Evaluating the effect of midpalatal corticotomy-assisted rapid maxillary expansion on the upper airway in young adults using computational fluid dynamics

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.

Surgically assisted rapid palatal expansion in class III malocclusion: Our experience

INTRODUCTION

Maxillary transverse deficiency (MTD) is a common facial disharmony that may need surgical assisted rapid palatal expansion (SARPE). The aim of this study was to present our SARPE technique and to report about our experience.

MATERIEL AND METHOD

Medical records of all class III patients who underwent SARPE in our department from 2010 to 2015 and for whom a follow-up of at least 1year was available, were included in a retrospective study. The technique consisted, after short orthodontic preparation allowing for divergence of the upper central incisors, in a complete Le Fort I osteotomy without down fracture, and medial sagittal submucosal separation of the hard palate under general anesthesia in an inpatient procedure. Teeth-supported distracters were sealed preoperatively while bone-supported devices were inserted peroperatively. Activation of the distracter was allowed from day 2 at the rate of 2×0.25 per day during 4days and 2×0.5mm per day the following days. Distracters were left in place for about 4months. Orthodontic treatment resumption was allowed from the second month. The initial malocclusion, the amount and type (parallel or angular) of distraction that was needed, the type of distracter used, the amount of distraction obtained, the per- and postoperative complications and the clinical stability of the end result were analyzed.

RESULTS

The records of 23 patients (18 women, 5 men - average age: 25.4years, extremes: 16-55years) could be included. MTD was isolated in 6 cases, associated with a maxillary retrognathism in 5 cases, with a mandibular prognathism in 6 cases, and with both in 6 cases. The average amount of distraction needed was 7.2mm (range: 4-12), parallel in 20 cases and angular in 3 cases. The distracters were bone-supported (Rapid Palatal Expander^®, KLS Martin Group, Tuttlingen, Germany) in 3 patients and custom-made tooth-supported in 20 patients. The average amount of distraction obtained at the level of the distracter cylinder was 7.7mm (range: 5-13). We noted 2 cases of palatal fibromucosa perforations, 1 case of posterior excess of distraction, 1 case of nasal septum deviation, 1 case of iatrogenic necrosis of tooth No.°11, 1 case of naso-genial sulcus hematoma, 1 case of intraoperative mobility of tooth No.°21, 5 cases of asymmetric distraction. Seventeen patients needed a second orthognathic procedure and 22 had stable Class I occlusion after removal of appliances at 18 months follow-up on average.

DISCUSSION

SARPE is a quite safe procedure that allows for transverse coordination without dental extraction. Transverse discrepancies greater than 4mm are for us clear indications for SARPE. When a sagittal discrepancy is associated, we prefer performing SARPE first and correcting the sagittal plane in a second operation. The recent development of Le Fort I sliding osteosynthesis plates opens the way to one time correction and the development of double-action distracters fitted out with 2 cylinders will be helpful for performing angular distractions.