No abstract

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.

SUMMAR Y Sleep bruxism (SB) subjects show a higher incidence of rhythmic masticatory muscle activity (RMMA) than control subjects. RMMA is associated with sleep microarousals. 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 £ 0.02). The cross-correlation plot for microarousal index showed positive association from 4 min preceding SB onset in the moderate to high SB subjects (P £ 0.06). The cross-correlation plot revealed that SWA decreases following SB onset (P £ 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 £ 0.03). In moderate to severe SB subjects, a clear increase in sympathetic activity precedes SB onset.