ApneaNCT04190953
Upper Airway's Pressure Drop Analyses After Mandibular Advancement and Maxillary Expansion
A study testing Twin block then Hyrax and Hyrax then Twin block in people with Apnea and Airway Obstruction, Nasal, run by University of Alberta at 1 site in Canada.
Trial summary
Breathing is a crucial function for everyone. Breathing impairment in children could lead to behavioral and cognitive problems at least. But what if orthodontic treatment could help those patients to breathe better, with less effort? This research proposal aims to find out if the increase in the upper airway volume… Read more about this study
- Who is it for?
- Ages 8 to 14 yearsHealthy volunteers can take part
- Conditions the study is for
- Apnea, Airway Obstruction, Nasal, Mandible Small
- What is being tested?
- Twin block then Hyrax and Hyrax then Twin block
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 90 participants
- Where
- 1 siteCanada
- Study dates
- 18 Feb 2020to 1 Mar 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 8 to 14 years
- All sexes
- Healthy volunteers accepted
- Child
Who may be able to join
- children between the ages 8-14 years old (8-12 years old girls and 9-14 years old boys), presenting skeletal class II division 1 malocclusion with maxillary constriction
Who cannot join
- syndromic patients, previous ortho history, non-compliance, severe oral health issues (cavities, poor oral hygiene)
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Canada1 site, 1 recruiting
- Recruiting
University of Alberta
Edmonton, Alberta, T6G 2R3
SILVIA GIANONI-CAPENAKAS, 5875949947, capenaka@ualberta.ca
About this study
Official title: Skeletal, Dental and Upper Airway Changes in Skeletal Class II Division 1 Patients With the Constricted Maxilla (8-14 Years Old) Treated With Twin Block and Hyrax, Evaluated Through Pressure Drop Experimental Analysis.
Breathing is a crucial function for everyone. Breathing impairment in children could lead to behavioral and cognitive problems at least. But what if orthodontic treatment could help those patients to breathe better, with less effort? This research proposal aims to find out if the increase in the upper airway volume seen in some research results can be related to a decrease in respiratory effort and an improvement in the breathing capacity of those patients. In other words, if a tube shape is changed or if a tube is enlarged, would the airflow passing inside the tube change in velocity? Or would there be more air? Therefore, investigating the pressure/airflow, volume/lumen relation and its possible changes after mandibular repositioning and maxillary expansion in children will lead to a better understanding of how orthodontics could potentially affect the upper airway. Previous studies have reported a link between mandibular advancement appliances and maxillary appliances to an increase in the upper airway volume. However, more studies are needed to evaluate the relationship between the changes in the upper airway volume and actual airflow and respiratory capability. The airway volume measurement is important to, preliminary, state if there is an increase in the upper airway after orthodontic treatment.
However a change in shape, even with the same volume, can affect the pressure and airflow. In this sense, the pressure drop analysis will allow an answer to those questions
Read the detailed description
Our hypotheses are:
- There is an increase in upper airway volume and minimal cross-sectional area after maxillary expansion and mandible repositioning in class II malocclusion children using Hyrax and Twin-block.
- There is a larger increase in the airway dimensions and a larger decrease in the air resistance (in the pressure drop analysis) in the group started with the mandibular advancement device.
- There is a change in the shape of the upper airway after maxillary expansion and mandible repositioning in class II malocclusion children using Hyrax and Twin-block.
- There is a correlation between the increase in airway volume, the change in shape and an increase in airflow using in vitro simulated airway experiments.
- There is an increase in respiratory capability when evaluated with in-home portable PSG (after maxillary expansion and mandible repositioning).
- There is a positive correlation to the in-home portable Polysomnography (PSG) with the results acquired by volume, shape, airflow and pressure drop.
Methods
The inclusion criteria are children between the ages 8-14 years old (8-12 years old girls and 9-14 years old boys), presenting skeletal class II division 1 malocclusion with maxillary constriction. The study design is a randomized crossover controlled trial. 90 patients will be randomly allocated into three groups:
Group 1: 30 patients will immediately undergo to Hyrax/Twin-block treatment, the patients will have the maxillary expansion treatment (Part I) before the mandibular repositioning (Part II).
Group 2: 30 patients will immediately undergo Twin-block/Hyrax treatment, the patients will have the mandibular repositioning treatment (Part I) done before the maxillary expansion (Part II).
Group 3: 30 patients will wait 1,5 years to begin the treatment. Since all patients are in the pre-pubertal/pubertal phase, this 1,5-year delay treatment for group 3 will neither compromise future treatment decisions nor results.
Aim 1: To determine the changes in the upper airway volume, minimal cross-sectional area, the lumen (geometry/shape), airflow, air velocity and pressure after maxillary expansion and mandibular advancement in children. Those changes will be compared between tested and control groups.
The upper airway will be assessed through Cone Bean Computed Tomography (CBCT)s exams, to analyze the volume changes before and after the use of the Twin-block and Hyrax, using the Avizo software (Thermo Fisher Scientific, Berlin, Germany). The pressure drop will be assessed using the CBCTs to generate a Stereolithography (STL) file to print upper airway models to analyze airflow, air velocity and pressure characteristics before and after the orthodontic treatment in children. Those results will be correlated. Also, the correlation will be done between tested and control groups. Pressure drop related measurements and airway volume will be assessed at T0 - before treatment, T1- after part II in the treated groups and T0 and after 1.5 years in the control group.
Aim 2: To determine changes in the in-home portable PSG results before and after maxillary expansion and mandibular repositioning and to correlate them to the results collected by the upper airway model's evaluations using pressure drop to determine airflow, velocity, pressure, and upper airway dimensions.
Patients will undergo an in-home PSG test at the beginning of treatment (T0). Groups 1 and 2 will have in-home PSG tested again after Part I and II. Group 3 will be tested at T0 and after one year. Through the CBCTs the volume and minimal cross-sectional area, and related measurements to pressure drop test will be assessed and correlated to the results from the in-home portable PSG. Likewise, the changes will be compared between tested and control groups.
Aim 3: To describe dental and skeletal changes in the class II patients undertaken the Twin-block/Hyrax treatment.
Linear measurements using craniofacial landmarks will be assessed through CBCT exams to determine the amount of skeletal and dental changes obtained. All patients will have those measurements assessed at T0. Groups 1 and 2 will also have linear measurements assessed after Part II. Group 3 will have linear measurements reassessed after 1.5 years from the first CBCT.
General information The CBCTs will be analyzed using Avizo software (Thermo Fisher Scientific, Berlin, Germany) for volume and linear measurement. Printed upper airway for the Pressure drop test for airflow/pressure drop/air velocity simulations will be made at all time-points.
All patients will have breathing capacity tested through in-home portable PSG, one week before the beginning of treatment, after parts I and II in groups 1 and 2 and at T0 and 1.5 years after the first test for group 3.
A subjective evaluation of the airway using the questionnaire Nasal Obstruction Symptom Evaluation (NOSE) Instrument, with 18 questions, will be given to patients. A Paediatric Sleep Questionnaire (PSQ) will also be used. An objective airway evaluation will be made using Peak Nasal Inspiratory Flow (PNIF) and Peak Oral Inspiratory Flow (POIF) tests, which are measured with the In-Check medical device at the same time-points as in-home PSG tests. Those tests and questionnaires will be used to correlate all the findings and clinical significance.
- Conditions
- Apnea, Airway Obstruction, Nasal, Mandible Small, Maxillary Hypoplasia
- Being tested
- Twin block then Hyrax, Hyrax then Twin block
- Medical subject headings
- Apnea, Nasal Obstruction, Micrognathism, Retrognathia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Twin block then HyraxOther
Patients will undergo mandibular advancement prior to maxillary expansion
Hyrax then Twin blockOther
Patients will undergo maxillary expansion prior to mandibular advancement
| Study group | Role | What they receive |
|---|---|---|
| Twin Block then Hyrax | Experimental | Patients will undergo mandibular advancement prior to maxillary expansion using Twin block prior to Hyrax Receives: Other: Twin block then Hyrax |
| Hyrax then Twin block | Experimental | Patients will undergo maxillary expansion prior to mandibular advancement using Hyrax prior to Twin block Receives: Other: Hyrax then Twin block |
| Control | No intervention | Patients will wait 1,5 years before the start of treatment |
What is being measured
The primary outcome is the main question the study is designed to answer.
Airflow
Airflow of the upper airway using pressure drop experimental analyzed using the CBCTs scans to print out the models of the upper airway.
Measured: 3 years
Secondary outcomes (2)
Dental changes
Dental changes after orthodontic treatment. Measurements of the teeth in relation to several cranial based landmarks will be made to analyse teeth movements. Those measurements will be done using the CBCTs scans.
Measured: 3 years
Skeletal changes
Skeletal changes after orthodontic treatment. Measurements of 29 landmarks inside the skull will be made to verify the changes related to bone. The CBCTs scans will be used.
Measured: 3 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted9 Dec 2019
- Study start18 Feb 2020
- Primary completion1 Mar 2027 (estimated)
- Study completion1 Mar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ApneaStudies of the same condition, open and under way.
- More trials run by University of AlbertaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- Twin block and Hyrax appliances will be installed in 1/3 of the patients, while hyrax and twin block devices will be applied to the other 1/3 of the patients. Another 1/3 of patients will be the control group with no treatment
- Masking
- Single blind
- Who is masked
- Outcomes assessor
- Enrolment
- 90 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Alberta
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Silvia G Capenakas, MSc, Principal investigator, University of Alberta
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT04190953
- Sponsor's protocol ID
- Pro00095427
- Status last verified
- Mar 2026
- First submitted
- 21 Nov 2019
- Last updated
- 18 Mar 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No: Data won't be shared for confidential reasons and all data will be grouped.
Study at a glance
From the registry record, last updated by the sponsor on 18 Mar 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Skeletal, Dental and Upper Airway Changes in Skeletal Class II Division 1 Patients With the Constricted Maxilla (8-14 Years Old) Treated With Twin Block and Hyrax, Evaluated Through Pressure Drop Experimental Analysis.
- ClinicalTrials.gov ID
- NCT04190953
- Acronym / sponsor ID
- Pro00095427
- Conditions
- Apnea, Airway Obstruction, Nasal, Mandible Small, Maxillary Hypoplasia
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 90 participants (estimated)
- Lead sponsor
- University of AlbertaUniversity, hospital or other
- Study start
- 18 Feb 2020 (actual)
- Primary completion
- 1 Mar 2027 (estimated)
- Study completion
- 1 Mar 2027 (estimated)
- First posted
- 9 Dec 2019 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Breathing is a crucial function for everyone. Breathing impairment in children could lead to behavioral and cognitive problems at least. But what if orthodontic treatment could help those patients to breathe better, with less effort? This research proposal aims to find out if the increase in the upper airway volume seen in some research results can be related to a decrease in respiratory effort and an improvement in the breathing capacity of those patients. In other words, if a tube shape is changed or if a tube is enlarged, would the airflow passing inside the tube change in velocity? Or would there be more air? Therefore, investigating the pressure/airflow, volume/lumen relation and its possible changes after mandibular repositioning and maxillary expansion in children will lead to a better understanding of how orthodontics could potentially affect the upper airway. Previous studies have reported a link between mandibular advancement appliances and maxillary appliances to an increase in the upper airway volume. However, more studies are needed to evaluate the relationship between the changes in the upper airway volume and actual airflow and respiratory capability. The airway volume measurement is important to, preliminary, state if there is an increase in the upper airway after orthodontic treatment.
However a change in shape, even with the same volume, can affect the pressure and airflow. In this sense, the pressure drop analysis will allow an answer to those questions
Detailed description
Our hypotheses are:
- There is an increase in upper airway volume and minimal cross-sectional area after maxillary expansion and mandible repositioning in class II malocclusion children using Hyrax and Twin-block.
- There is a larger increase in the airway dimensions and a larger decrease in the air resistance (in the pressure drop analysis) in the group started with the mandibular advancement device.
- There is a change in the shape of the upper airway after maxillary expansion and mandible repositioning in class II malocclusion children using Hyrax and Twin-block.
- There is a correlation between the increase in airway volume, the change in shape and an increase in airflow using in vitro simulated airway experiments.
- There is an increase in respiratory capability when evaluated with in-home portable PSG (after maxillary expansion and mandible repositioning).
- There is a positive correlation to the in-home portable Polysomnography (PSG) with the results acquired by volume, shape, airflow and pressure drop.
Methods
The inclusion criteria are children between the ages 8-14 years old (8-12 years old girls and 9-14 years old boys), presenting skeletal class II division 1 malocclusion with maxillary constriction. The study design is a randomized crossover controlled trial. 90 patients will be randomly allocated into three groups:
Group 1: 30 patients will immediately undergo to Hyrax/Twin-block treatment, the patients will have the maxillary expansion treatment (Part I) before the mandibular repositioning (Part II).
Group 2: 30 patients will immediately undergo Twin-block/Hyrax treatment, the patients will have the mandibular repositioning treatment (Part I) done before the maxillary expansion (Part II).
Group 3: 30 patients will wait 1,5 years to begin the treatment. Since all patients are in the pre-pubertal/pubertal phase, this 1,5-year delay treatment for group 3 will neither compromise future treatment decisions nor results.
Aim 1: To determine the changes in the upper airway volume, minimal cross-sectional area, the lumen (geometry/shape), airflow, air velocity and pressure after maxillary expansion and mandibular advancement in children. Those changes will be compared between tested and control groups.
The upper airway will be assessed through Cone Bean Computed Tomography (CBCT)s exams, to analyze the volume changes before and after the use of the Twin-block and Hyrax, using the Avizo software (Thermo Fisher Scientific, Berlin, Germany). The pressure drop will be assessed using the CBCTs to generate a Stereolithography (STL) file to print upper airway models to analyze airflow, air velocity and pressure characteristics before and after the orthodontic treatment in children. Those results will be correlated. Also, the correlation will be done between tested and control groups. Pressure drop related measurements and airway volume will be assessed at T0 - before treatment, T1- after part II in the treated groups and T0 and after 1.5 years in the control group.
Aim 2: To determine changes in the in-home portable PSG results before and after maxillary expansion and mandibular repositioning and to correlate them to the results collected by the upper airway model's evaluations using pressure drop to determine airflow, velocity, pressure, and upper airway dimensions.
Patients will undergo an in-home PSG test at the beginning of treatment (T0). Groups 1 and 2 will have in-home PSG tested again after Part I and II. Group 3 will be tested at T0 and after one year. Through the CBCTs the volume and minimal cross-sectional area, and related measurements to pressure drop test will be assessed and correlated to the results from the in-home portable PSG. Likewise, the changes will be compared between tested and control groups.
Aim 3: To describe dental and skeletal changes in the class II patients undertaken the Twin-block/Hyrax treatment.
Linear measurements using craniofacial landmarks will be assessed through CBCT exams to determine the amount of skeletal and dental changes obtained. All patients will have those measurements assessed at T0. Groups 1 and 2 will also have linear measurements assessed after Part II. Group 3 will have linear measurements reassessed after 1.5 years from the first CBCT.
General information The CBCTs will be analyzed using Avizo software (Thermo Fisher Scientific, Berlin, Germany) for volume and linear measurement. Printed upper airway for the Pressure drop test for airflow/pressure drop/air velocity simulations will be made at all time-points.
All patients will have breathing capacity tested through in-home portable PSG, one week before the beginning of treatment, after parts I and II in groups 1 and 2 and at T0 and 1.5 years after the first test for group 3.
A subjective evaluation of the airway using the questionnaire Nasal Obstruction Symptom Evaluation (NOSE) Instrument, with 18 questions, will be given to patients. A Paediatric Sleep Questionnaire (PSQ) will also be used. An objective airway evaluation will be made using Peak Nasal Inspiratory Flow (PNIF) and Peak Oral Inspiratory Flow (POIF) tests, which are measured with the In-Check medical device at the same time-points as in-home PSG tests. Those tests and questionnaires will be used to correlate all the findings and clinical significance.
Study design
- Primary purpose
- Other
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (outcomes assessor)
- Number of arms
- 3
- Model description
- Twin block and Hyrax appliances will be installed in 1/3 of the patients, while hyrax and twin block devices will be applied to the other 1/3 of the patients. Another 1/3 of patients will be the control group with no treatment
| Arm | Type | Receives |
|---|---|---|
| Twin Block then Hyrax | Experimental | Other: Twin block then HyraxPatients will undergo mandibular advancement prior to maxillary expansion using Twin block prior to Hyrax |
| Hyrax then Twin block | Experimental | Other: Hyrax then Twin blockPatients will undergo maxillary expansion prior to mandibular advancement using Hyrax prior to Twin block |
| Control | No intervention | –Patients will wait 1,5 years before the start of treatment |
Who may qualify
- Ages
- 8 to 14 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Child
Key inclusion criteria (1 listed)
- children between the ages 8-14 years old (8-12 years old girls and 9-14 years old boys), presenting skeletal class II division 1 malocclusion with maxillary constriction
Key exclusion criteria (1 listed)
- syndromic patients, previous ortho history, non-compliance, severe oral health issues (cavities, poor oral hygiene)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Twin block then HyraxPatients will undergo mandibular advancement prior to maxillary expansion | Other | Twin Block then Hyrax |
| Hyrax then Twin blockPatients will undergo maxillary expansion prior to mandibular advancement | Other | Hyrax then Twin block |
Primary outcome
Airflow
Time frame: 3 years
Airflow of the upper airway using pressure drop experimental analyzed using the CBCTs scans to print out the models of the upper airway.
2 secondary outcomes
Dental changes
Time frame: 3 years
Skeletal changes
Time frame: 3 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Mar 2026.
- Individual participant dataSharing planned: No. Data won't be shared for confidential reasons and all data will be grouped.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Silvia G Capenakas, MSc principal investigator
University of Alberta
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Twin block then Hyrax and Hyrax then Twin block in people with Apnea and Airway Obstruction, Nasal, run by University of Alberta at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 18 Mar 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Manuel Lagravere, PHD (7804927696, manuel@ualberta.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Airflow (time frame: 3 years). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Mar 2026.