Neurobiological mechanisms involved in sleep bruxism.
Sleep bruxism (SB) is reported by 8% of the adult population and is mainly associated with rhythmic masticatory muscle activity (RMMA) characterized by repetitive jaw muscle contractions (3 bursts or more at a frequency of 1 Hz). The consequences of SB may include tooth destruction, jaw pain, headaches, or the limitation of mandibular movement, as well as tooth-grinding sounds that disrupt the sleep of bed partners. SB is probably an extreme manifestation of a masticatory muscle activity occurring during the sleep of most normal subjects, since RMMA is observed in 60% of normal sleepers in the absence of grinding sounds. The pathophysiology of SB is becoming clearer, and there is an abundance of evidence outlining the neurophysiology and neurochemistry of rhythmic jaw movements (RJM) in relation to chewing, swallowing, and breathing. The sleep literature provides much evidence describing the mechanisms involved in the reduction of muscle tone, from sleep onset to the atonia that characterizes rapid eye movement (REM) sleep. Several brainstem structures (e.g., reticular pontis oralis, pontis caudalis, parvocellularis) and neurochemicals (e.g., serotonin, dopamine, gamma aminobutyric acid [GABA], noradrenaline) are involved in both the genesis of RJM and the modulation of muscle tone during sleep. It remains unknown why a high percentage of normal subjects present RMMA during sleep and why this activity is three times more frequent and higher in amplitude in SB patients. It is also unclear why RMMA during sleep is characterized by co-activation of both jaw-opening and jaw-closing muscles instead of the alternating jaw-opening and jaw-closing muscle activity pattern typical of chewing. The final section of this review proposes that RMMA during sleep has a role in lubricating the upper alimentary tract and increasing airway patency. The review concludes with an outline of questions for future research. (+info)
Tiagabine may reduce bruxism and associated temporomandibular joint pain.
Tiagabine is an anticonvulsant gamma-aminobutyric acid reuptake inhibitor commonly used as an add-on treatment of refractory partial seizures in persons over 12 years old. Four of the 5 cases reported here indicate that tiagabine might also be remarkably effective in suppressing nocturnal bruxism, trismus, and consequent morning pain in the teeth, masticatory musculature, jaw, and temporomandibular joint areas. Tiagabine has a benign adverse-effect profile, is easily tolerated, and retains effectiveness over time. Bed partners of these patients report that grinding noises have stopped; therefore, the tiagabine effect is probably not simply antinociceptive. The doses used to suppress nocturnal bruxism at bedtime (4-8 mg) are lower than those used to treat seizures. (+info)
Bruxism in children: a warning sign for psychological problems.
Bruxism is nonfunctional clenching or grinding of the teeth. It is a destructive habit that may result in tooth wear. Although research on bruxism is extensive, its etiology remains debatable. The literature suggests that bruxism is correlated with both experienced and anticipated life stress. The purpose of this report is to describe 2 cases of severe bruxism in children of similar age with different life histories and to discuss the factors that could have triggered this parafunctional condition. (+info)
Sleep bruxism is associated to micro-arousals and an increase in cardiac sympathetic activity.
Sleep bruxism (SB) subjects show a higher incidence of rhythmic masticatory muscle activity (RMMA) than control subjects. RMMA is associated with sleep micro-arousals. This study aims to: (i) assess RMMA/SB episodes in relation to sleep cycles; (ii) establish if RMMA/SB and micro-arousals occur in relation to the slow wave activity (SWA) dynamics; (iii) analyze the association between RMMA/SB and autonomic cardiac activity across sleep cycles. Two nights of polygraphic recordings were made in three study groups (20 subjects each): moderate to high SB, low SB and control. RMMA episodes were considered to occur in clusters when several groups of RMMA or non-specific oromotor episodes were separated by less than 100 s. Correlations between sleep, RMMA/SB index and heart rate variability variables were assessed for the first four sleep cycles of each study group. Statistical analyses were done with SYSTAT and SPSS. It was observed that 75.8% of all RMMA/SB episodes occurred in clusters. Micro-arousal and SB indexes were highest during sleep cycles 2 and 3 (P < 0.001). Within each cycle, micro-arousal and RMMA/SB indexes showed an increase before each REM sleep (P +info)
Prevalence of bruxism among Mexican children with Down syndrome.
This study sought to determine the prevalence of bruxism in a Mexican community of children with Down syndrome, and to evaluate bruxism's relationship with age, sex, intellectual disability level, and type of chromosomal abnormality of trisomy 21. Using a cross-sectional design, 57 boys and girls (3 to 14 years old) were examined. Three approaches to establish presence or absence of bruxism were employed: parental questionnaire, clinical examination, and dental study casts. Data were analysed using bivariate analyses and conditional logistic regression. We found that the overall prevalence of bruxism was 42%. No statistically significant associations between bruxism and age, sex, or intellectual disability level were found. There was, however, a significant association between bruxism and type of chromosomal abnormality, with mosaicism being more frequently associated with bruxism. (+info)
Weighing the potential effectiveness of various treatments for sleep bruxism.
Sleep bruxism may lead to a variety of problems, but its pathophysiology has not been completely elucidated. As such, there is no definitive treatment, but certain preventive measures and/or drugs may be used in acute cases, particularly those involving pain. This article is intended to guide clinician scientists to the treatment most appropriate for future clinical studies. To determine the best current treatment, 2 measures were used to compare the results of 10 clinical studies on sleep bruxism, 3 involving oral devices and 7 involving pharmacologic therapy. The first measure, the number needed to treat (NNT), allows several randomized clinical studies to be compared and a general conclusion to be drawn. The second measure, effect size, allows evaluation of the impact of treatment relative to a placebo using different studies of similar design. Taking into account the NNT, the effect size and the power of each study, it can be concluded that the following treatments reduce sleep bruxism: mandibular advancement device, clonidine and occlusal splint. However, the first 2 of these have been linked to adverse effects. The occlusal splint is therefore the treatment of choice, as it reduces grinding noise and protects the teeth from premature wear with no reported adverse effects. The NNT could not be calculated for an alternative pharmacologic treatment, short-term clonazepam therapy, which had a large effect size and reduced the average bruxism index. However, the risk of dependency limits its use over long periods. Assessment of efficacy and safety of the most promising treatments will require studies with larger sample sizes over longer periods. (+info)
Associations of reported bruxism with insomnia and insufficient sleep symptoms among media personnel with or without irregular shift work.