Effects of BREA and MFT Expansion Appliances on Upper Airway Dimensions

Effects of BREA and MFT Expansion Appliances on Upper Airway Dimensions, Hyoid Bone Position and Palatal Morphology in Growing Children

This retrospective study evaluated whether orthodontic expansion using two types of appliances, a bimaxillary removable expansion appliance (BREA) and a maxillary fixed three screw palatal expander (MFT), influences upper airway dimensions, hyoid bone position, and palatal morphology in growing children. Seventy nine children aged 4 to 12 years were included. Fifty five patients received orthodontic expansion (BREA or MFT), and twenty four untreated patients served as controls. Lateral and posteroanterior cephalometric radiographs and digital dental models obtained before and after the observation period were analyzed. Measurements assessed nasal and hypopharyngeal airway dimensions, the position of the hyoid bone, and transverse and volumetric characteristics of the palate. Compared with untreated children, those who underwent expansion showed significant increases in selected airway dimensions, widening of the upper piriform aperture, and increased distance between the hyoid bone and the mandibular symphysis. Both appliances increased maxillary transverse widths, with greater maxillary expansion observed in the MFT group. Palatal volume increased significantly with BREA, whereas palatal surface area increased and palatal depth decreased significantly with MFT. These findings suggest that orthodontic expansion in growing children may favorably modify selected upper airway and palatal parameters. Further prospective studies are needed to determine the long term functional and clinical significance of these changes.

Study Overview

• Status: Completed
• Conditions: Transverse Maxillary Deficiency; Maxillary Constriction in Growing Children; Upper Airway Morphology in Children; Orthodontic Expansion Effects; Hyoid Bone Positional Changes
• Intervention / Treatment: Device: Maxillary fixed three screw palatal expander (MFT); Device: Bimaxillary removable expansion appliance (BREA)

Detailed Description

This retrospective observational study was designed to evaluate dentofacial and upper airway changes associated with orthodontic expansion in growing children. The analysis focused on two expansion modalities: a bimaxillary removable expansion appliance (BREA) and a maxillary fixed three screw palatal expander (MFT). The primary objective was to determine whether these appliances influence piriform aperture width, hypopharyngeal dimensions, hyoid bone position, and palatal morphology during active craniofacial growth. The study included children aged 4 to 12 years who underwent comprehensive orthodontic diagnostics in a private orthodontic practice. Eligible patients had no history of cleft lip or palate, no previous orthodontic treatment, and no interdental spacing or diastema. The treated cohort comprised patients managed with either BREA or MFT according to clinical indications. A control cohort consisted of patients who completed full orthodontic diagnostics at two time points but did not initiate treatment. Ethical approval was obtained from the Bioethics Committee of the Medical University of Silesia. Standardized lateral and posteroanterior cephalometric radiographs were obtained in natural head position with controlled occlusion and breathing conditions. Digital dental models were generated from alginate impressions and intraoral scanning. Two dimensional airway and hyoid measurements were derived from calibrated cephalograms using dedicated cephalometric software. Three dimensional palatal surface area, volume, depth, and transverse interdental distances were calculated from digital models using certified orthodontic software. The primary analytical approach compared longitudinal changes between treated and untreated groups. Independent samples tests and analysis of covariance were applied to two dimensional variables, adjusting for sex and baseline age. One way analysis of variance with post hoc testing was used for three dimensional comparisons between appliance subgroups. Statistical significance was predefined at p less than 0.05. The study was exploratory in nature and aimed to characterize morphologic trends associated with early orthodontic expansion rather than to establish causal clinical outcomes. No therapeutic interventions beyond routine orthodontic care were introduced for research purposes. The results are intended to inform future prospective investigations evaluating functional respiratory and craniofacial implications of expansion therapy in pediatric populations.

• Study Type: Interventional
• Enrollment (Actual): 79
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Poland
  • Zabrze, Poland
    • Silesian Medical University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Child
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

Children aged 4 to 12 years at baseline. Patients in primary or mixed dentition stage.

Availability of complete orthodontic diagnostic records at two time points, including:

lateral cephalometric radiograph posteroanterior cephalometric radiograph dental models suitable for digital analysis For treated groups: orthodontic expansion performed with either BREA or MFT according to routine clinical indications.

For control group: patients who underwent full orthodontic diagnostics but did not initiate orthodontic treatment during the observation period.

Good general health without systemic conditions known to significantly affect craniofacial growth.

Exclusion Criteria:

Presence of cleft lip and/or palate. Previous orthodontic treatment prior to baseline records. Presence of generalized spacing or diastema that could affect transverse measurements.

Incomplete or missing radiographic records. Poor quality radiographs preventing reliable cephalometric analysis. Poor quality dental models, including artifacts on the palatal surface or indistinct gingival margins.

Craniofacial syndromes or conditions known to significantly alter craniofacial development.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Non-Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: MFT Expansion Group; Participants received orthodontic treatment with a maxillary fixed three screw palatal expander (MFT) as part of routine clinical care. The appliance consisted of acrylic splints on the maxillary posterior teeth connected by a central Hyrax type screw and two auxiliary screws. The central screw was activated once daily and the lateral screws every five days according to the clinical protocol. Cephalometric radiographs and digital dental models obtained before and after treatment were analyzed to assess airway, hyoid, and palatal changes.	Device: Maxillary fixed three screw palatal expander (MFT); A fixed orthodontic maxillary expansion device anchored to posterior teeth with acrylic splints and incorporating one central Hyrax type expansion screw and two auxiliary transverse screws. The central screw was activated once daily (up to 28 turns) and the lateral screws once every five days (up to 10 turns) according to the clinical protocol. The appliance was used in growing children to achieve transverse maxillary expansion. Treatment and imaging were part of routine orthodontic care.; Other Names: Three screw maxillary expander; MFT appliance; Hyrax type maxillary expander (modified)
Experimental: BREA Expansion Group; Participants were treated with a removable bimaxillary expansion appliance (BREA) worn full time except during meals and oral hygiene. The device incorporated two expansion screws, one in the maxillary arch and one in the mandibular arch, both activated once weekly in the horizontal plane. Treatment followed routine orthodontic indications. Pre and post observation cephalometric radiographs and digital models were analyzed to evaluate changes in airway dimensions, hyoid position, and palatal morphology.	Device: Bimaxillary removable expansion appliance (BREA); A removable orthodontic appliance designed for simultaneous maxillary and mandibular transverse expansion. The device contains two expansion screws, one positioned in the maxillary arch and one in the mandibular arch. It was worn full time except during meals and oral hygiene. Both screws were activated once weekly in the horizontal plane according to the treatment protocol. The appliance was used in growing children as part of standard orthodontic management.; Other Names: BREA appliance; Removable bimaxillary expander; Two screw removable expander
No Intervention: Untreated Control Group; Participants underwent standard orthodontic diagnostics at two time points but did not receive expansion therapy. These patients declined treatment and were followed observationally. Paired cephalometric radiographs and digital dental models were analyzed over the observation interval to provide a reference for natural growth related changes in airway parameters, hyoid position, and palatal morphology.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change in upper airway and hyoid positional measurements on cephalometry	The primary outcome is the longitudinal change in selected upper airway and hyoid bone parameters measured on calibrated lateral and posteroanterior cephalometric radiographs. Key variables include piriform aperture width (NCULPA-NCURPA), hypopharyngeal airway dimension at C4ia (Z5-Z6), and the linear distance between the hyoid bone and mandibular symphysis (rGn-H). Values are calculated as the difference between post-treatment and baseline measurements and compared between study arms.	Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Changes in palatal morphology and transverse interdental dimensions	Secondary outcomes include three dimensional changes in palatal morphology and dental arch width derived from digital models. Assessed variables comprise palatal volume (PV), palatal surface area (PSA), palatal depth (PD1, PD2), palatal length (PL), and transverse interdental distances in the maxillary and mandibular arches (3+3, 4+4, 5+5, 6+6 and 3-3, 4-4, 5-5, 6-6). Measurements are calculated as post minus pre values normalized to the observation period and compared between study arms.	Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration)
Change in piriform aperture transverse width	This secondary outcome evaluates the longitudinal change in the transverse dimension of the piriform aperture measured on calibrated posteroanterior cephalometric radiographs. The primary variable is NCULPA-NCURPA. Values are calculated as the difference between post-observation and baseline measurements and compared across study arms to assess the effect of orthodontic expansion on the bony nasal inlet.	Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration)

Collaborators and Investigators

• Sponsor: Medical University of Silesia

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2020
• Primary Completion (Actual): February 1, 2026
• Study Completion (Actual): February 1, 2026

Study Registration Dates

• First Submitted: March 2, 2026
• First Submitted That Met QC Criteria: March 2, 2026
• First Posted (Actual): March 9, 2026

Study Record Updates

• Last Update Posted (Actual): March 9, 2026
• Last Update Submitted That Met QC Criteria: March 2, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Keywords: upper airway; palatal expansion; maxillary expansion; BREA; MFT expander
• Other Study ID Numbers: PCN/0022/KB1/11/21

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No