Three‐dimensional pharyngeal airway changes in orthodontic patients treated with and without extractions

Abstract

Facial asymmetry index in normal young adults Orthod Craniofac Res 2013; 16: 97-104. Abstract Objectives-To differentiate a symmetric face from an asymmetric face by analyzing a three-dimensional (3D) facial image and plotting the asymmetry index (AI) on a facial symmetry diagram. Setting and Sample Population-Sixty healthy Chinese adults (30 men and 30 women, mean age: 27.7 + 4.9 years old) without any craniofacial deformity were recruited on a voluntary basis from a medical center. Material and Methods-A 3D facial image of each participant was captured by a GENEX 3D FACE CAM system. Sixteen facial landmarks, as defined by Farkas, were selected on each 3D facial image. The AI was calculated for each landmark. Results-The norm for the AI varied from 0.76 to 2.82. The landmarks located on the upper face had a smaller AI than the landmarks located on the lower face. A facial symmetry diagram was designed according to the mean, one standard deviation, and 2 standard deviations of AI for each landmark. Conclusions-The 3D facial asymmetry can be documented with AI. The landmarks located on the upper face had a smaller AI than the landmarks located on the lower face. The facial symmetry diagram can identify efficiently the location of asymmetry on a face.

Effects of bicuspid extractions and incisor retraction on upper airway of Asian adults and late adolescents: A systematic review

“…Decrease in airway space and changes in hyoid bone position after orthodontic extractions have been reported. Conversely, other studies have found no change in airway space and hyoid position after orthodontic extractions. The lack of consensus could be attributed to differences in patient age and extraction indications .…”

Reviewing the Evidence: Do Orthodontic Premolar Extractions Directly Cause Obstructive Sleep Apnea?

“…On the contrary, efforts lean towards no relationship between the extraction of four premolars and the incidence of OSA. It should be noted though, that in a select few studies, the change in airway space following orthodontic extraction of four premolars differed according to the severity of the dental crowding, the amount of protrusion of the anterior dentition and the variety of the mechanics utilized to close the extraction spaces [6,[9][10][11][12][13][14].…”

Evidence Supports No Relationship between Obstructive Sleep Apnea and Premolar Extraction: An Electronic Health Records Review

“…[8][9][10][11][12][13][14][15] Other studies suggest that changes in airway volume associated with orthognathic surgery or orthodontic treatment may reduce the airway space and contribute to OSA. [16][17][18][19][20][21][22][23] One proposed mechanism is that orthodontic treatment with premolar (bicuspid) extractions can decrease the airway space, due to retraction of incisors, and therefore possibly lead to OSA. Studies examining the change in airway space after extractions for orthodontic treatment have produced varying results.…”

“…authors [18][19][20] found that orthodontic treatment with premolar extraction does not decrease the intraoral airway space regardless of the amount of incisor retraction achieved. Others [21][22][23] found a decrease in the airway volume, which depended upon the type of space closure utilized during orthodontic treatment.…”

“…The amount of change in airway space following orthodontic treatment involving the extraction of four premolars varies according to the amount of crowding and/or protrusion of the teeth and the type of mechanics used to close the spaces. [16][17][18][19][20][21][22][23] One limitation of these studies is that, although they measured changes in airway space, none examined this relationship to OSA. Other variables that should be considered but were not available include skeletal characteristics of the subjects [8][9][10][11][12][13][14][15] and which individuals had or had not undergone orthodontic treatment.…”