Effects of Rapid Maxillary Expansion on Urinary Leukotriene E4 and Serum C-Reactive Protein Levels in Children With Obstructive Sleep Apnea and Maxillary Restriction: A Prospective Longitudinal Study.

Rapid maxillary expansion (RME) has been advocated as a viable treatment option in pediatric obstructive sleep apnea (OSA) due to its favorable effect in enhancing upper airway and respiratory parameters. This study aimed to evaluate the effect of RME on urine leukotriene E4 (uLTE4) and serum C-reactive protein (CRP) levels in OSA children with maxillary constriction and determine the association between alterations in uLTE4 and serum CRP levels and changes in dentoalveolar and respiratory parameters. This prospective longitudinal study comprised 47 children, aged 8-12 years, with polysomnography-proven OSA and maxillary constriction, who were treated with the RME appliance and matched with corresponding controls. uLTE4 and serum CRP levels were measured before and after treatment. A second standard overnight polysomnography (PSG) was conducted to assess changes in respiratory parameters. Inter-molar width increased by 5.1 mm (p < 0.001). The RME resulted in a significant increase in the facial height and inferior dislocation of the maxilla (p < 0.05). Respiratory parameters changed significantly in the study group; sleep efficiency increased by 3.41% (p = 0.036), minimum oxygen saturation increased by 5.32% (p < 0.001), arousal index decreased by 7.46 events/h (p < 0.001), and apnea-hypopnea index (AHI) decreased by 3.53 events/h (p < 0.001). There was no significant difference in uLTE4 and serum CRP levels in the study or control group (p > 0.05). There was no association between the AHI and changes in uLTE4 and serum CRP levels after treatment (p > 0.05); however, a positive association was found with the intermolar width (p = 0.019). The treatment of pediatric OSA with the RME appliance did not affect uLTE4 or serum CRP levels, despite significant improvements in dentoalveolar features and respiratory sleep parameters.