Oropharyngeal changes caused by orthognathic surgery have been a concern because the sleep quality of patients may be enhanced or worsened by these changes. The purpose of this meta-analysis was to identify, review and compare scientific literature about changes in airway in adult patients undergoing orthognathic surgery to correct anteroposterior osseous discrepancies. An electronic search of four databases was carried out up to July 2010, with supplemental hand searching of the references of the retrieved articles. Quality assessment of the included articles was carried out. Data were extracted and a meta-analysis was performed. Heterogeneity was assessed amongst the studies and results were presented in forest plots. 49 studies met the inclusion criteria. Only studies with moderate or high methodological soundness were included in the review. Moderate evidence was found to support a significant decrease in the oropharyngeal airway in mandibular setback surgery, a milder decrease in bimaxillary surgery to correct Class III and an increase in maxillomandibular advancement surgery. Evidence is lacking on airway volume changes after orthognathic surgery.
An important aspect of orthognathic surgery is the effect that skeletal movements and changes in the position of the hyoid bone and tongue may have on the oropharyngeal airway.
Many authors have reported a decrease in airway dimensions after mandibular setback surgery . Others claim that bimaxillary surgery to correct a Class III skeletal deformity (maxillary advancement and mandibular setback) might have less effect on reduction of the pharyngeal airway than mandibular setback surgery alone . Some studies assert that the alterations produced by mandibular advancement (either a surgical one or one obtained using a device) may result in widening of the oropharyngeal airway . Maxillomandibular advancement surgery may also be followed by airway enhancement . Some authors have found no changes in the airway after orthognathic surgery to correct an anteroposterior skeletal discrepancy .
The main concern involving the pharyngeal dimensional changes caused by orthognathic surgery is the sleep quality of the patients. Obstructive sleep apnoea (OSA) has been the subject of numerous studies. It may be cured following a maxillomandibular advancement , may be attenuated by a mandibular advancement and may be worsened or developed after mandibular setback surgery .
The aim of this article was to report the results from a meta-analysis of the scientific literature concerned with changes in the airway in human clinical trials in adult subjects submitted to orthognathic surgery to correct sagittal skeletal deformities.
Material and methods
A specific protocol and research question were developed. The primary objective of this meta-analysis was to evaluate the effect of orthognathic surgery to correct anteroposterior skeletal problems on the oropharyngeal airway. The secondary objective was to compare the effects of different types of orthognathic surgery.
The following criteria were formulated to select articles for inclusion in this review: human clinical trials with a prospective or retrospective design; adults; patients submitted to maxillary or mandibular advancement or setback surgery isolated or combined in any way; measurement of oropharyngeal airway in cephalometric radiographs, magnetic resonance imaging or computed tomography (CT) before and after surgery; articles in English. The exclusion criteria were: case reports, review articles, editorials, or opinions; syndromic, medically compromised or cleft patients; patients submitted to other surgeries not involving the anteroposterior aspect of the maxilla or mandible. Authors of potentially eligible articles written in any language other than English were contacted for a version of the article in English or for the required information.
The electronic databases Virtual Health Library (VHL), Scirus, Ovid and the System for Information on Grey Literature in Europe (SIGLE) were searched. The VHL database includes LILACS, IBECS, MEDLINE, The Cochrane Library, and Scielo databases in its search. Detailed search strategies were developed for each database. Limits were applied only in the search on the Scirus database to restrict the search and reduce the number of articles found. Search strategies, keywords and limits are specified in Table 1 . The searches were performed until July 2010. To locate additional studies, reference lists of all included studies were hand searched. Experts were also contacted to identify unpublished and ongoing studies.
|VHL||“maxillofacial surgery” [Mesh] AND pharynx [Mesh]||1|
|“mandibular advancement” [Mesh] AND pharynx [Mesh]||68|
|“orthognathic surgical procedures” [Mesh] AND pharynx[Mesh]||1|
|Scirus *||orthognathic AND airway||740||humans
|mandibular surgery AND airway||2705||306|
|maxillary surgery AND airway||2318||223|
|Ovid||“orthognathic surgical procedures” AND pharynx||1|
|maxilla AND pharynx||31|
|“mandibular advancement” AND pharynx||29|
|SIGLE||orthognathic AND airway||0|
|mandibular surgery AND airway||1|
|maxillary surgery AND airway||1|