Trial Review

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Trial registered on ANZCTR


Registration number
Help: Registration number
ACTRN12626001098325p
Ethics application status
Help: Ethics application status
Submitted, not yet approved
Date submitted
Help: Date submitted
17/08/2026
Date registered
Help: Date registered
4/09/2026
Date last updated
Help: Date last updated
4/09/2026
Date data sharing statement initially provided
Help: Data sharing statement date
4/09/2026
Type of registration
Help: Type of registration
Prospectively registered

Titles & IDs
Public title
Short- and long- term clinical effectiveness between different types of computer-aided design/computer-aided manufacturing (CAD/CAM) and conventional orthodontic retainers – a prospective randomised controlled trial
Scientific title
Short- and long- term clinical effectiveness between different types of CAD/CAM and conventional orthodontic retainers in patients following comprehensive orthodontic treatment – a prospective randomised controlled trial
Additional trial identifiers [1] 318193 0
Nil
Universal Trial Number (UTN)
Trial acronym
Related trial records

Health condition
Health condition(s) studied:
Orthodontic relapse following orthodontic treatment 343251 0
Maintenance of lower anterior tooth alignment following orthodontic treatment 343328 0
Condition category
Condition code
Oral and Gastrointestinal 339362 339362 0 0
Other diseases of the mouth, teeth, oesophagus, digestive system including liver and colon

Intervention/exposure
Study type
Interventional
Description of the intervention or exposure
Intervention: Following completion of active orthodontic treatment, participants will undergo placement of a mandibular fixed orthodontic retainer and will be randomly allocated to one of three groups:
1. CAD/CAM 0.026-inch stainless steel fixed retainer (intervention group 1)
2. CAD/CAM 0.018-inch stainless steel fixed retainer (intervention group 2)
3. Conventional multi-stranded stainless steel fixed retainer (intervention group 3)
A standardised lower removable vacuum-formed retainer will also be provided to all participants.

Delivery: The fixed and removable retainers will be provided face-to-face and individually at the Melbourne Dental Clinic by orthodontic registrars under the supervision of specialist orthodontists with appropriate training and experience in fixed retainer placement and post-orthodontic retention. Fixed retainer placement will be completed during a single clinical visit of approximately 60-90 minutes. Participants will be instructed to wear their removable retainer full-time for the first three months, followed by nightly wear for at least 7 hours per night for 24 months. Fixed retainers will be reviewed every six months, with each review visit lasting approximately 15 minutes. Fixed retainers are intended to remain in situ indefinitely. If breakage occurs, the retainer will be repaired or replaced as clinically appropriate. Participants may also elect to have the fixed retainer removed at any time. The intervention is standard for all patients following orthodontic treatment, irrespective of whether they are part of the trial.

Frequency and duration: The retainers will be placed/provided at the completion of active orthodontic treatment. Participants will subsequently attend scheduled follow-up assessments at the following time points: immediately after completion of active orthodontic treatment, followed by 1 months, 6 months, 12 months, 24 months and 5 years, after completing active orthodontic treatment.

Adherence: Fixed retainer integrity will be assessed at follow-up visits. Participants will be instructed on the prescribed wear of the removable retainer, with adherence reviewed during follow-up.
Intervention code [1] 335090 0
Treatment: Other
Description of the comparator or control
Comparator: The control group will receive a mandibular canine-to-canine (3–3) fixed retainer using conventional multi-stranded stainless steel wire, representing standard fixed retention care. A standardised lower removable vacuum-formed retainer will also be provided.

Delivery: The fixed and removable retainers will be provided face-to-face and individually at the Melbourne Dental Clinic by orthodontic registrars under the supervision of specialist orthodontists with appropriate training and experience in fixed retainer placement and post-orthodontic retention. Fixed retainer placement will be completed during a single clinical visit of approximately 60-90 minutes. Participants will be instructed to wear their removable retainer full-time for the first three months, followed by nightly wear for at least 7 hours per night for 24 months. Fixed retainers will be reviewed every six months, with each review visit lasting approximately 15 minutes. Fixed retainers are intended to remain in situ indefinitely. If breakage occurs, the retainer will be repaired or replaced as clinically appropriate. Participants may also elect to have the fixed retainer removed at any time. The intervention is standard for all patients following orthodontic treatment, irrespective of whether they are part of the trial. This statement applies to both the comparator and control groups. Fixed retainer materials and bonding protocols vary among specialist orthodontists according to individual clinical preference, with several established approaches currently in routine use. Importantly, all three fixed retainer protocols included in this study are established and clinically accepted retention strategies.

Frequency and duration: The retainers will be placed/provided at the completion of active orthodontic treatment. Participants will subsequently attend scheduled follow-up assessments at the following time points: immediately after completion of active orthodontic treatment, followed by 1 months, 6 months, 12 months, 24 months and 5 years, after completing active orthodontic treatment.

Adherence: Fixed retainer integrity will be assessed at follow-up visits. Participants will be instructed on the prescribed wear of the removable retainer, with adherence reviewed during follow-up.
Control group
Active

Outcomes
Primary outcome [1] 346564 0
Post-treatment stability
Timepoint [1] 346564 0
Baseline (retainer placement) and scheduled follow-up assessments at the following time points i.e. baseline (retainer placement), then scheduled follow-up assessments at 1 month, 6 months, 12 months, 24 months (primary end points), and 5 years post-retainer placement.
Secondary outcome [1] 466402 0
Fixed retainer failure rate
Timepoint [1] 466402 0
Scheduled follow-up assessments at the following time points i.e. baseline (retainer placement), then scheduled follow-up assessments at 1 month, 6 months, 12 months, 24 months (primary end points), and 5 years post-retainer placement.
Secondary outcome [2] 466403 0
Periodontal health
Timepoint [2] 466403 0
Baseline (retainer placement) and scheduled follow-up assessments at 1 month, 6 months, 12 months, 24 months, and 5 years
Secondary outcome [3] 466404 0
Patient satisfaction
Timepoint [3] 466404 0
Scheduled follow-up assessments at 1 month, 6 months, 12 months, 24 months, and 5 years post-retainer placement.
Secondary outcome [4] 466918 0
Fixed retainer failure rate
Timepoint [4] 466918 0
Scheduled follow-up assessments at the following time points i.e. baseline (retainer placement), then scheduled follow-up assessments at 1 month, 6 months, 12 months, 24 months (primary end points), and 5 years post-retainer placement.

Eligibility
Key inclusion criteria
Patients with good general health aged 12-45 years old at the time of completion of their orthodontic treatment will be invited to participate around 1-2 months prior their expected completion of orthodontic treatment, actual participation begins at the completion of orthodontic treatment. These patients must have had comprehensive fixed or aligner orthodontic treatment, and the presence of all maxillary and mandibular anterior teeth with normal shape and size.

Participation for the trial begins at the completion of orthodontic treatment.
Minimum age
12 Years
Maximum age
45 Years
Sex
Both males and females
Healthy volunteers
No
Key exclusion criteria
Patients with craniofacial disorders/syndromes, lingual appliances, periodontal disease, anterior teeth caries, restorations, hypoplasia or fractures, fluorosis or retreatment.

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Randomisation will be performed using off-site allocation, with the allocation sequence concealed from the treating clinicians and participants until assignment.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
A computer-generated randomisation sequence using block randomisation will be used to allocate participants to the three study groups in a 1:1:1 ratio, ensuring approximately equal group sizes throughout recruitment.
Masking / blinding
Who is / are masked / blinded?



Intervention assignment
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
7/09/2026
Actual
Date of last participant enrolment
Anticipated
18/12/2026
Actual
Date of last data collection
Anticipated
18/12/2031
Actual
Sample size
Target
150
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 322759 0
University
Name [1] 322759 0
The University of Melbourne Orthodontic Fund
Country [1] 322759 0
Australia
Primary sponsor type
University
Name
The University of Melbourne
Address
Country
Australia
Secondary sponsor category [1] 325681 0
None
Name [1] 325681 0
Address [1] 325681 0
Country [1] 325681 0

Ethics approval
Ethics application status
Submitted, not yet approved
Ethics committee name [1] 321196 0
University of Melbourne Central Human Research Ethics Committee
Ethics committee address [1] 321196 0
Ethics committee country [1] 321196 0
Australia
Date submitted for ethics approval [1] 321196 0
14/08/2026
Approval date [1] 321196 0
Ethics approval number [1] 321196 0

Summary
Brief summary
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 152982 0
Prof Marie Cornelis
Address 152982 0
Melbourne Dental School Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 720 Swanston Street Carlton, VIC 3053 Australia
Country 152982 0
Australia
Phone 152982 0
+61 3 9035 8402
Fax 152982 0
Email 152982 0
[email protected]
Contact person for public queries
Name 152983 0
Marie Cornelis
Address 152983 0
Melbourne Dental School Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 720 Swanston Street Carlton, VIC 3053 Australia
Country 152983 0
Australia
Phone 152983 0
+61 3 9341 1000
Fax 152983 0
Email 152983 0
[email protected]
Contact person for scientific queries
Name 152984 0
Marie Cornelis
Address 152984 0
Melbourne Dental School Faculty of Medicine, Dentistry and Health Sciences, The University of Melbourne, 720 Swanston Street Carlton, VIC 3053 Australia
Country 152984 0
Australia
Phone 152984 0
+61 3 9341 1000
Fax 152984 0
Email 152984 0
[email protected]

Data sharing statement
Will the study consider sharing individual participant data?
Yes
Will there be any conditions when requesting access to individual participant data?
Persons/groups eligible to request access:
• Researchers
Conditions for requesting access:
• Yes, conditions apply:
• Requires review on a case-by-case basis by the trial custodian, sponsor or data sharing committee
• Requires a scientifically sound proposal or protocol
• Requires approval by an ethics committee
• Requires a data sharing agreement between data requester and trial custodian or sponsor
What individual participant data might be shared?
• De-identified individual participant data:
• Published results
• Primary outcome(s)
What types of analyses could be done with individual participant data?
• Systematic reviews and meta-analyses
• Studies exploring new research questions
• Studies testing whether findings can be repeated or confirmed
When can requests for individual participant data be made (start and end dates)?
From:
After publication of main results
To:
No end date
Where can requests to access individual participant data be made, or data be obtained directly?
• Email of trial custodian, sponsor or committee: Requests for access to de-identified individual participant data can be made to the Principal Investigator, Professor Marie Cornelis, The University of Melbourne.
Contact email: [email protected]

Are there extra considerations when requesting access to individual participant data?
No


What supporting documents are/will be available?

TypeCitationLinkEmailOther DetailsAttachment
Study protocol    Research Protocol.docx
Informed consent form    (2a) Retention Study - PLS Adult Revised.docx
Informed consent form    (2b) Retention Study - PLS Guardian Revised.docx


Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.