Condition category
Oral Health
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Following orthodontic brace treatment the teeth are held in their new position by orthodontic appliances called retainers. One type of retainer is called a bonded retainer which is a small metal wire glued behind the front teeth. This study is looking at the use of two different types of bonded retainer to find out which is better: one that is shaped by the orthodontist, or one that has been made from a mould of the teeth by a computer. The study looks at which holds the teeth in their new position the best, which patients prefer and which is the most cost effective.

Who can participate?
Participants who have undergone a course of orthodontic treatment and who now require a retainer

What does the study involve?
Participants are randomly allocated to one of two groups to be treated with either a Memotain bonded retainer or an Ortho FlexTech bonded retainer. Participants are followed up over a 5-year period to determine the effectiveness of the retainers at maintaining the stability of the teeth after orthodontic treatment.

What are the possible benefits and risks of participating?
The benefit to patients is that they are followed up for longer than normal (5 years). The study will help to show the best type of retainer for certain patients. The current research suggests there are no associated risks with wearing retainers.

Where is the study run from?
1. Leeds Dental Institute (UK)
2. St Luke's Hospital (UK)
3. Beverley Orthodontic Centre (UK)

When is the study starting and how long is it expected to run for?
September 2017 to September 2025 (updated 12/10/2018, previously: September 2023)

Who is funding the study?
1. Investigator initiated and funded
2. National Institute for Health Research (NIHR) (additional funding) (UK)

Who is the main contact?
1. Adam Jowett
2. Simon Littlewood

Trial website

Contact information



Primary contact

Mr Adam Jowett


Contact details

St Luke's Hospital
Little Horton Lane
United Kingdom



Additional contact

Mr Simon Littlewood


Contact details

St Luke's Hospital
Little Horton Lane
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number

Protocol Number: DT16/86705, IRAS Number: 185443, REC Number 16/YH/0463.

Study information

Scientific title

CAD/CAM nitinol bonded retainer versus a chairside bonded retainer: a multicentre randomised controlled trial


Study hypothesis

Null hypothesis: There is no significant difference in stability, survival rate, patient satisfaction, and cost-effectiveness between using a CAD/CAM nitinol bonded retainer (Memotain) and a chairside bonded retainer (Ortho FlexTech).

Ethics approval

Yorkshire & The Humber - Bradford Leeds Research Ethics Committee, 07/07/2017, REC ref: 16/YH/0463, protocol number: DT16/86705

Study design

Multicentre prospective two-arm parallel-group randomised controlled trial with a 1:1 allocation

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details to request a patient information sheet


Orthodontic relapse


Simple randomisation will be used to allocate patients to one of the two groups. The randomisation website: will be used to allocate patients to treatment group 1 or group 2. Block sizes of 2, 4 and 6 will be used.

Group 1: Memotain bonded retainer
Group 2: Ortho FlexTech bonded retainer

Patients are followed up to determine the efficacy of a CAD/CAM nitinol bonded retainer (Memotain) compared with a chairside bonded retainer (Ortho FlexTech) at maintaining the stability of the upper and lower arches after orthodontic treatment.

Intervention type



Drug names

Primary outcome measure

Stability measured by changes in Little's Irregularity Index, and the width of the upper and lower dental arches measured by inter-canine and inter-molar width. In extraction cases, the trialists will also assess whether or not the extraction space re-opens. These measurements will be carried out on orthodontic study models taken at the debond appointment, and the 6 month, 1 year, 2 year and 5 year review appointments.

Secondary outcome measures

Assessed at the 6 week, 6 month, 1 year, 2 year and 5 year review appointments:
1. The survival rate of each retainer type
2. The patient satisfaction with each retainer type

Assessed at the 1 year and 5 year review appointments:
1. The cost-effectiveness of each retainer type

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

Each subject will:
1. Have undergone a course of upper and lower fixed appliance orthodontic treatment with satisfactory correction of the presenting malocclusion, where the treating clinician feels that retention is required
2. Have a full and normal complement of teeth in the upper and lower labial segments (incisors and canines) with these teeth being of normal size and shape
3. Brush their teeth at least twice per day
4. Be in good health
5. Be willing and able to comply with the trial regime
6. Have given written informed consent

Subjects may:
1. Have received treatment at any of the research sites
2. Have had dental extractions (premolar or molar) or a non-extraction approach
3. Have had other orthodontic treatment (e.g. removable or functional appliances) as part of their orthodontic treatment
4. Have undergone adjunctive surgical treatment, whether minor oral surgery to expose a tooth or orthognathic surgery to correct the position of the jaws

Participant type


Age group




Target number of participants

100 patients (50 patients per arm)

Total final enrolment


Participant exclusion criteria

Subjects with:
1. Nickel allergy
2. Cleft palate and/or other severe facial deformity
3. Poor periodontal health including the presence of supragingival or subgingival calculus or periodontal pocketing greater than 3.5mm as determined by a basic periodontal examination (BPE) probe
4. Gross or uncontrolled caries
5. Prosthodontic requirement in the upper or lower arch at end of treatment
6. Restorations on the palatal/lingual surfaces of upper or lower incisors or canines
7. A starting malocclusion requiring extreme transverse correction

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Leeds Dental Institute (University Dental Hospital)
The Worsley Building Clarendon Way
United Kingdom

Trial participating centre

St Luke's Hospital (District General Hospital)
Little Horton Lane
United Kingdom

Trial participating centre

Beverley Orthodontic Centre (Specialist Orthodontic Practice)
114 Norwood
HU17 9HL
United Kingdom

Sponsor information


Leeds Dental Institute

Sponsor details

Worsley Building
Clarendon Way
United Kingdom
+44 (0)113 3434897

Sponsor type

Hospital/treatment centre



Funder type


Funder name

Investigator initiated and funded

Alternative name(s)

Funding Body Type

Funding Body Subtype


Funder name

National Institute for Health Research (NIHR) (additional funding)

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

National government


United Kingdom

Results and Publications

Publication and dissemination plan

Planned publication in a high-impact peer reviewed journal in late 2020.

IPD sharing statement
The datasets generated and/or analysed during the current study will be included in the subsequent results publication.

Intention to publish date


Participant level data


Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

11/12/2019: The following changes have been made: 1. The recruitment end date has been changed from 17/10/2019 to 05/07/2019. 2. The overall trial end date has been changed from 11/09/2025 to 04/07/2025. 3. The total final enrolment number has been changed from 65 to 63. 18/10/2019: The following changes were made to the trial record: 1. The recruitment end date was changed from 11/09/2019 to 17/10/2019. 2. The intention to publish date was changed from 11/09/2026 to 11/10/2020. 3. The total final enrolment was added. 12/10/2018: The following updates were made: 1. The recruitment end date was updated from 11/09/2018 to 11/09/2019 2. The overall trial end date was updated from 11/09/2023 to 11/09/2025 3. The intention to publish date was updated from 31/12/2020 to 11/09/2026