Sleep Bruxism as a Protective Factor in the Mild and Moderate Obstructive Sleep Apnea: A Polysomnographic Study

The protective properties of sleep bruxism (SB) for obstructive sleep apnea (OSA) are often suggested in the literature. The main objective of the present study is to assess the alleged protective effects of SB on the duration of respiratory events and blood saturation in OSA patients. The study involved data from 241 subjects with mild and moderate OSA who underwent polysomnography, which was evaluated according to American Academy of Sleep Medicine guidelines. Two cut-off points for SB diagnosis were established-bruxism episodes index (BEI) = 2 and BEI = 4. Out of the 241 patients, 66 subjects did not have SB (BEI < 2), while 175 were bruxers (BEI ≥ 2) and 97 of them had severe bruxism (BEI ≥ 4). SB patients had a significantly increased duration of hypopnea and apnea + hypopnea in both BEI ≥ 2 (25.88 vs. 23.28, p = 0.001 and 24.04 vs. 21.97, p = 0.004, respectively) and BEI ≥ 4 (26.17 vs. 24.49, p = 0.038 and 24.30 vs. 22.92, p = 0.040, respectively) groups. The oxygen desaturation index (47.64 vs. 51.10, p = 0.004) was decreased in BEI ≥ 2 subjects. Snore % was decreased in the BEI ≥ 4 group (21.22 vs. 26.43, p = 0.039). Average pulse was lower in the BEI ≥ 2 group (60.58 vs. 64.30, p = 0.0009). These results contradict the hypothesis that SB episodes shorten the apnea-hypopnea events in OSA patients. Protective SB properties might be limited to milder airway obstruction or might diminish over time. The relationship between SB and OSA is complex and needs further extensive research.