Hyoid Bone Positional Changes, Maxillary Constriction in Growing Children, Orthodontic Expansion Effects, Transverse Maxillary Deficiency, Upper Airway Morphology in Children
Conditions
Keywords
BREA, MFT expander, palatal expansion, maxillary expansion, upper airway
Brief summary
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.
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.
Interventions
DEVICEMaxillary 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.
DEVICEBimaxillary 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.
Sponsors
Medical University of Silesia
Study design
Allocation
NON_RANDOMIZED
Intervention model
PARALLEL
Primary purpose
OTHER
Masking
NONE
Masking description
Due to the retrospective design and the nature of orthodontic appliances, participants, care providers, and investigators were not masked. Outcome measurements were performed using calibrated digital methods to reduce measurement bias.
Intervention model description
Participants are allocated to one of three parallel groups according to clinical management: (1) treatment with a maxillary fixed three screw palatal expander (MFT), (2) treatment with a bimaxillary removable expansion appliance (BREA), or (3) untreated control with observational follow up. The study is retrospective and based on analysis of existing clinical records and imaging obtained at two time points. No randomization was performed, and group allocation reflected routine orthodontic decision making. Outcomes were compared longitudinally between groups.
Eligibility
Sex/Gender
ALL
Age
4 Years to 12 Years
Healthy volunteers
Yes
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Change in upper airway and hyoid positional measurements on cephalometry | Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration) | 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. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Changes in palatal morphology and transverse interdental dimensions | Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration) | 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. |
| Change in piriform aperture transverse width | Baseline and post-treatment observation period (mean approximately 6 to 12 months, depending on individual treatment duration) | 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. |
Countries
Poland
Outcome results
None listed