This retrospective study evaluated changes in the pharyngeal part of the upper airway in patients with restricted and normal airways treated with aligners. The Obstructive Sleep Apnea (OSA) is a common sleep disorder caused by nocturnal collapse of the upper respiratory tract. It is accompanied by hypoxia, fragmented sleep, blood pressure fluctuations, and sympathetic nervous system activity.
“Apnea can be treated with aligners, dental camouflage, orthognathic surgery, and a 3D printed distalizer.”
Understanding the biomechanics of the aligner technique is the key to success. This study compared the clinical effects of aligner therapy on upper airway morphology in patients with stenosis before treatment and in patients without stenosis.
Study and hypothesis to apply transparent aligners
This study compared the clinical effects of aligner therapy on upper airway morphology in patients with stenosis before treatment and in patients without stenosis.
The working hypothesis was that if the pre-treatment airway constriction is the result of disturbed occlusion and/or incorrect intermaxillary relationship, an orthodontic correction would result in a characteristic improvement. The lower limit of the epiglottis was defined by a study by dos Santos et al. to correlate airway volume and the location of the zone of maximum constriction in different facial dental deformities. Orthodontic treatment has a negligible effect on upper airway volume in adults, while Wang et al. found that the size of the pharyngeal airway became narrower after treatment.
Group selection and clinical evaluation consisted of non-growing adult patients with restricted airways identified on 3D CBCT analysis. The first group consisted of fifty-five patients with airway constipation, while the second group consisted of thirty-one patients with adequate airways without significant difficulties or abnormalities in their breathing pattern.
Study of groups with and without OSA for the use of transparent aligners
group A consisted of people who had upper airway constriction before receiving clear alignment therapy. (Invisalign).
group B represented a pool of patients treated from baseline with no identified airway constriction, based on 3D CBCT analysis.
Data collected from both the restricted airway and control groups were collected in a complete Microsoft Excel file, with airway volume within defined limits, the minimum area of the most restricted section, and the level of maximum constriction before and after treatment.
The most important details are the total airway volume, the minimum zone of constriction, and the level of airway contraction based on the degree of the cervical vertebrae. The most important details are the changes in airway volume, the minimum surface area, and the airway surface area at the level of greatest constriction.
The Wilcoxon Signed Ranks test showed 36 positive and 19 negative slots from 55 patients, indicating that the minimum area at the end of treatment was greater in 36 cases.
Results of the study for the use of aligners
This study confirmed the hypothesis that improvement in occlusion and/or jaw relationship results in improved airway clearance, especially in cases where anterior constriction was present. CBCT imaging is not the only diagnostic tool for obstructive sleep apnea, and special sleep studies, oximetry, and other measurements are necessary to diagnose OSA.
This study found that pharyngeal airway spacing differs significantly between men and women, and that airway anatomical changes measured by CBCT with surgical and dental appliance treatment are associated with treatment outcomes. Limitations include patient selection and large clinical heterogeneity.
Revealing results
The volume of the upper airways of the patients treated with aligners had a change.
Pre- and post-CBCT evaluations of the alignment interventions revealed a change in the position of the tongue and its relationship to the incisors and palate in an average of 62.2% cases.
