Maria Clotilde Carra

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.

Prevalence and risk factors of sleep bruxism and wake‐time tooth clenching in a 7‐ to 17‐yr‐old population

Sleep-related bruxism (SB) and wake-time tooth clenching (TC) have been associated with temporomandibular disorders (TMDs), headache, and sleep and behavioral complaints. This study aimed to assess the prevalence and risk factors of these signs and symptoms in a 7- to 17-yr-old population (n = 604) seeking orthodontic treatment. Data were collected by questionnaire and by a clinical examination assessing craniofacial morphology and dental status. Sleep-related bruxism was reported by 15% of the population and TC was reported by 12.4%. The SB group (n = 58) was mainly composed of children (67.3% were ≤12 yr of age) and the TC group (n = 42) was mainly composed of adolescents (78.6% were ≥13 yr of age). The craniofacial morphology of over 60% of SB subjects was dental class II and 28.1% were a brachyfacial type. Compared with controls (n = 220), SB subjects were more at risk of experiencing jaw muscle fatigue [adjusted OR (AOR) = 10.5], headache (AOR = 4.3), and loud breathing during sleep (AOR = 3.1). Compared with controls, TC subjects reported more temporomandibular joint clicking (AOR = 5), jaw muscle fatigue (AOR = 13.5), and several sleep and behavioral complaints. Sleep- and wake-time parafunctions are frequently associated with signs and symptoms suggestive of TMDs, and with sleep and behavioral problems. Their clinical assessment during the planning of orthodontic treatment is recommended.

Sleep bruxism and sleep arousal: an experimental challenge to assess the role of cyclic alternating pattern

Rhythmic masticatory muscle activity (RMMA) is the characteristic electromyographic pattern of sleep bruxism (SB), a sleep-related motor disorder associated with sleep arousal. Sleep arousals are generally organised in a clustered mode known as the cyclic alternating pattern (CAP). CAP is the expression of sleep instability between sleep maintaining processes (phase A1) and stronger arousal processes (phases A2 and A3). This study aimed to investigate the role of sleep instability on RMMA/SB occurrence by analysing CAP and electroencephalographic (EEG) activities. The analysis was performed on the sleep recordings of 8 SB subjects and 8 controls who received sensory stimulations during sleep. Baseline and experimental nights were compared for sleep variables, CAP, and EEG spectral analyses using repeated measure ANOVAs. Overall, no differences in sleep variables and EEG spectra were found between SB subjects and controls. However, SB subjects had higher sleep instability (more phase A3) than controls (P= 0·05). The frequency of phase A3 was higher in the pre-REM sleep periods (P < 0·001), where peaks in RMMA/SB activity were also observed (P = 0·05). When sleep instability was experimentally increased by sensory stimuli, both groups showed an enhancement in EEG theta and alpha power (P = 0·04 and 0·02, respectively) and significant increases in sleep arousal and all CAP variables. No change in RMMA/SB index was found within either groups (RMMA/SB occurred in all SB subjects and only one control during the experimental night). These findings suggest that CAP phase A3 may act as a permissive window rather than a generator of RMMA/SB activity in predisposed individuals.

Does Sleep Differ Among Patients with Common Musculoskeletal Pain Disorders

Most patients with chronic musculoskeletal pain report poor-quality sleep. The impact of chronic pain on sleep can be described as a vicious circle with mutual deleterious influences between pain and sleep-associated symptoms. It is difficult, however, to extract quantitative or consistent and specific sleep variables (eg, total sleep time, slow-wave sleep, sleep stage duration) that characterize the pain-related disruption of sleep. Comorbidity (eg, fatigue; depression; anxiety, sleep, movement, or breathing disorders) often confounds the reading and interpretation of sleep traces. Furthermore, many other methodologic issues complicate our ability to generalize findings (low external validity) to first-line medicine. Because sleep alterations in common musculoskeletal pain are neither specific nor pathognomonic, the aim is to provide a critical overview of the current understanding of pain and sleep interaction, discussing evidence-based and empiric knowledge that should be considered in further research and clinical applications.

Sleep bruxism, snoring, and headaches in adolescents: short-term effects of a mandibular advancement appliance.

OBJECTIVES Sleep bruxism (SB) frequently is associated with other sleep disorders and pain concerns. Our study assesses the efficacy of a mandibular advancement appliance (MAA) for SB management in adolescents reporting snoring and headache (HA). METHODS Sixteen adolescents (mean age, 14.9±0.5) reporting SB, HA (>1d/wk), or snoring underwent four ambulatory polysomnographies for baseline (BSL) and while wearing MAA during sleep. MAA was worn in three positions (free splints [FS], neutral position [NP], and advanced to 50% of maximum protrusion [A50]) for 1 week each in random order (FS-NP-A50 or NP-A50-FS; titration order, NP-A50). Reports of HA were assessed with pain questionnaires. RESULTS Overall, sleep variables did not differ across the four nights. SB index decreased up to 60% with MAA in A50 (P=.004; analysis of variance). Snoring was measured as the percentage of sleep time spent snoring. The subgroup of snorers (n=8) showed significant improvement with MAA (-93%; P=.002). Initial HA intensity was reported at 42.7±5/100 mm, showing a decreasing trend with MAA (-21% to -51%; P=.07). CONCLUSION Short-term use of an MAA appears to reduce SB, snoring, and reports of HA. However, interactions between SB, breathing during sleep, and HA as well as the long-term effectiveness and safety of MAA in adolescents need further investigation.

Females with sleep bruxism show lower theta and alpha electroencephalographic activity irrespective of transient morning masticatory muscle pain.

AIMS To investigate the hypothesis that the presence of transient morning masticatory muscle pain in young, healthy sleep bruxers (SBr) is associated with sex-related differences in sleep electroencephalographic (EEG) activity. METHODS Data on morning masticatory muscle pain and sleep variables were obtained from visual analog scales and a second night of polysomnographic recordings. Nineteen normal control (CTRL) subjects were age- and sex-matched to 62 tooth-grinding SBr. Differences in sleep macrostructure (stage distribution and duration, number of sleep-stage shifts), number of rhythmic masticatory muscle activity (RMMA) events÷ hour, and EEG activity were analyzed blind to subject status. The influence of pain and gender in SBr and CTRL subjects was assessed with the Fishers exact test, Mann-Whitney U test, two-sample t test, and analysis of variance (ANOVA). RESULTS Low-intensity morning transient orofacial pain was reported by 71% of SBr, with no sex difference. RMMA event frequency was higher in SB than CTRL subjects (4.5÷hour vs 1.3÷hour; P < .001). SBr had fewer sleep-stage shifts, irrespective of sex or pain status. Female SBr had significantly lower theta and alpha EEG activity compared to female CTRL subjects (P = .03), irrespective of pain. CONCLUSION Female SBr had lower theta and alpha EEG activity irrespective of transient morning pain.