Sleep bruxism associated with obstructive sleep apnoea syndrome - A pilot study using a new portable device.

Sleep bruxism (SB) and obstructive sleep apnoea syndrome (OSAS) share common pathophysiologic pathways. We aimed to study the presence and relationship of SB in a OSAS population. Patients referred with OSAS suspicion and concomitant SB complains were evaluated using a specific questionnaire, orofacial evaluation and cardio-respiratory polygraphy that could also monitor audio and EMG of the masseter muscles. From 11 patients studied 9 had OSAS. 55.6% were male, mean age was 46.3±11.3 years, and apnea hypopnea index of 11.1±5.7/h. Through specific questionnaire 55.6% had SB criteria. Orofacial examination (only feasible in 3) confirmed tooth wear in all. 77.8% had polygraphic SB criteria (SB index>2/h). Mean SB index was 5.12±3.6/h, phasic events predominated (72.7%). Concerning tooth grinding episodes, we found a mean of 10.7±9.2 per night. All OSAS patients except two (77.8%) had more than two audible tooth-grinding episodes. These two patients were the ones with the lowest SB index (1.0 and 1.4 per hour). Only in one patient could we not detect tooth grinding episodes. There was a statistically significant positive correlation between tooth grinding episodes and SB index and phasic event index (R=0.755, p=0.019 and R=0.737, p=0.023 respectively, Pearson correlation). Mean apnoea to bruxism index was 0.4/h, meaning that only a minority of SB events were not secondary to OSAS. We could not find any significant correlation between AHI and bruxism index or phasic bruxism index (R=-0.632 and R=-0.611, p>0.05, Pearson correlation). This pilot study shows that SB is a very common phenomenon in a group of mild OSAS patients, probably being secondary to it in the majority of cases. The new portable device used may add diagnostic accuracy and help to tailor therapy in this setting.