Effects of rapid maxillary expansion on craniofacial morphology and pharingeal airway in preschool children with OSA

Introduction: Obstructive sleep apnoea syndrome (OSAS) is a co mmon problem in children. It is characterized by a combination of partial airway closure associated with hypoxemia and hypoventilation and intermittent obstructive apnoea that disrupts normal ventilation and sleep. The most co mmon treatment for OSAS in childhood is adenotonsillectomy. Recently, the use of rapid maxillary expansion (RME) as a treatment modality for OSAS has been stressed. The benefit that OSAS has been reported to receive from RME, would suggest that, through the expansion of the maxilla, the function of the nasopharyngeal space would also be positively influenced. The aim of this study was to evaluate the cephalometric effects of RME on the skeletal morphology and airway space in young children suffering from OSA syndrome and to compare the cephalometrics variables, before and one year after RME treatment. Material and methods: A sample of 15 Caucasian children (8 boys and 7 girls), mean age 5.94 ± 1.64 years, was selected from the files of the Dental Clinic, “Sapienza” University of Rome, Sant’Andrea Hospital. All the subjects had a history of disturbed sleep characterized by recurrent apnoeic periods with heavy snoring and were referred by the Paediatric Sleep Disorder Center where they underwent a standard overnight polysomnographic study. All the patients had diagnosis of OSAS with a positive respiratory disturbance index (RDI) (mean 4.47±3.84). The patients were treated with RME and, after the expansion period (10 days approximately), the appliance was held in place for 1.57 ± 0.58 years. Lateral cephalometric films were taken at the start (T0) and at the end (T1) of RME treatment. Results: The maxilla moved forward, as shown by the significant increase in the angles SNA (T0 = 78.33 ± 2.23, T1 = 80.73 ± 1.28, p=0.0008); The sagittal mandibular position (SNB) showed a small increase after treatment, although such difference was only marginally significant (T0 = 74.54 ± 2.79, T1 = 76.00 ± 1.36, p=0.0858); ANB (T0 = 3.83 ± 1.77, T1 = 4.67 ± 1.35, p=0.0279) increased significantly. In the vertical plane the angles ML-NSL (T0 = 38.33 ± 6.18, T1 = 40.20 ± 4.78, p=0.0275) and NL-NSL (T0 = 7.17 ± 2.64, T1 = 9.53 ± 3.20, p=0.0374) were increased. The vertical indices SGo/NMe and NSp/SpMe showed a statistically significant decrease (SGo/NMe: T0 = 63.93± 5.18, T1 = 61.73 ± 4.99, p=0.0368; NSp/SpMe: T0 = 78.80± 7.74, T1 = 74.73 ± 5.82, p=0.0193), revealing an increase of the anterior total and lower face height. The nasopharyngeal airway measurements showed significant increase after treatment (PNSAd²/PNSSo: T0 = 23.39 ± 8.60, T1 = 34.09 ± 7.16, p=0.0064; PNSAd¹/PNSBa: T0 = 30.21 ± 11.45, T1 = 36.91 ± 11.30, p=0.0171) and reduction of lymphoid tissue in Waldayer’s ring (Ad²So/PNSSo: T0 = 73.19 ± 8.79, T1 = 65.67 ± 7.45, p=0.0015; Ad¹Ba/PNSBa: T0 = 70.27 ± 10.67, T1 = 60.50 ± 12.91, p=0.0070). These results suggest that RME may be useful in the treatment of young children with OSAS.