Sleep Bruxism Subjects Research Articles

A Significant Increase in Breathing Amplitude Precedes Sleep Bruxism

Sleep bruxism (SB) is a stereotyped movement disorder that is characterized by rhythmic masticatory muscle activity (RMMA) and tooth grinding. Evidence has suggested that SB is associated with sleep arousals and that most RMMA episodes are preceded by physiologic changes occurring in sequence, namely, a rise in autonomic sympathetic-cardiac activity followed by a rise in the frequency of EEG and suprahyoid muscle activity. In the present study, we hypothesize that an increase in respiration also characterizes the onset of SB within the arousal sequence. Polygraphic sleep recordings of 20 SB subjects without any sleep-related breathing disorders were analyzed for changes in respiration (ie, root mean square, area under the curve, peak, peak-to-peak, and length) extracted from a nasal cannula signal. Variables were analyzed and compared using analysis of variance and correlation tests. Measurements of respiration showed significant changes over time. Four seconds before RMMA muscle activity, the amplitude of respiration is already increased (8 to 23%); the rise is higher at the onset of the suprahyoid activity (60 to 82% 1 s before RMMA); the rise is maximal during RMMA (108 to 206%) followed by a rapid return to levels preceding RMMA. A positive and significant correlation was found between the frequencies of RMMA episodes and the amplitude of breath (R(2) = 0.26; p = 0.02). The amplitude of respiratory changes was 11 times higher when arousal was associated with RMMA in comparison to arousal alone. To our knowledge, this is the first report showing that RMMA-SB muscle activity is associated with a rise in respiration within arousal.

In vivo evaluation of noncarious cervical lesions in sleep bruxism subjects

Occlusal load has frequently been suggested to be involved in the development of a noncarious cervical lesion (NCL). However, there is a lack of clinical studies evaluating NCLs and occlusal parameters in sleep bruxism (SB) subjects. The purpose of this clinical study was to assess the frequency of NCLs and determine potential occlusal differences between SB subjects and healthy control subjects. A total of 91 volunteers, 58 women and 33 men, with a mean (SD) age of 28.37 (4.89) years (range of 20 to 39 years), participated in this investigation. The clinical assessment of SB was based on the criteria of the American Academy of Sleep Medicine. The participants were divided into 2 groups; 58 subjects were assigned to the SB group and 33 subjects to the control group, following a thorough dental examination that was performed by a single trained dentist. Additionally, the following parameters were recorded: mean number of teeth present, existence/absence of NCLs, frequency of NCLs relating to the type of tooth, type of occlusal guidance scheme, existence of a slide from centric occlusion (CO) to maximum intercuspation (MI), length of the slide, and report of tooth hypersensitivity. Group differences were statistically analyzed using chi-square tests for the qualitative variables and Mann-Whitney U tests for the quantitative variables (alpha=.05). NCLs were significantly more prevalent in SB subjects (39.7%) than in the control subjects (12.1%) (P=.006). In SB subjects, the first premolars were the teeth most affected, and in control subjects, the first molars were most affected. Tooth hypersensitivity was reported in 62.1% of the SB subjects and in 36.4% of the control subjects (P=.018). The evaluation of occlusal guidance schemes revealed no significant difference between the groups. In SB subjects (70.7%), a slide from CO to MI was significantly more prevalent than in control subjects (42.4%) (P=.008). Moreover, SB subjects demonstrated a significantly longer mean (SD) slide of 0.77 (0.69) mm compared to that of control subjects of 0.4 (0.57) mm (P=.008). Within the limitations of this study, SB subjects demonstrated significantly more NCLs than the control group; whereas, the type of occlusal guidance scheme seems to be of minor importance in the development of NCLs.

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 <or= 0.02). The cross-correlation plot for micro-arousal index showed positive association from 4 min preceding SB onset in the moderate to high SB subjects (P <or= 0.06). The cross-correlation plot revealed that SWA decreases following SB onset (P <or= 0.05). Further cross-correlation analysis revealed that a shift in sympatho-vagal balance towards increased sympathetic activity started 8 min preceding SB onset (P <or= 0.03). In moderate to severe SB subjects, a clear increase in sympathetic activity precedes SB onset.

Sleep bruxism; an overview of an oromandibular sleep movement disorder. REVIEW ARTICLE.

Sleep bruxism (SB) is a stereotyped movement disorder characterized by grinding or clenching of the teeth during sleep. The majority of the population will at some time during their lifetime grind or clench their teeth. It becomes a pathological condition when the subject presents severe tooth damage or complains of non-restorative sleep. The prevalence of SB is difficult to estimate, since quite often the subjects are unaware of having the disorder. There is no gender difference. SB is more frequent in the younger generation, with a decline over age. The symptom recognized in children can persist in adulthood. The aetio-pathophysiology is still unclear. SB has been associated with tooth interference, psychosocial and environmental factors, brain transmitters and basal ganglia dysfunction. Attempts have been made to specify the personality traits of bruxers, reported to be greater anxiety or vulnerability to stress; however, this is still controversial. SB subjects were observed to present vigilance-sleepiness and somatic problems. However, they are generally good sleepers. Some authors reported SB during all sleep stages, others observed the majority of bruxe episodes during light sleep and REM and often associated with arousal transients. No abnormalities of the autonomic nervous system could be shown in awake SB subjects. While some studies have shown an association between SB and PLM or breathing disorders, others did not confirm this. There is no specific treatment for SB: each subject has to be individually evaluated and treated. Three management alternatives are used: dental, pharmacological and psychobehavioural.