Sleep bruxism in patients with sleep-disordered breathing

The aim was to test the hypothesis of a direct association between sleep-di sordered breathing and sleep bruxism. The frequency of masseter contraction (MC) episodes and rhythmic jaw movements (RJM) was measured in patients wi th mild and moderate obstructive sleep apnoea (OSA). The diagnosis of sleep bruxism was made from a combination of questionnaire, clinical observation and all-night polysomnographic recording which included masseter electromy ography. A total of 21 patients (19 males/two females, mean age 40.0 years +/- 9.2 SD) were randomly selected from a provisional diagnosis of snoring and OSA by a sleep physician. In the patients with mild OSA [n = 11, mean a pnoea hypopnoea index (AHI) = 8.0 +/- 4.1 SD, body mass index (BMI) = 29.1 +/- 5.0], the diagnosis of sleep bruxism was made in six out of 11 patients (54%); similarly, four out of 10 patients (40%) with moderate OSA (n = 10, mean AHI = 34.7 +/- 19.1, BMI = 30.6 +/- 5.0) were identified as bruxists. Although the combination of clinical, subjective estimation and nocturnal electromyographic recording of masseter muscle might provide a more solid b ase for the diagnosis of sleep bruxism, the result is biased by the variati on in the bruxing activity. MC episodes were associated with the terminatio n of apnoea or hypopnoea episodes in only 3.5% of the mild group and 14.4% of the moderate group (p < 0.05). It appears that sleep bruxism is rarely d irectly associated with apnoeic events, but is rather related to the distur bed sleep of OSA patients. (C) 2000 Elsevier Science Ltd. All rights reserv ed.