Cone-Beam Computed Tomography Analysis of Facial Asymmetry: Relating Septal Deviations and Uneven Nasal Breathing with Asymmetric Facial Growth
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Cone-Beam Computed Tomography Analysis of Facial Asymmetry: Relating Septal Deviations and Uneven Nasal Breathing with Asymmetric Facial Growth

Abstract

Facial asymmetry can be defined as a mismatch in the shape, location, and size of facial structures bilaterally. While mild asymmetry in human anatomy is considered normal, there are a multitude of factors that can contribute to significant deviations from normal. Understanding the etiologies of facial asymmetry is essential for diagnosing and treating symptoms related to these deviations. Two important areas to consider when assessing facial asymmetry include nasal septum deviations and the internal nasal valve. The long-term goal of this project was to utilize 3-Dimensional analysis of initial CBCT radiographs of orthodontic patients to relate nasal septal deviations and uneven nasal airway, as represented by the internal nasal valve (INV), with asymmetric facial growth. Clinical applications and significance of these findings include analyzing how orthodontic appliances and otolaryngology treatments may contribute to improvement of oral and nasal airways, incorporating internal nasal valve angle and cross-sectional area in nasal airway analysis on CBCT, and ultimately helping patients breathe better and grow symmetrically through an enhanced understanding of the etiologies of nasal and facial asymmetry. We hypothesized that asymmetric nasal airway would affect facial asymmetry and that patients with nasal septum deviation would have significant facial asymmetry related to this deviation. Our specific aims included quantifying the internal nasal valve angle and cross-sectional area using CBCT, identifying degrees of nasal septal deviations, and analyzing facial asymmetry using 3-dimensional CBCT data to relate extraoral asymmetry with nasal asymmetry. This study was a retrospective study evaluating the initial CBCT scans for 25 patients at the UCLA Orthodontics Clinic who were diagnosed with a deviated nasal septum on the UCLA Radiology Report prior to beginning treatment. CBCT files were analyzed using Dolphin Imaging software, and statistical analysis via bivariate correlation was performed to assess significant relationships between nasal and facial asymmetry. Our results demonstrated a significant negative correlation between nasal septum deviation and the internal nasal valve, suggesting that as the angle of septum deviation increased, the internal nasal valve angle and cross-sectional area decreased. However, this study did not necessarily demonstrate the anticipated relationship between nasal and facial asymmetry as seen in other studies. We found a significant correlation between the absolute value of the angle of septum deviation and absolute value of chin deviation at menton. There was also a positive correlation between the angle of the nasal floor, palatal plane, and occlusal plane, however these measurements were not significantly related to the angle of septum deviation. The angle of septum deviation was not significantly correlated with the width of the nasal passage or lateral nasal wall angle, where we would have predicted that if the nasal septum was deviated more to one side, the facial features would also have been significantly deviated to that side. While we elected to pick the most deviated point along the nasal septum to represent the angle of septum deviation, future experimentation should consider assessing the nasal septum deviations along multiple points of the septum, utilization of volumetric measurements to better represent nasal air passage volume and how it is related to facial asymmetry, or a longitudinal study design to better understand the relationship between septal deviations and uneven nasal breathing with asymmetric facial growth.

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