Three-dimensional effects of maxillary protraction on Pharyngeal Airway

Abstract

Introduction: patients with maxillary deficiency can exhibit reduced pharyngeal airway dimensions which can negatively affect the breathing efficiency of such cases. Objective: the purpose of this study was to measure the changes in pharyngeal airway dimensions induced by maxillary protraction using facemask in a group of growing skeletal class III patients. Materials and methods: 20 growing patients with ages ranging between 8-11 years and CVMI stages 1& 2 were included in the study. Patients were diagnosed of skeletal class III malocclusion due to maxillary deficiency. All patients received facemask therapy as a treatment. CBCT scans were taken before the beginning of the treatment and by the end. The nasopharyngeal, oropharyngeal airway volumes and the minimum constricted area were measured using Dolphin software on CBCT scans. Results: All the measured airway dimensions increased significantly after facemask therapy. Conclusion: maxillary protraction induced by facemask treatment in young children was able to effect significant changes in the measured airway dimensions. (72) Mai H. Aboulfotouh, et al. E.D.J. Vol. 67, No. 1 are mainly due to maxillary hypoplasia alone or maxillary hypoplasia coupled with mandibular prognathism(1,2). Enlow (3) described the typical Class III individual as having a middle cranial fossa that is rotated in a backward and upward manner, resulting in the nasomaxillary complex being in a more retrusive position. Also forward rotation of the ramus is often encountered together with a vertically short nasal region. (1–5). Awareness of maxillary deficiency as all or part of the class III structural etiology, has led to the increased popularity of maxillary protraction appliances among which the facemask or the reverse pull head gear plays the leading role(6,7). Protraction facemask has gained wide popularity over the past decades, as it successfully demonstrated a significant orthopedic effect on the maxilla by continuous protraction and strain at the craniomaxillary sutures. The aim of these orthopedic approaches is to provide a more favorable environment for normal growth as well as an improvement in the occlusal relationship(8). Several studies demonstrated the skeletal and dentoalveolar effects of maxillary protraction appliances, which were mainly the stimulation of the forward growth of the maxilla, redirection of the growth of the mandible into a more downward and backward rotation. This is also coupled with anterior and upward rotation of the palatal plane, protrusion of the upper incisors, and retrusion of the lower incisors(9–11). While the dental and skeletal effects of the protraction facemask have been elaborated in many studies, its effect on the patients’ airway dimensions was not investigated as much. Adequate pharyngeal size is important to guarantee that the patient gets a well sleep. Few studies highlighted the positive effect that maxillary protraction can induce on increasing the pharyngeal airway (12–16). However, in all the studies, 2dimensional lateral cephalograms were used for measuring the airway size and hence only the antero-posterior dimension of the airway was measured rather than the total volume of this space. Thus, the purpose of this study was to investigate the effect of maxillary protraction facemask treatment on the airway dimensions using cone beam computed tomography in a group of growing children. MATERIALS AND METHODS This study was approved by the Research Ethics Committee, Faculty of Dentistry, Cairo University. All patients were informed about the study procedure and written informed consents were obtained from their parents.