The effect of rapid palatal expansion on sleep bruxism in children.

Background: Sleep bruxism (SB) is a movement described as an involuntary mastication movement during sleep, also defined as rhythmic masticatory muscle activity (RMMA). It is observed in 2-40 % of the pediatric population. A link was suggested between respiratory events and RMMA. Rapid palatal expansion (RPE) is an effective orthopedic treatment for correcting maxillary transverse deficiency and sleep-disordered breathing (SDB) in children. The aim was to evaluate the possible reduction of SB after rapid palatal expansion (RPE) therapy.

Methods: A total of 32 patients (8-14 years old; 22 girls and 10 boys) received an orthodontic treatment for transverse maxillary deficiency (5 mm or more) at the orthodontics department of the Université de Montréal. They underwent an ambulatory polysomnography (PSG) before, after expansion with the expander, and at the end of the study without the expander. They were classified into three subgroups based on sleep electromyography (EMG) data.

Results: Total sleep time and stage NREM 3 presented significant differences between the types of appliances. Moreover, there was a time effect observed for total sleep time, sleep cycles, stage NREM 2, and stage REM, while only a trend suggested for stage NREM 3. Significant differences were observed between subgroups for both RMMA episodes and burst indexes, similarly, for the oxygen desaturation index (ODI). A total of 50 % of the patients were classified as responders when RMMA episodes index decreased by more than 25 % when comparing treatment efficacy at baseline night.

Conclusion: Most bruxers (65 %) reduced their RMMA episode index after expansion, but sleep and respiratory variables remained unchanged.