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

A Commentary On: 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 .

Design: Retrospective study and untreated matched controls.

Data Source: PubMed, journals.plos.org, researchgate.net, Google Scholar.

Study Selection: 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.

Inclusion Criteria: 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.

Exclusion Criteria: 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.

Results: 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.

Study Conclusions: 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.