Oropharyngeal Airway Volume Following Orthodontic Treatment: Premolar Extraction Versus Non-extraction

Introduction: Concern has been raised that premolar extraction reduces arch length and diminishes space for the tongue, thus forcing the tongue to be retro-positioned. There is speculation that this retro-position of the tongue reduces pharyngeal space leading to breathing problems, notably obstructive sleep apnea. There is little evidence that retracting teeth into extraction spaces changes airway volume. This study evaluated oropharyngeal dimensions following four premolar extractions and subsequent orthodontic therapy to determine whether there was a change in airway volume. Methods: 154 healthy patients were assessed from a private practice database of preand post-treatment CBCT images (64 patients had 4 premolars extracted and 90 were treated non-extraction). A total of 54 cephalometric, areal, and volumetric variables were studied from the DICOM files using Dolphin 11.5. Two-way ANCOVA tests were used to assess for in-treatment changes; patient’s sex and treatment (extraction, nonextraction) were fixed effects, with age as the covariate to account for patient growth. Results: Just one of eight pharyngeal variables differed between treatments (Psp-Phw, upper pharyngeal depth); this difference persisted from the start through the end of treatment, and it was larger in the extraction sample. No pharyngeal treatment change differed significantly between the extraction and non-extraction groups. Conclusion: Extraction of premolars did not discernibly affect oropharyngeal volume in adolescents.