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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
Assessment of tooth movement with different types of orthodontic removable retainers in patients who have had orthodontic treatment
Scientific title
Comparison of stability and occlusal contacts with different types of removable retainers in patients who have had orthodontic treatment -A prospective clinical trial
Secondary ID [1] 290044 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Retention of tooth position following orthodontic treatment
300097 0
Patient reported satisfaction with different orthodontic removable retainers 300098 0
Condition category
Condition code
Oral and Gastrointestinal 299983 299983 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Study type
Description of intervention(s) / exposure
All patients will be randomly allocated one of two commonly used removable orthodontic retainers which will be custom fit to the patients upper and lower dentition, to be worn full time for 3 months and then night time only for the remaining 3 months. The retainers will be prescribed and inserted at the orthodontists’ clinic by fully qualified orthodontists who have over 10 years of clinical experience,.

For the patients who have completed clear aligers (Invisalign) they will be randomised into two types of clear removable retainers, Vivera and Essix Ace.

The orthodontists involved in the study will meet with the investigator to be briefed of the research protocol prior to recruiting participants. An investigators’ brochure will also be distributed to ensure consistency and adherence to the method proposed.

A case report sheet will be provided to the orthodontists, which will be completed for each participant. This form will be retained at the clinic for the 6 month duration and each section will be recorded each time the participant returns to the clinic. The form includes a clinicians’ checklist for each visit such as the inclusion/exclusion criteria which was met, along with the date and details of each intra-oral scan and whether the protocol was adhered to. The clinician will sign this form at every participants' appointment and any deviation from the protocol will be documented on this form at each visit. At the conclusion of 6 months, these case report forms will be provided to the investigator to assess adherence.
Intervention code [1] 295771 0
Treatment: Devices
Comparator / control treatment
Orthodontic thermoplastic removable retainer (Essix Ace).
This is a commonly used removable retainer and will be used for patients who have had clear aligner (Invisalign) treatment.
Control group

Primary outcome [1] 299466 0
The outcome of tooth movement will be assessed by:
(1) three intra-oral digital scans taken in the clinic (no radiation exposure, are 3D digital images only)
(2) photographs taken by the participant on their phone every 2-4 weeks during the first 6 months of retention (these photos will be taken using a software called Dental Monitoring which will store the photos and record the tooth positions over time)
Timepoint [1] 299466 0
(T0) Completion of orthodontic treatment, records of patient taken including intra-oral scan for retainer fabrication
(T1) Insert removable retainer
(T2) Intra-oral scan at 3 months
(T3) Intra-oral scan at 6 months
Participant undertakes regular photos of their (i) teeth alone and (ii) teeth with the retainers in place during the 6 months of wearing their retainer
Secondary outcome [1] 327262 0
Patient reported satisfaction
The outcome of patient satisfaction will be assessed by a questionnaire specifically designed and intended for this research alone which will be completed at 3 and 6 months following insert of the orthodontic retainer. The questionnaire will ask a series of questions regarding the fit of the retainers, perceived aesthetics and ability to continue with functional tasks (e.g. speaking). The questionnaire will also enquire about compliance of wearing the retainers
Timepoint [1] 327262 0
Questionnaire will be provided at:
T2 - At 3 months of wearing the retainer
T3 - At 6 months of wearing the retainer

Key inclusion criteria
(1) Participant is over 15 years of age
(2) Participant and/or parent signed consent form
(3) Full permanent dentition present, excluding second and third molar teeth
(4) Completed Invisalign for minimum of 9 months
(5) Been prescribed upper and lower removable retainers only (no fixed retainer)
(6) Participant has access to a smartphone: Iphone 4S or later, running iOS 7.0 or later OR Android 4.0.3 or later
Minimum age
15 Years
Maximum age
No limit
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
(1) Participant receiving a fixed retainer

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Patients who are soon to complete orthodontic treatment will be offered to participate in the study. Participants will be given an information brochure and consent form. Those who sign the consent form will be immediately allocated into a retainer group.

The investigator will provide each clinician with a container of sealed opaque envelopes, inside the envelopes will contain the retainer type to be allocated (not visible through the envelope). The order of the envelopes will be randomised by computer software.

The clinician will select the next envelope, read the retainer type written within and then fabricate this retainer type for the participant. A participant ID number will also be allocated to each participant to keep the investigator blinded when assessing the results.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a computer software to generate a sequence.
The sealed opaque envelopes will be arranged in the order generated by the computer software and then provided to the clinicians.
Masking / blinding
Blinded (masking used)
Who is / are masked / blinded?
The people receiving the treatment/s

The people assessing the outcomes
The people analysing the results/data
Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Sample study calculation for each group has been undertaken with software G*Power (version 3.1), using ANOVA f-tests. With a significance level of 0.05 and 95% power with a clinically meaningful difference of 1.0mm (SD =1.0mm) a total sample of 21 participants is required. To allow for loss to follow-up participants, a total sample size of 30 participants will be obtained.

Data analysis of the tooth movements will be assessed per retainer group. ANOVA will be used to statistically analyse the tooth movements. Pearson correlation test will be used to statistically assess the relationship between the retainer and tooth movement.
The questionnaire will be analysed using a Chi-square test and a Spearman correlation test.

Recruitment status
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)

Funding & Sponsors
Funding source category [1] 294431 0
Name [1] 294431 0
University of Melbourne
Address [1] 294431 0
720 Swanston Street
Vic 3053
Country [1] 294431 0
Primary sponsor type
Australian Foundation for Orthodontic Research and Education
ASO Secretariat
P.O. Box 543
Secondary sponsor category [1] 293359 0
Name [1] 293359 0
Address [1] 293359 0
Country [1] 293359 0

Ethics approval
Ethics application status
Ethics committee name [1] 295860 0
The University of Melbourne Office for Research Ethics and Integrity
Ethics committee address [1] 295860 0
720 Swanston Street
VIC 3035

Level 3, 780 Elizabeth St
The University of Melbourne
Vic 3010)
Ethics committee country [1] 295860 0
Date submitted for ethics approval [1] 295860 0
Approval date [1] 295860 0
Ethics approval number [1] 295860 0

Brief summary
This research will compare commonly used types of orthodontic removable retainers and assess the changes in tooth position that occurs from immediately post treatment to 3 months and 6 months after orthodontic treatment is complete. Patient reported satisfaction from wearing the retainers will be assessed with the use of a questionnaire.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 68670 0
A/Prof Paul Schneider
Address 68670 0
University of Melbourne
School of Dentistry, Orthodontic Department
720 Swanston Street
VIC 3053
Country 68670 0
Phone 68670 0
+61 3 9341 1500
Fax 68670 0
Email 68670 0
Contact person for public queries
Name 68671 0
Dr Alison Sahhar
Address 68671 0
University of Melbourne
School of Dentistry, Orthodontic Department
720 Swanston Street
VIC 3053
Country 68671 0
Phone 68671 0
+61 3 9341 1520
Fax 68671 0
Email 68671 0
Contact person for scientific queries
Name 68672 0
Dr Alison Sahhar
Address 68672 0
University of Melbourne
School of Dentistry, Orthodontic Department
720 Swanston Street
VIC 3053
Country 68672 0
Phone 68672 0
+61 3 9341 1520
Fax 68672 0
Email 68672 0

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