Effect of rapid maxillary expansion on monosymptomatic primary nocturnal enuresis

Objective: To evaluate the effects of rapid maxillary expansion (RME) on nocturnal enuresis (NE) related to the nasal airway, nasal breathing, and plasma osmolality (as an indicator for antidiuretic hormone). Materials and Methods: Nineteen patients with monosymptomatic primary NE, aged 6-15 years, were treated with RME for 10-15 days. To exclude a placebo effect of the RME appliance, seven patients were first treated with a passive appliance. Computed tomography of nasal cavity, rhinomanometric, and plasma osmolality measurements were made 2-3 days before and 2-3 months after the RME period. RME effects on NE were followed for three more years. Results: Two to three months after the expansion there were significant improvements in the breathing function and a decrease in the plasma osmolality. NE decreased significantly in all patients after the RME period, and all patients showed full dryness after 3 years. Conclusions: This study demonstrates that RME causes complete dryness in all patients, with significant effects on pathophysiological mechanisms related to NE.