS

Levodopa (L-DOPA) and Bromocriptine showed decrease in root mean square value in electromyography per bruxism burst (P<.001) and 20% to 30% reduction of bruxism episodes during sleep in 2 different studies. However, treatment with bromocriptine led to conflicting result in another study in terms of frequency of bruxism episodes and amplitude of muscle contractions in electromyography (EMG). Bruxism bursts and episodes were also not significantly improved with another dopaminergic agonist group of drugs, Pramipexole (P>.001). Based on the limited evidence and conflicting results, significant conclusions cannot be generated, and further studies are required.

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.

Psychosocial Predictors of Bruxism

OBJECTIVES

The study aimed to investigate the psychosocial predictors of bruxism. The association of various psychosocial factors such as alexithymia, emotional processing, state and trait anxiety, and stress with awake bruxism was analysed.

METHODS

The study involved 52 volunteers diagnosed with awake bruxism. The toolkit that was used included the Toronto Alexithymia Scale (TAS-20), the Emotional Processing Scale (EPS), the Cohen Perceived Stress Scale (PSS-10), and the State- and Trait-Anxiety Inventory (STAI), with independent individual psychological diagnoses being made for every patient. The results were statistically analysed using IBM SPSS Statistics 24.

RESULTS

The obtained data clearly show that psychological traits-both permanent dispositions (e.g., state anxiety and alexithymia) and temporary states (e.g., trait anxiety, emotional processing deficits, and psychological stress)-are significant determinants of awake bruxism. The percentage of explained variance indicates the presence of other factors as well.

CONCLUSIONS

Psychosocial factors such as state anxiety and trait anxiety, alexithymia, and perceived stress are as important as somatic causes in the occurrence and maintenance of awake bruxism. The profile of the obtained data suggests the possibility of preventing or minimizing the symptoms of awake bruxism through properly constructed psychoprophylactic interactions.

STXBP1 encephalopathy is associated with awake bruxism

Heterozygous mutations in syntaxin-binding protein 1 (STXBP1) gene are associated with early infantile epileptic encephalopathy 4 (EIEE4). This condition is characterized by epilepsy, developmental delay (DD), and various movement disorders. Herein, we will report 5 unrelated patients with different de novo mutations in STXBP1. In addition, we conducted an online survey through Facebook to identify the incidence of bruxism (BRX) in these patients. Four out of 5 patients (80%) presented with awake BRX (A-BRX). Bruxism was also reported in 81.4% (57/70) of the patients with STXBP1 encephalopathy through the online questionnaire. No consistent correlation was identified between the type of mutation and development of movement disorders or BRX. This is the first study to demonstrate A-BRX in patients with STXBP1 mutation. Given the role of STXBP1 in exocytosis of neurotransmitters and other manifestations of dopamine dysregulation in patients with STXBP1-EIEE4, we suggest that in patients with STXBP1 encephalopathy, A-BRX might be the result of the involvement of dopaminergic circuits.

Pain perception and functional/occlusal parameters in sleep bruxism subjects following a therapeutic intervention

Background

This study was conducted to assess the individual pain perception in sleep bruxism (SB) subjects. Moreover, the effects of a cognitive behavioural therapy (CBT) compared to an occlusal appliance (OA) on pain perception and a possible continuative impact on several functional parameters were investigated.

Methods

A total of 57 SB subjects participated in this investigation. The diagnosis of SB was based on the clinical criteria of the American Academy of Sleep Medicine (AASM). Twenty-eight SB subjects were randomly allocated to the CBT group and 29 to the OA group. The therapeutic intervention took place over a period of 12 weeks, whereby both groups were examined at baseline, immediately after termination of the intervention, and at a 6-month follow-up for pain perception and functional parameters. At each of the three measurement periods, participants completed the pain perception scale and ten functional/occlusal parameters were recorded.

Results

Of the 12 parameters recorded, statistically significant main effects were found for the affective pain perception (p < 0.05) and for the three functional variables. Interestingly, the values obtained for the affective pain perception were considerably below that of a reference group. Apart from the determined statistically significant results, the values recorded for all functional/occlusal variables as well as those obtained for the sensory pain perception were clearly located within normative ranges.

Conclusions

Within the limitations of this study, it might be concluded that the significantly reduced affective pain perception in SB subjects is the expression of an adaptation mechanism.

Reevaluating Antidepressant Selection in Patients With Bruxism and Temporomandibular Joint Disorder

Temporomandibular joint disorder (TMD) is a broad pain disorder that refers to several conditions affecting the temporomandibular joint of the jaw and the muscles of mastication. As with most pain disorders, a high prevalence of depression and anxiety is associated with TMD. Research has shown that selective serotonin reuptake inhibitors (SSRIs), the first-line drug therapy for major depressive disorder, may not be suitable for TMD patients because SSRIs can induce teeth-grinding, otherwise known as bruxism. This is problematic because bruxism is believed to further exacerbate TMD. Therefore, the purpose of this literature review is to better understand the mechanism of SSRI-induced bruxism, as well as discuss alternative antidepressant options for treating depression and anxiety in patients with bruxism and TMD. Alternative classes of antidepressants reviewed include serotonin-norepinephrine reuptake inhibitors, tricyclic antidepressants, atypical antidepressants, and monoamine oxidase inhibitors. Findings indicate that dopamine agonists and buspirone are currently the most effective medications to treat the side effects of SSRI-induced bruxism, but results regarding the effectiveness of specific antidepressants that avoid bruxism altogether remain inconclusive.

Bruxism and dental implant treatment complications: a retrospective comparative study of 98 bruxer patients and a matched group

OBJECTIVES

To analyze the complications of dental implant treatment in a group of patients with bruxism in comparison with a matched group of non-bruxers.

MATERIAL AND METHODS

Patients being diagnosed as bruxers were identified within a group of patients consecutively treated with implant-supported prostheses at one specialist clinic, based on the most recent listed sign and symptoms of bruxism according to the International Classification of Sleep Disorders. A diagnostic grading system of "possible," "probable," and "definite" sleep or awake bruxism was used, according to a recent published international consensus. A case-control matching model was used to match the bruxers with a group of non-bruxers, based on five variables. Implant-, prosthetic-, and patient-related data were collected, as well as 14 mechanical complications, and compared between groups.

RESULTS

Ninety-eight of 2670 patients were identified as bruxers. The odds ratio of implant failure in bruxers in relation to non-bruxers was 2.71 (95% CI 1.25, 5.88). Considering the same number of patients with the same total number of implants equally distributed between groups, the bruxers group had a higher prevalence of mechanical complications in comparison with the non-bruxers group.

CONCLUSIONS

This study suggests that bruxism may significantly increase both the implant failure rate and the rate of mechanical and technical complications of implant-supported restorations. Other risk factors may also have influenced the results.

Association Between Self-Reported Bruxism and Malocclusion in University Students: A Cross-Sectional Study

OBJECTIVES

Bruxism can result in temporomandibular disorders, oral pain, and tooth wear. However, it is unclear whether bruxism affects malocclusion. The aim of this study was to examine the association between self-reported bruxism and malocclusion in university students.

METHODS

Students (n = 1503; 896 men and 607 women) aged 18 and 19 years were examined. Malocclusion was defined using a modified version of the Index of Orthodontic Treatment Need. The presence of buccal mucosa ridging, tooth wear, dental impression on the tongue, palatal/mandibular torus, and the number of teeth present were recorded, as well as body mass index (BMI). Additional information regarding gender, awareness of bruxism, orthodontic treatment, and oral habits was collected via questionnaire.

RESULTS

The proportion of students with malocclusion was 32% (n = 481). The awareness of clenching in males with malocclusion was significantly higher than in those with normal occlusion (chi square test, P < 0.01). According to logistic regression analysis, the probability of malocclusion was significantly associated with awareness of clenching (odds ratio [OR] 2.19; 95% confidence interval [CI], 1.22-3.93) and underweight (BMI <18.5 kg/m(2)) (OR 1.89; 95% CI, 1.31-2.71) in males but not in females. In subgroup analyses, the probability of crowding was also significantly associated with awareness of clenching and underweight (P < 0.01) in males.

CONCLUSIONS

Awareness of clenching and underweight were related to malocclusion (crowding) in university male students.

Pharmacotherapy for sleep bruxism

BACKGROUND

Sleep bruxism is an oral activity characterized by involuntary teeth grinding or clenching during sleep. Several forms of treatment have been proposed for this disorder, including behavioural, dental and pharmacological strategies.

OBJECTIVES

To evaluate the effectiveness and safety of pharmacological therapy for the treatment of sleep bruxism compared with other drugs, no treatment or placebo.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 8, 2014), MEDLINE (1966 to August 2014), EMBASE (1980 to August 2013) and LILACS (1982 to August 2014). We identified additional reports from the reference lists of retrieved reports and from reviews on treatment of sleep bruxism. We applied no language restrictions.

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) or quasi-RCTs that compared drugs with other drugs, no treatment or placebo in people with sleep bruxism.

DATA COLLECTION AND ANALYSIS

Review authors carried out data extraction and quality assessment of the included trials independently and in duplicate. We discussed discrepancies until we reached consensus. We consulted a third review author in cases of persistent disagreement. We contacted authors of primary studies when necessary.

MAIN RESULTS

We identified 18 potentially relevant RCTs, but only seven met the inclusion criteria. All studies had a small number of participants, ranging from seven to 16 people per study and had a cross-over design. Three studies were of low risk of bias, while four were of uncertain risk. Amitriptyline (three studies), bromocriptine (one study), clonidine (one study), propranolol (one study), levodopa (Prolopa®) (one study) and tryptophan (one study) were compared with placebo. Studies evaluating bromocriptine, clonidine, propranolol and levodopa reported our primary outcome of indices of bruxism motor activity.Results were imprecise and consistent with benefit, no difference or harm. These were the specific findings for each of the drugs according to specific outcomes: 1. Amitriptyline versus placebo for masseteric electromyography (EMG) activity per minute: standardized mean difference (SMD) -0.28 (95% confidence interval (CI) -0.91 to 0.34; P value = 0.37), 2. bromocriptine versus placebo for bruxism episodes per hour: mean difference (MD) 0.60 (95% CI -2.93 to 4.13), bruxism bursts per hour: MD -2.00 (95% CI -53.47 to 49.47), bruxism bursts per episode: MD 0.50 (95% CI -1.85 to 2.85) or number of episodes with grinding noise: MD 2.40 (95% CI -24.00 to 28.80), 3. clonidine versus placebo for number of bruxism episodes per hour: MD -2.41 (95% CI -4.84 to 0.02), 4. propranolol versus placebo for the number of bruxism episodes per hour: MD 1.16 (95% CI -1.89 to 4.21), 5. L-tryptophan versus placebo for masseteric EMG activity per second: SMD 0.08 (95% CI -0.90 to 1.06) and 6. levodopa versus placebo for bruxism episodes per hour of sleep: MD -1.47 (95% CI -3.64 to 0.70), for bruxism bursts per episode: MD 0.06 (95% CI -2.47 to 2.59).We combined several secondary outcomes (sleep duration, masseteric EMG activity per minute and pain intensity) in a meta-analysis for comparison of amitriptyline with placebo. The results for most comparisons were uncertain because of statistical imprecision. One study reported that clonidine reduced rapid eye movement (REM) sleep stage and increased the second stage of sleep. However, results for other sleep-related outcomes with clonidine were uncertain. Adverse effects were frequent in people who took amitriptyline (5/10 had drowsiness, difficulty awakening in the morning, insomnia or xerostomia compared with 0/10 in the placebo group), as well as in people who received propranolol (7/16 had moderate-to-severe xerostomia compare with 2/16 in the placebo group). Clonidine was associated with prolonged morning hypotension in three of 16 participants. The use of preventive medication avoided any adverse effects in people treated with levodopa and bromocriptine.

AUTHORS' CONCLUSIONS

There was insufficient evidence on the effectiveness of pharmacotherapy for the treatment of sleep bruxism. This systematic review points to the need for more, well-designed, RCTs with larger sample sizes and adequate methods of allocation, outcome assessment and duration of follow-up. Ideally, parallel RCTs should be used in future studies to avoid the bias associated with cross-over studies. There is a need to standardize the outcomes of RCTs on treatments for sleep bruxism.

Psychotropic drugs and bruxism

INTRODUCTION

Sleep and awake bruxism is defined as 'a parafunctional activity including clenching, bracing, gnashing, and grinding of the teeth'. Some evidence suggests that bruxism may be caused by, or associated with, alterations in the CNS neurotransmission. Several classes of psychotropic drugs interfering with CNS activity may potentially contribute to bruxism. Thus, the purpose of this study was to examine relevant peer-reviewed papers to identify and describe the various classes of psychotropic substances that may cause, exacerbate or reduce bruxism as the result of their pharmacological action in CNS neurons.

AREAS COVERED

A literature search from 1980 to the present was performed using PubMed database. The term 'bruxism' was used in association with 'psychotropic', 'dopamine (DA)', 'serotonin', 'histamine', 'antipsychotics', 'antidepressants', 'antihistaminergics' and 'stimulants'.

EXPERT OPINION

Studies on the effects of DA agonists (Levo-DOPA, psychostimulants) and antagonists (antipsychotics) identified a central role of DA in the pathogenesis of pharmacologically induced bruxism. Important information from studies on drugs acting on serotonin neurotransmission (antidepressants) was recognized. Other mechanisms involving different neurotransmitters are emerging. This is the case of antihistaminergic drugs which may induce bruxism as a consequence of their disinhibitory effect on the serotonergic system.

Genetic factors account for half of the phenotypic variance in liability to sleep-related bruxism in young adults: a nationwide Finnish twin cohort study

OBJECTIVES

The aim of the present study was to examine the role of genetic and environmental factors in the phenotypic variance of bruxism in a large population-based cohort of young adult twins in Finland.

METHODS

The material of the present study derives from the FinnTwin16 cohort study consisting of five birth cohorts of twin pairs born in 1975-1979 who completed a questionnaire (at mean age 24, range 23-27 years) with data on frequency of sleep-related bruxism in 2000-2002. We used quantitative genetic modeling, based on the genetic similarity of monozygotic and dizygotic twins, to estimate the most probable genetic model for bruxism, based on decomposition of phenotypic variance into components:additive genetic effects (A), dominant genetic effects (D), and non-shared environmental effects (E).

RESULTS

On average, 8.7% experienced bruxism weekly, 23.4% rarely, and 67.9% never, with no significant gender difference (p = .052). The best fitting genetic model for bruxism was the AE-model. Additive genetic effects accounted for 52% (95% Cl 0.41--0.62) of the total phenotypic variance. Sex-limitation model revealed no gender differences.

CONCLUSIONS

Genetic factors account for a substantial proportion of the phenotypic variation of the liability to sleep-related bruxism, with no gender difference in its genetic architecture.

Sleep bruxism: a comprehensive overview for the dental clinician interested in sleep medicine

Sleep bruxism (SB) is a common sleep-related motor disorder characterized by tooth grinding and clenching. SB diagnosis is made on history of tooth grinding and confirmed by polysomnographic recording of electromyographic (EMG) episodes in the masseter and temporalis muscles. The typical EMG activity pattern in patients with SB is known as rhythmic masticatory muscle activity (RMMA). The authors observed that most RMMA episodes occur in association with sleep arousal and are preceded by physiologic activation of the central nervous and sympathetic cardiac systems. This article provides a comprehensive review of the cause, pathophysiology, assessment, and management of SB.

Correlation between stress, stress-coping and current sleep bruxism

BACKGROUND

Stress is discussed as a potential factor in the development of sleep bruxism (SB). The aim of this study was to investigate whether specific stress-factors correlate with SB-activity.

METHODS

Sixty-nine subjects, of which 48 were SB-patients, completed three German questionnaires assessing different stress-parameters and stress-coping-strategies: Short questionnaire for recognition of stress-factors (Kurzer Fragebogen zur Erfassung von Belastungen, KFB), Questionnaire for recuperation and strain (Erholungs-Belastungs-Fragebogen, EBF-24 A/3) and the stress-coping questionnaire (Stressverarbeitungsfragebogen-78, SVF-78). The diagnosis of SB was based on the clinical criteria of the American Academy of Sleep Medicine (AASM). The degree of SB-activity was measured by the Bruxcore-Bruxism-Monitoring-Device (BBMD, Bruxcore, Boston, USA), worn for five consecutive nights and analyzed using a computer-based method. Non-parametric Spearman correlation coefficients, rho, were calculated between the psychometric data and the amount of SB-activity measured by a pixel score of the BBMD.

RESULTS

Significant correlations were found for 'daily problems' (r = 0.461, p < 0.01), 'trouble at work' (r = 0.293), 'fatigue' (r = 0.288), 'physical problems' (r = 0.288) and the coping-strategy 'escape' (r = 0.295) (all p < 0.05).

CONCLUSIONS

Within the limitations of this study it could be shown that subjects with high SB-activity tend to feel more stressed at work and in their daily life, which in turn might influence their physical state. These subjects also seem to deal with stress in a negative way. However, due to the rather low to almost moderate correlation coefficients and the descriptive character of the study, further investigations are necessary to examine a possible causal relationship.

Behavior analysis of electromyographic activity of the masseter muscle in sleep bruxers

The effects of occlusal splint on the electric activity of masseter were studied in 15 women who presented sleep bruxism using surface electromyography. Sleep bruxism was defined by its clinical characteristics. The signal acquisition was done during mandible occlusion without clenching and maximum voluntary contraction in two situations. The first was after a workday without using the occlusal splint; and the second, after a sleeping night using occlusal splints. Evaluating masseter muscles during mandible occlusion without clenching, it could be observed that lower values were noticed after splint wearing in both sides. The same results were verified in maximum voluntary contraction (MVC). These results confirmed that the use of occlusal splints reduced the electromyographic activity of the right and left masseters, showing its myorelaxing effect.

Urinary levels of catecholamines among individuals with and without sleep bruxism

INTRODUCTION

Sleep bruxism (SB) is characterized by repetitive and coordinated mandible movements and non-functional teeth contacts during sleep time. Although the etiology of SB is controversial, the literature converges on its multifactorial origin. Occlusal factors, smoking, alcoholism, drug usage, stress, and anxiety have been described as SB trigger factors. Recent studies on this topic discussed the role of neurotransmitters on the development of SB.

OBJECTIVE

Thus, the purpose of this study was to detect and quantify the urinary levels of catecholamines, specifically of adrenaline, noradrenaline and dopamine, in subjects with SB and in control individuals.

MATERIALS AND METHODS

Urine from individuals with SB (n = 20) and without SB (n = 20) was subjected to liquid chromatography. The catecholamine data were compared by Mann-Whitney's test (p </= 0.05).

RESULTS

Our analysis showed higher levels of catecholamines in subjects with SB (adrenaline = 111.4 microg/24 h; noradrenaline = 261,5 microg/24 h; dopamine = 479.5 microg/24 h) than in control subjects (adrenaline = 35,0 microg/24 h; noradrenaline = 148,7 microg/24 h; dopamine = 201,7 microg/24 h). Statistical differences were found for the three catecholamines tested.

CONCLUSION

It was concluded that individuals with SB have higher levels of urinary catecholamines.

Head posture and dental wear evaluation of bruxist children with primary teeth

The aim of the present study was to compare the head position and dental wear of bruxist and non-bruxist children with primary dentition.

METHODS

All the subjects had complete primary dentition, dental and skeletal class I occlusion and were classified as bruxist or non-bruxist according to their anxiety level, bruxism described by their parents and signs of temporomandibular disorders. The dental wear was drawn in dental casts and processed in digital format. Physiotherapeutic evaluation and a cephalometric radiograph with natural head position were also performed for each child to evaluate the cranio-cervical position for the bruxist group (n = 33) and the control group (n = 20). The variables of the two groups were compared, using the Student t-test and Mann-Whitney U-test.

RESULTS

A more anterior and downward head tilt was found in the bruxist group, with statistically significant differences compared with the controls. More significant dental wear was observed in the bruxist children.

CONCLUSIONS

Bruxism seems to be related to altered natural head posture and more intense dental wear. Further studies are necessary to explore bruxism mechanisms.

ADHD, bruxism and psychiatric disorders: does bruxism increase the chance of a comorbid psychiatric disorder in children with ADHD and their parents?

There is an association between bruxism and ADHD. No published data on psychiatric comorbidities in attention-deficit/hyperactivity disorder (ADHD) children with bruxism were found. There is no satisfying treatment method for children with bruxism. If we understand its comorbidities well, a better treatment method could come out. This study was conducted to compare the frequency of comorbid psychiatric disorders in the parents and their ADHD children with and without teeth grinding. It was hypothesized that there is no association between bruxism and prevalence of comorbid psychiatric disorders in children with ADHD and their parental psychopathology. Eighty-nine ADHD children without teeth grinding were compared with 32 ADHD children with teeth grinding. Their parental psychiatric disorders were also compared. Structured interviews were used to diagnose comorbid psychiatric disorders. The demographic characteristics of the children and their parents were not different between the groups. The only psychiatric disorder in children, which was associated with the groups was oppositional defiant disorder. The rate of conduct disorder, tic disorder, major depressive disorder, separation anxiety disorder, generalized anxiety disorder, enuresis, and obsessive compulsive disorder were not different between the two groups of children. The rate of major depression was more in the mothers of children with teeth grinding than those without such children. These finding were not reported before. ADHD children with teeth grinding have a high prevalence of oppositional defiant disorder. Lack of association between anxiety disorder and presence of teeth grinding might not support the idea that anxiety is associated with teeth grinding. The association of ODD and teeth girding might be a clue about etiology of bruxism. Perhaps, this clue can probably lead to the development of a more satisfying treatment. With consideration of this clue, further studies should survey if there is any association between ODD and sleep micro-arousals.

Occlusal splints for treating sleep bruxism (tooth grinding)

BACKGROUND

Sleep bruxism is an oral activity characterised by teeth grinding or clenching during sleep. Several treatments for sleep bruxism have been proposed such as pharmacological, psychological, and dental.

OBJECTIVES

To evaluate the effectiveness of occlusal splints for the treatment of sleep bruxism with alternative interventions, placebo or no treatment.

SEARCH STRATEGY

We searched the Cochrane Oral Health Group's Trials Register (to May 2007); the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2007, Issue 1); MEDLINE (1966 to May 2007); EMBASE (1980 to May 2007); LILACS (1982 to May 2007); Biblioteca Brasileira de Odontologia (1982 to May 2007); Dissertation, Theses and Abstracts (1981 to May 2007); and handsearched abstracts of particular importance to this review. Additional reports were identified from the reference lists of retrieved reports and from article reviews about treating sleep bruxism. There were no language restrictions.

SELECTION CRITERIA

We selected randomised or quasi-randomised controlled trials (RCTs), in which splint therapy was compared concurrently to no treatment, other occlusal appliances, or any other intervention in participants with sleep bruxism.

DATA COLLECTION AND ANALYSIS

Data extraction was carried out independently and in duplicate. Validity assessment of the included trials was carried out at the same time as data extraction. Discrepancies were discussed and a third review author consulted. The author of the primary study was contacted when necessary.

MAIN RESULTS

Thirty-two potentially relevant RCTs were identified. Twenty-four trials were excluded. Five RCTs were included. Occlusal splint was compared to: palatal splint, mandibular advancement device, transcutaneous electric nerve stimulation, and no treatment. There was just one common outcome (arousal index) which was combined in a meta-analysis. No statistically significant differences between the occlusal splint and control groups were found in the meta-analyses.

AUTHORS' CONCLUSIONS

There is not sufficient evidence to state that the occlusal splint is effective for treating sleep bruxism. Indication of its use is questionable with regard to sleep outcomes, but it may be that there is some benefit with regard to tooth wear. This systematic review suggests the need for further investigation in more controlled RCTs that pay attention to method of allocation, outcome assessment, large sample size, and sufficient duration of follow up. The study design must be parallel, in order to eliminate the bias provided by studies of cross-over type. A standardisation of the outcomes of the treatment of sleep bruxism should be established in the RCTs.

Botulinum toxin in the treatment of tremors, dystonias, sialorrhea and other symptoms associated with Parkinson's disease

Botulinum toxins are an effective treatment modality for a growing number of neurologic conditions. Although there has been varied interest and success in their use, they have been studied for a variety of conditions associated with Parkinson's disease. Conditions reviewed in this paper include hand and jaw tremor, dystonia, blepharospasm and apraxia of eyelid opening, bruxism, camptocormia, freezing of gait, sialorrhea and constipation. We will make comments when applicable on our unique experience with botulinum toxin in these conditions. Other conditions associated with Parkinson's disease, which will not be reviewed here, but may benefit from botulinum toxin treatment include anterocollis (also known as dropped head syndrome), hyperhidrosis, seborrhea and overactive bladder.

Effects of pergolide on severe sleep bruxism in a patient experiencing oral implant failure

In the patient described in this study, oral implants failed as a probable consequence of severe, polysomnographically confirmed sleep bruxism. As this patient had the wish to be re-implanted after this failure, we decided to try diminishing the frequency of bruxism and duration first. To that end, two management strategies were used. Their efficacy was evaluated polysomnographically, yielding a total of six overnight recordings. Of the selected management strategies, the administration of low doses of the dopamine D1/D2 receptor agonist pergolide finally resulted in a substantial and lasting reduction in the bruxism outcome measures under study. This result supports the previous suggestion that central neurochemicals like dopamine may be involved in the modulation of sleep bruxism. The case report also illustrates the importance of an extensive history taking (questionnaires as well as oral) and clinical examination of oral implant patients for the presence of severe bruxism before the implant procedure is started. In case of doubt, polysomnography may be considered to definitively confirm or rule out the presence of severe sleep bruxism.

Effects of an occlusal splint compared with cognitive-behavioral treatment on sleep bruxism activity

The impact of an occlusal splint (OS) compared with cognitive-behavioral treatment (CBT) on the management of sleep bruxism (SB) has been poorly investigated. The aim of this study was to evaluate the efficacy of an OS with CBT in SB patients. Following a randomized assignment, the OS group consisted of 29, and the CBT group of 28, SB patients. The CBT comprised problem-solving, progressive muscle relaxation, nocturnal biofeedback, and training of recreation and enjoyment. The treatment took place over a period of 12 wk, and the OS group received an OS over the same time period. Both groups were examined pretreatment, post-treatment, and at 6 months of follow-up for SB activity, self-assessment of SB activity and associated symptoms, psychological impairment, and individual stress-coping strategies. The analyses demonstrated a significant reduction in SB activity, self-assessment of SB activity, and psychological impairment, as well as an increase of positive stress-coping strategies in both groups. However, the effects were small and no group-specific differences were seen in any dependent variable. This is an initial attempt to compare CBT and OS in SB patients, and the data collected substantiate the need for further controlled evaluations, using a three-group randomized design with repeated measures to verify treatment effects.

A proposed mechanism for diurnal/nocturnal bruxism: hypersensitivity of presynaptic dopamine receptors in the frontal lobe

There are many reports in the literature concerning nocturnal bruxism, however, diurnal (non-sleep)/nocturnal bruxism is rarely mentioned. We report three patients with diurnal/nocturnal bruxism. They differed from the usual features of nocturnal bruxism in hypoperfusion of the left frontal lobe, a poor response to l-dopa or bromocriptine therapy and a favourable response to metoclopramide. Hypersensitive presynaptic dopamine receptors may be the underlying pathology responsible for this type of bruxism. Regional differences in dopamine receptor pharmacology may explain the perplexing relationship of bruxism to both hyper- and hypo-dopaminergic states.

Mood disorders in subjects with bruxing behavior

OBJECTIVE

An investigation was conducted on 105 subjects to assess the existence of an association between mood psychopathology and bruxism.

METHODS

Validated clinical criteria were used to diagnose bruxism and a self-report validated questionnaire (MOODS-SR) was filled out by each patient for an evaluation of depression and mania symptoms of mood spectrum.

RESULTS

Prevalence of mood psychopathology, as identified by MOODS-SR score> or =60, was significantly higher in bruxers (11/38, 28.9% vs. 6/67, 8.9%; P=0.007). Significant differences between bruxers and non-bruxers also emerged in total MOODS-SR (P=0.001) scores and in total scores of domains evaluating manic (P=0.001) and depressive symptoms (P=0.007).

CONCLUSIONS

Support to the existence of an association between bruxism and mood disorders has been provided. Further studies are strongly needed to clarify mechanisms underlying the described association.

Psychic and occlusal factors in bruxers

BACKGROUND

The aim of this study was to investigate the existence of associations between bruxism and psychic and occlusal factors.

METHODS

Participants in this study (n=85) were recruited from the Section of Odontostomatology, Deparent of Neuroscience, University of Pisa, Italy. They were split into two groups, bruxers (n=34) and non-bruxers (n=51), on the basis of the presence of both clinical and anamnestical indicators of bruxim. All participants were administered two self-reported validated questionnaires to evaluate (MOODS-SR) and panic-agoraphobic (PAS-SR) spetra. A number of occlusal variables (deep-bite: cross-bite, open-bite, mediotrusive and laterotrusive interferences, slide RCP-ICP, laterotrutsive guides, canine and molar classes) were also recorded.

RESULTS

With regards to occlusal factors, the only association was revealed between bruxism mediotrusive interferences (p < 0.05). As for psychiatric investigation, significant differences between bruxers and controls emerged for the presence of both depressive (p < 0.01) and manic symptoms (p < 0.01) in MOODS-SR, and for stress sensitivity (p < 0.01), anxious expectation (p < 0.05), and reassurance sensitivity symptoms (p < 0.05) in PAS-SR. In particular, both mood (p < 0.01) and panic-agoraphobic (p < 0.05) spectra symptoms seem to differentiate bruxers from controls in males, while in females strong differences emerged for stress sensitivity symptoms (p < 0.05).

CONCLUSIONS

It can be confirmed that certain psychic traits are present in bruxers, while occlusal factors are not useful parameters to discern bruxers from non-bruxers.