Changes in upper airway airflow after rapid maxillary expansion considering normal craniofacial development as a...

Area of Science:

• Orthodontics
• Craniofacial Development
• Airway Physiology

Background:

• Rapid maxillary expansion (RME) is known to reduce nasal airflow resistance.
• Medium-term effects of RME on upper airway (UA) airflow characteristics are less understood, particularly considering normal craniofacial development.

Purpose of the Study:

• To evaluate medium-term changes in UA airflow (pressure and velocity) after RME using computer fluid dynamics (CFD).
• To compare these changes in two distinct age-based cohorts: early (6-9 years) and late (11-14 years) expansion groups.

Main Methods:

• Retrospective cohort study of 48 subjects (25 early, 23 late expansion).
• Nasal and pharyngeal anatomy segmented from CBCT scans at baseline (T0) and 12 months post-RME (T1).
• CFD simulations used to analyze UA airflow variables (pressure, velocity) and anatomical measurements.

Main Results:

• Baseline airflow pressure and velocity were higher in the early expansion group.
• Significant improvement in UA airflow parameters was observed in both groups at T1, with greater improvement in the early expansion group.
• Airflow changes correlated negatively with posterior cross-sectional area (CS2) and nasopharynx (NP) size, potentially due to reduced adenotonsillar tissue.

Conclusions:

• Normal craniofacial developmental changes and spontaneous adenotonsillar tissue regression are key factors influencing UA airflow 12 months after RME.
• Findings suggest RME may positively impact UA airflow, with more pronounced effects in younger individuals.
• Results are limited to a retrospective orthodontic sample without obstructive adenotonsillar hypertrophy.