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Association Between the Extraction of Second Premolars and Airway Volume
abstract
This abstract is available on the publisher's site.
Access this abstract now Full Text Available for ClinicalKey SubscribersINTRODUCTION
The extraction of second premolars and associated changes in the volume of the airway have not been previously explored. This retrospective study aimed to compare the volumetric changes of the airway preorthodontic and postorthodontic treatment in relevant extraction and control samples and to identify variables that may influence the outcome.
METHODS
Cone-beam computed radiography scans of 54 patients with second premolar extraction and 59 nonextraction patients treated in a private orthodontic practice were matched for crowding. The average age for both samples was 15 years. The images were individually landmarked and measured by applying volumetric, linear, and angular parameters. The results were analyzed using repeated measures, such as variance analysis, correlation testing, and regression statistical analyses.
RESULTS
There was a statistically significant increase in the airway volume for both groups (P <0.05). The difference in increase between the groups was not statistically significant. Seven variables demonstrated a collectively significant effect on changes to airway volume (F[7,112] = 38.48; P <0.001; r2 = 0.701), with 70% of the variation predicted by the variables. Multiple regression analyses indicated that changes to the area of minimum constriction (B = 32.45; t = 11.95; P <0.001) and changes to airway length (B = 94.75; t = 7.79; P <0.001) had a statistically significant effect on airway volume.
CONCLUSIONS
The volume of the airway increased in both the extraction and nonextraction samples. The biggest contributors to the increase were an increase in airway length and an increase in the area of minimum constriction, which likely occurred as a result of natural growth.
Additional Info
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The orthodontic extraction of second premolars: The influence on airway volume
Am J Orthod Dentofacial Orthop 2024 Apr 26;[EPub Ahead of Print], M Mladenovic, S Freezer, C Dreyer, MJ MeadeFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
Extraction and nonextraction orthodontics have long been presented as an oscillating controversy from one decade to the next several decades and were initially promulgated by Tweed and Begg in managing dental crowding. The issues have been the potential dental comorbidities of temporomandibular disorders, retrusive profiles, and compromised facial esthetics. More recently, medical comorbidities have emerged as a potential consequence of increased awareness of the sleep-disordered breathing spectrum, including obstructive sleep apnea syndrome (OSAS) presenting as an end-stage diagnosis. The argument for bicuspid extractions causing or contributing to the risk of acquiring such a diagnosis has heated up in recent years. The potential retractive effect of bicuspid extractions in addressing dental crowding has raised the question of a possible adverse impact on the functional space that defines the airway.
This study sought to investigate possible changes in the airway volume by comparing cohorts of growing patients who underwent extraction versus nonextraction orthodontics measured via cone-beam CT (CBCT) radiographic analysis in a private practice setting between 2015 and 2021. The results of this study showed a statistically significant increase in the airway volume in both the extraction and nonextraction groups, with little difference between the two groups; therefore, the null hypothesis that the airway volume would not decrease because of the extraction protocol was not rejected.
There were a few weaknesses to consider in the study design and the premise of the importance of airway volume in acquiring OSAS. A recent study by Coppelson et al in 2023 concluded that alterations in the head posture significantly affected the minimum cross-sectional area of the upper airway on routine CBCT studies,1 which would have a significant effect on the airway volume assessment. Moreover, it is not the volume of the airway that poses a significant risk factor for OSAS but rather the constriction or Starling resistor in the airway system, with the nasal liminal valves and velopharynx at the oropharyngeal junction being the most common areas of resistance.
This study also found that the increase in the airway length was the biggest contributing factor to the increase in the airway volume. It is known that increasing the length of the airway potentially increases the instability of the airway; however, the sample studied was growing patients, which further posed a confounding variable in assessing the relationship between bicuspid extractions and changes in the airway volume. The association of airway volume with the risk of OSAS is weak, considering the pathophysiology of the condition. Perhaps, a better question to ask regarding extraction orthodontics to address dental crowding may be why there was dental crowding to begin with, now knowing that genetics cannot fully explain the increased incidence of malocclusion worldwide.2
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