Unmasking the hidden risks: clinical implications of 4 premolar extraction orthodontics on health and upper airway...

Zhang J, Chen G, Li W, Xu T, Gao X Upper airway changes after orthodontic extraction treatment in adults: a preliminary study using cone beam computed tomography. PLoS ONE 2015; https://doi.org/10.1371/journal.pone.0143233 .

Retrospective study and untreated matched controls.

PubMed, journals.plos.org, researchgate.net, Google Scholar.

This retrospective study enrolled 18 adults with Class II and hyperdivergent skeletal malocclusion (5 males and 13 females, 24.1 ± 3.8 years of age, BMI 20.33 ± 1.77 kg/m2). And 18 untreated controls were matched 1:1 with the treated patients for age, sex, BMI, and skeletal pattern.

Age >18 years; sagittal Class II (ANB > 4.7°) and vertical hyperdivergent (MP/SN > 37.7°) skeletal pattern; convex profile evaluated by E line; no missing teeth except for the third molars; orthodontic camouflage treatment with extraction of four premolars and maximum anchorage using mini-screws; and available CBCT data both before and after treatment.

Body mass index (BMI) > 25 kg/m2. Rapid maxillary expansion, protraction facemask therapy, extra-oral force to push molars distally, functional appliances, and orthognathic surgery. History of cleft lip or palate. Hyperplasia of tonsils or adenoids or history of tonsillectomy/adenoidectomy. Snoring or other sleep disorders.

Four premolar extraction, upper incisors retracted 7.87 mm, lower incisors retracted 6.10 mm. The cross-sectional area of the upper airway was not changed, but the sagittal dimension between the soft palate and the posterior pharyngeal wall were significantly decreased.

The study reported that its null hypothesis was not rejected, with no significant difference in the airway size and significant compression of the sagittal posterior airway.