Midpalatal suture maturation in 15- to 35-year-olds: morphological assessment in the coronal plane using CBCT-an exploratory study

Changes in upper airway airflow after rapid maxillary expansion considering normal craniofacial development as a factor: a retrospective study using computer fluid dynamics

Background/Objectives

Evidence suggests nasal airflow resistance reduces after rapid maxillary expansion (RME). However, the medium-term effects of RME on upper airway (UA) airflow characteristics when normal craniofacial development is considered are still unclear. This retrospective cohort study used computer fluid dynamics (CFD) to evaluate the medium-term changes in the UA airflow (pressure and velocity) after RME in two distinct age-based cohorts.

Materials/Methods

The study included 48 subjects who underwent RME divided into two cohorts: a 6−9-year-old group (EEG group: early expansion group − 25 subjects) and an 11−14-year-old group (LEG group: late expansion group − 23 subjects). The nasal cavity and pharyngeal anatomy were segmented from Cone-beam computed tomography reconstructions taken before RME (T0) and 12 after RME (T1). The two UA airflow variables (pressure and velocity) were simulated using CFD. The maxillary expansion (PW) amount, two cross-sectional area measurements (CS1 = anterior cross-section and CS2 = posterior cross-section), and four UAs’ subregions (NC = nasal cavity, PAtotal = pharyngeal airway, NP = nasopharynx, VP = velopharynx, and OP = Oropharynx) were also considered. All data were statistically analyzed.

Results

At the baseline, the airflow pressure, velocity, and noted obstructions were significantly higher in the EEG compared to LEG. At T1, there was a significant improvement in the median airway parameters in both groups, which was remarkably greater in the EEG. A significant negative correlation was found between pressure/velocity and both CS2 and NP. According to the CFD plots, the airflow pressure and velocity changes could be attributed to the reduction of the adenotonsillar tissues’ sizes, which were remarkably more marked in the EEG.

Limitations

The results of this study cannot be generalized since they referred to a retrospective orthodontic sample without obstructive adenotonsillar hypertrophy.

Conclusions/Implications

Twelve months after RME, normal craniofacial developmental changes and spontaneous adenotonsillar tissues volume regression could represent the most significant factors influencing UA airflow changes.

Medium-term effects of rapid maxillary expansion on nasal cavity and pharyngeal airway volumes considering age as a factor: A retrospective study

OBJECTIVES

The medium-term effects of rapid maxillary expansion (RME) on nasal cavity (NC) and upper airway (UA) dimensions based on chronological age are still unclear. This retrospective study evaluated the medium-term changes occurring in the NC and pharyngeal airways (PA) after RME in two distinct age-based cohorts of patients.

METHODS

This retrospective study included 48 subjects who underwent RME grouped in two cohorts: a 6-9-year-old group (EEG group: early expansion group - 25 subjects) and an 11-14-year-old group (LEG group: late expansion group - 23 subjects). NC and PA volumes were analyzed from CBCT imaging segmentation before RME (T0) and twelve months after RME (T1). The amount of maxillary expansion (PW) and minimal cross-sectional area (CSmin) were also considered.

RESULTS

All PAs' volumetric sub-regions, CSmin and PW showed a significant volumetric increment (p < 0.05). Inter-group comparisons showed significant differences (p < 0.05) for nasopharynx and CSmin parameters (p < 0.05), while no significant changes were recorded for the other UA's sub-regions and PW (p > 0.05). According to a deviation analysis, part of the UA increase (more marked for the nasopharynx area) may have occurred due to reduced adenotonsillar tissues, which were larger in the EEG group.

CONCLUSIONS

Twelve months after treatment, clinicians should not expect changes in the UAs dimensions to be solely related to treatment effects of RME; instead, normal craniofacial growth changes and spontaneous regression of the adenotonsillar tissue could represent the most significant factors influencing UAs changes.

CLINICAL SIGNIFICANCE

From the clinical perspective, the results of the present study encourage caution when considering the therapeutic effects of RME on airways dimensions.