Findings on sleep bruxism (SB) in patients with obstructive sleep apnea syndrome (OSAS) are controversial, and some of these findings have relied on in-laboratory polysomnography (PSG). We aimed to identify the factors associated with SB episodes in 100 patients with OSAS using in-laboratory PSG records. Subjects with OSAS were divided into those with and without SB episodes. We analyzed the differences in patient characteristics and PSG indices. Age, gender, height, weight, body mass index, neck, waist, and hip circumferences, and the rates of hypertension and diabetes mellitus were not significantly different between the two groups. A greater proportion of stage N2 sleep in the total sleep time, longer total sleep time, longer sleep time in a supine position, shorter sleep time in a nonsupine position, lower apnea–hypopnea index (AHI), lower AHI regardless of sleeping position, lower AHI during nonrapid eye movement sleep, and higher mean oxygen saturation level were associated with SB episodes in patients with OSAS. Among these factors, longer sleep time in a supine position remained a statistically significant factor in multivariate analysis. We conclude that longer sleep time in a supine position (especially >280 min) might be associated with SB episodes in patients with OSAS.

Stress or pressure induced by the use of a mandibular advancement device (MAD) to treat sleep-disordered breathing can cause side effects including occlusal changes, pain, and discomfort. In this paper, we describe and use finite element (FE) analysis to evaluate a novel MAD that can reduce the stress and side effects associated with these devices. The MAD includes a protruding part that enables rostral movement of the lower tray, providing a wider upper airway and a supporting shield that helps uniformly distribute the concentrated stress. After assembling the three-dimensional model for the MAD and the upper oral structures, a designated force was applied to evaluate the stress distributions of a conventional MAD and the proposed design. FE analysis showed that the stress applied to the upper front teeth and the gingival area near the upper incisors differed between the newly developed and conventional MAD. Concentrated stress was relieved by inserting such a shield, helping to distribute the stress from the front teeth to the gingival area. Our proposed MAD reduced the concentrated stress on the front teeth by distributing it over the gingival area.

No abstract