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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
A randomized control trial investigating the effectiveness of three different upper jaw expansion devices in correcting narrow upper jaws in 10-16 year old children.
Scientific title
Randomized clinical trial investigating the airway, facial, dental and skeletal changes from bone and tooth anchored rapid palatal expansion (Hybrid Hyrax) versus tooth borne rapid palatal expansion (Hyrax) versus a novel keyless tooth borne palatal expansion device in 10-16 year old children.
Secondary ID [1] 292529 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Constricted Maxilla 304194 0
Condition category
Condition code
Oral and Gastrointestinal 303529 303529 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Study type
Description of intervention(s) / exposure
All patients recruited to this research will be given one of three different information brochures, (Parents; 10-12 year olds, and 12-16 year olds) with each adjusted to the relavent reading age. Each brochure has information regarding the three different possible interventions; possible side effects; participation requirements and contact information of the researchers. Prior to the intervention, patients will have photos, 3d photographic scans, study casts of their teeth, and cone beam CT taken to record as baseline values.
There are three seperate intervention arms: Arm 1: Hyrax expansion group (which will act as control) Arm 2: Hybrid Hyrax expansion group, Arm3: Keles expansion group.
These will all be performed at the Sydney Dental Hospital by three different training Orthodontic registrars under the supervision of one professor and two senior lectures who have a minimum of 15 years experience in Orthodontics.

Once recruited, each patient is randomized into one of three arms. The key difference in the interventions is described below
Arm 1 Hyrax: to use a conventional expansion device which is attached only to the first upper premolars and upper first molars
Arm 2 Hybrid Hyrax: to use a conventional expansion device which is attached to the first upper molars but also to two mini implants that are placed in the palate
Arm 3 Keles Expansion: A novel expansion device which is similar to the conventional expansion device in action and attached to the upper first premolars and molars, with the only difference being that the device has a built in operating arm, whereas the conventional expansion device requires an external key.

In all three groups, the participants will be instructed to turn the expansion device twice a day, resulting in 0.5mm of expansion a day. The use of the device will be demonstrated to the patient and their guardians, as well as an instructional video given for home viewing. Interventional adherence will be monitored by using a calendar and patients reviewed on a weekly basis. They will be continued to be monitored weekly at Sydney Dental hospital until it is determined that an adequate amount of expansion has been achieved and then instructed to stop turning. This will be determined by the orthodontic registar and defined as when there is no longer a posterior crossbite between the upper and lower dentition. The expansion device will then be locked so that no further turning can occur. Patients will then have 6 months of the devices in situ to stabilize the expansion. After 6 months the devices will be removed and new records taken.
Fixed orthodontic appliances will then be placed to correct any further orthodontic issues.
Intervention code [1] 298735 0
Treatment: Devices
Comparator / control treatment
The control group will be Arm1 of the research, and consists the use of a conventional Hyrax expansion device, which has been used in Orthodontics since 1968. The procedure of turning and mechanism of turning will be identitical to the other arms.
Control group

Primary outcome [1] 302898 0
Change in the angulation of the palatal root of the first molar to the palatal plane (Tor) as assesed in the sagittal view on Cone Beam CT slices.
Timepoint [1] 302898 0
Will be assesed on Cone Beam CT images taken before treatment (T0), and taken immediately after appliance removal (T1) - which will be 6 months after active expansion.
Secondary outcome [1] 337370 0
Easability of each device
Timepoint [1] 337370 0
Two surverys specific to the study will be given to patients immediately after appliance insertion and immediately after appliance removal. These will be labelled "Questionnaire 1" and "Questionnaire 2". The only difference between the two being the addition of an extra question asking the patient to clarify how many turns they have completed of the appliance during the active treatment period. There will be a Visual Analog scale from 0-10, with 10 being a postive response, and 0 being a negative response.
Secondary outcome [2] 337371 0
Changes in nasal floor width as assessed on sagittal slices of Cone Beam CT
Timepoint [2] 337371 0
Will be assesed on Cone Beam CT images taken before treatment (T0), and taken immediately after appliance removal (T1) - which will be 6 months after active expansion.
Secondary outcome [3] 337372 0
Changes in Hard palate width as measured on Cone Beam CT slices
Timepoint [3] 337372 0
Will be assesed on Cone Beam CT images taken before treatment (T0), and taken immediately after appliance removal (T1) - which will be 6 months after active expansion.
Secondary outcome [4] 337373 0
Changes in upper airway volume as measured on Cone Beam CT using a segmentation technique.
Timepoint [4] 337373 0
Will be assesed on Cone Beam CT images taken before treatment (T0), and taken immediately after appliance removal (T1) - which will be 6 months after active expansion.

Key inclusion criteria
Transverse discrepancy between the maxilla and mandible to be more than 5mm as measured from the upper first molar palatal cusp tips to the lower first molar groove

Erupted permanent maxillary first molars and first premolars

Minimum age
10 Years
Maximum age
16 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
o Unerupted permanent maxillary first premolars or first molars
o History of previous orthodontic treatment
o Women who are pregnant
o People with an intellectual or mental impairment
o People highly dependent on medical care
o History of congenital deformity
o Periodontal disease
o Surgical treatment that may affect the rapid maxillary expansion outcome

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Central randomization by computer randomisation.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
o We will allocate each patient a number from 1-75, and then utilising the following (randomizer.org) we will randomly generate the three treatment arms with these allocated numbers.

Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
The assessment of Tor (the change in angulation of palatal root to palatal plane)
SD: 1.5
A significant difference of 2°
To use the t-test twice to compare the two groups relative to control (Hyrax) - Hyrax vs Keles and Hyrax vs Hybrid-Hyrax
a = 0.025, 1-a = 0.975
Power = 90%
Patients required = 15 per group
To accommodate for drop outs, N= 60

Recruitment status
Not yet recruiting
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment hospital [1] 8623 0
Sydney Dental Hospital - Surry Hills
Recruitment postcode(s) [1] 16731 0
2010 - Surry Hills

Funding & Sponsors
Funding source category [1] 297099 0
Name [1] 297099 0
University of Sydney
Address [1] 297099 0
Orthodontic Department of University of Sydney
Level 2, Sydney Dental Hospital,
2 Chalmers Street
Surry Hills
Sydney 2010
New South Wales

Country [1] 297099 0
Primary sponsor type
Sydney Dental Hospital
Sydney Dental Hospital,
2 Chalmers Street
Surry Hills
Sydney 2010
New South Wales
Secondary sponsor category [1] 296108 0
Name [1] 296108 0
Address [1] 296108 0
Country [1] 296108 0

Ethics approval
Ethics application status
Ethics committee name [1] 298276 0
Sydney Local Health District Human Research Eethics Committee
Ethics committee address [1] 298276 0
Research Ethics and Governance Office (REGO)
Royal Prince Alfred Hospital
Missenden Road
Ethics committee country [1] 298276 0
Date submitted for ethics approval [1] 298276 0
Approval date [1] 298276 0
Ethics approval number [1] 298276 0

Brief summary
This study is to find if one type of expander (a plate) is better at widening the upper jaw of children aged 10-16. The expander will be placed on their top teeth and will be one of the following:

1) Hyrax Expander: this is the common type of expander which requires a separate key to turn.
2) Hybrid-Hyrax Expander: this is the normal expander but it also includes two pins placed in the top of the upper jaw (palate)
3) Keles Expander: this is a new type of expander which has a built-in key to turn the expander. This new type of expander is not yet approved by Therapeutic Goods Administration.

Our hypothesis is that the Keles expander will work as equally as effectively as the Hyrax, whereas the Hybrid-Hyrax will be more effective in expanding the jaw due to the use of the two palatal pins.
Patients will be recruited at the Sydney Dental Hospital and will be included if they meet the inclusion criteria of having a narrow jaw and in the correct age range. Exclusion criteria include if patients have had previous orthodontic treatment and/or any serious health issues that may impact orthodontic treatment.
60 selected patients will be randomly placed into 3 groups of 20 patients each. Records of patients will be taken before treatment. The appliance will be constructed and installed on each patient. Patients will be taught to turn the expander and will continue expanding until the correct amount of expansion has been achieved. After this, the expander will be locked to prevent further turning and the patient left with the expander in-situ for 6 months to retain the changes in the expanded jaw. The expander is then removed and then new records taking. Patients are then followed up to continue with normal braces treatment as per normal.

The records taken of participants will include: questionaires, photos, study casts, 3d photos, and Cone Beam CT images.
The data retrieved from these records will be used to assess the dental, skeletal, facial and airyway changes as a result of the expansion. The primary outcome will be to assess the change in angulation of upper first molars relatve to the palate in cross section on Cone Beam CT images. Secondary outcomes include: easability of the difference appliances, airway changes, facial changes and skeletal changes measured on CT images..
Trial website
Trial related presentations / publications
Public notes
Attachments [1] 1918 1918 0 0
Attachments [2] 1919 1919 0 0
/AnzctrAttachments/373376-0757_001.pdf (Ethics approval)
Attachments [3] 1920 1920 0 0
/AnzctrAttachments/373376-Information sheet for adolescents v1.2 Final.docx (Participant information/consent)
Attachments [5] 1922 1922 0 0
/AnzctrAttachments/373376-Information sheet for parents 1.3 Final.docx (Participant information/consent)
Attachments [6] 1923 1923 0 0
/AnzctrAttachments/373376-RME Parent Guardian Consent Form 1.2 Final.doc (Participant information/consent)
Attachments [7] 1924 1924 0 0
/AnzctrAttachments/373376-RME Participant Consent Form 1.3 Final.doc (Participant information/consent)

Principal investigator
Name 76562 0
Prof Mehmet Ali Darendililer
Address 76562 0
Orthodontic Department
Level 2, Sydney Dental Hospital
2 Chalmers Street
Surry Hills 2010
New South Wales
Country 76562 0
Phone 76562 0
+612 93518314
Fax 76562 0
Email 76562 0
Contact person for public queries
Name 76563 0
Dr Gordon Cheung
Address 76563 0
Orthodontic Department
Level 2, Sydney Dental Hospital
2 Chalmers Street
Surry Hills 2010
New South Wales
Country 76563 0
Phone 76563 0
+612 93518314
Fax 76563 0
Email 76563 0
Contact person for scientific queries
Name 76564 0
Dr Gordon Cheung
Address 76564 0
Orthodontic Department
Level 2, Sydney Dental Hospital
2 Chalmers Street
Surry Hills 2010
New South Wales
Country 76564 0
Phone 76564 0
+612 93518314
Fax 76564 0
Email 76564 0

No information has been provided regarding IPD availability
Summary results
No Results