To evaluate the application of midpalatal cortex osteotomy assisted rapid maxillary expansion for correction of maxillary transverse deficiency in young adults.Fourteen young adult patients with maxillary transverse deficiency were treated with midpalatal cortex osteotomy assisted rapid maxillary expansion. Lateral cephalogram and cone beam CT (CBCT) were taken before and 3 months after treatment. The width of basal bone, arch of maxilla and the torque of anchorage teeth were compared before and after treatment.The width of dental arch of maxilla was increased from 40.54±5.26 mm before treatment to 46.83±5.83 mm after treatment (<0.05) and the width of basal bone was increased from 64.86±4.16 mm to 67.60±4.66 mm (<0.05) at the plane of the maxillary first molars. Accordingly, the width of dental arch of maxilla was increased from 31.92±2.55 mm to 38.65±3.14 mm (<0.05) and the width of basal bone was increased from 43.33±3.70 mm to 45.78±4.57 mm (<0.05) at the plane of first premolar. And the torque of maxillary anchorage teeth were increased (<0.05).Midpalatal cortex osteotomy assisted rapid maxillary expansion is an effective micro-invasive method in expansion of basal bone and arch of maxilla for young adult patients with maxillary transverse deficiency.

Midpalatal corticotomy-assisted rapid maxillary expansion (MCRME) is a minimally invasive treatment of maxillary transverse deficiency (MTD) in young adults. However, the effect of MCRME on respiratory function still needs to be determined. In this study, we evaluated the changes in maxillary morphology and the upper airway following MCRME using computational fluid dynamics (CFD). Twenty patients with MTD (8 males, 12 females; mean age 20.55 years) had cone-beam computed tomography (CBCT) images taken before and after MCRME. The CBCT data were used to construct a three-dimensional (3D) upper airway model. The upper airway flow characteristics were simulated using CFD, and measurements were made based on the CBCT images and CFD. The results showed that the widths of the palatal bone and nasal cavity, and the intermolar width were increased significantly after MCRME. The volume of the nasal cavity and nasopharynx increased significantly, while there were no obvious changes in the volumes of the oropharynx and hypopharynx. CFD simulation of the upper airway showed that the pressure drop and maximum velocity of the upper airway decreased significantly after treatment. Our results suggest that in these young adults with MTD, increasing the maxillary width, upper airway volume, and quantity of airflow by MCRME substantially improved upper airway ventilation.