Sleep Bruxism: Dual Role in Obstructive Sleep Apnoea Syndrome

<bold>Background:</bold> Obstructive Sleep Apnoea Syndrome (OSAS) is characterised by complete/partial collapse of the upper airway during sleep and excessive daytime sleepiness (EDS). Sleep bruxism (SB) is a common sleep-related motor disorder, that coexcists with OSAS. SB is characterised by involuntary grinding and clenching of the teeth during sleep, accompanied by tooth wear, jaw muscle pain, fatigue and headache. <bold>Objective:</bold> To investigate the relationship between SB and OSAS characteristics. <bold>Methods:</bold> This cross-sectional study included patients who underwent full nocturnal polysomnography and were clinically assessed for SB. Group comparisons were based on the presence of OSAS and SB. Apnoea Hypopnoea Index (AHI), percentage-of-time-with SpO2<90% (t%SpO2<90%) and EDS according to Epworth Sleepiness Scale were evaluated, using Mann-Whitney-U-test. Linear regression models were used to calculate correlation coefficients (coef) of known confounders, age, sex and body mass index (BMI). The significance level was set at 0.05. <bold>Results:</bold> A total of 345 patients (age: 55.8±13.5 years, 68.1% male and BMI: 34.3±7.3), were examined.13.6% were sleep bruxers. SB showed an independent strong positive effect on EDS (coef:1.439;pValue=0.012) and a weak negative effect on AHI and t%SpO2<90% (coef:-5.545;pValue=0.183, coef:-3.289;pValue=0.234 respectively), controlling for known confounders. <bold>Conclusions:</bold> Patients with OSAS and SB present higher index of daytime sleepiness and tend to have reduced OSAS severity indices compared to non-bruxers. SB should not be underestimated and more future studies could clarify the impact of this sleep behavior in patients with breathing sleep disorders.