Avaliação tridimensional da via aérea superior após cirurgia ortognática com rotação anti-horária do complexo maxilomandibular

Abstract

Airway dimensions are determined by anatomical structures such as soft tissues, musculature and craniofacial bones related to the pharynx. Anatomical alterations of those structures can make the superior airway space narrower thus interfering in its functional pattern and turns out to be an important etiological factor in a disorder known as Obstructive Sleep Apnea Syndrome (OSAS), often seen in Class II facial pattern patients. Orthognathic surgery (OS), used to correct dental-skeletal deformities, has turned out to be efficient in the treatment of serious OSAS cases when compared to other procedures such as uvulopalatopharyngoplasty, suspension of the hyoid and advancement of the genioglossus. However, it can have a positive or negative effect on patients\' sleep quality. Patients with Class III dental skeletal deformities show a decrease in the superior airway space (SAS) after undergoing OS for mandibles setback, although it is not often dealt with in the literature. Many studies measuring posterior airway changes use lateral cephalometries to analyze such alterations, but those have limitations as they use a bidimensional method (2D) to measure tridimensional structures (3D). Computer tomographies make it possible to reconstruct 3D structures and enable a more accurate measurement to be done. The combination of both assessment techniques, 2D and 3D, contribute to standardization, surgical planning, and to the obtainment of more precise results. The aim of this retrospective study was to evaluate SAS alterations in Class II patients undergoing OS with counterclockwise rotation of Maxillo Mandibular Complex (MMC) using Cone-beam computer tomography (CBCT). The computer tomographies images obtained from a DICOM file (Digital Imaging and Comunications in Medicine) were exported into the sofware program Dolphin Imaging 11.5 (Dolphin Imaging and Management Solutions, Chatsworth,CA,USA) to do 3D measurement of surface area (SA), minimal axial area (MAA) and posterior air space volume (VOL). Twenty-three patients with a history of respiratory disorders were assessed, 15 female and 8 male, with average age of 34,04 years (16 to 64 years), subjected to computer tomographies at two intervals: T1 (pre-operative) and T2 (six month minimum post-operative). The data obtained were tabulated and statistically analyzed. A t-Student and Wilcoxon paired test was used and the result obtained was statistically significant (p<0.05) regarding an increase in SAS in patients undergoing OS with counterclockwise rotation of the MMC in this study.