INTERVAL Dental Recalls Trial

ISRCTN	ISRCTN95933794
DOI	https://doi.org/10.1186/ISRCTN95933794
Protocol serial number	HTA 06/35/99
Sponsor	University of Dundee (UK)
Funder	NIHR Health Technology Assessment Programme - HTA (UK)

Submission date: 18/08/2008
Registration date: 20/08/2008
Last edited: 23/11/2020

Recruitment status: No longer recruiting
Overall study status: Completed
Condition category: Oral Health

Prospectively registered

Protocol

Statistical analysis plan

Results

Individual participant data

Plain English summary of protocol

Plain English summary as of 04/10/2018:
Background and study aims
Traditionally dentists encourage the practice of recommending 6 monthly dental check-ups. There is, however, little information to either support or refute this practice, or to advise either patients or dentists of the best dental recall interval for the maintenance of oral health.
The purpose of this study is to investigate and compare the effect of three different arrangements for the timing of dental check-up recall intervals on oral health.

Who can participate?
Adults 18 years of age or older who have visited their dentist in the previous 2 years and who receive all or part of their care as NHS patients.

What does the study involve?
Participants will be randomly allocated to one of three groups:
Group 1: a fixed, 6 month recall interval.
Group 2: an individualised, recall interval based on the patients risk of dental disease.
Group 3: a fixed, 24 month recall interval.

What are the possible benefits and risks of participating?
The results of this study will provide much needed evidence on the best time interval between dental check-ups in order to improve and maintain oral health.

Where is the study run from?
The study is being organised by staff at the INTERVAL Dental Recalls Trial Office at the Dental Health Services & Research Unit, School of Dentistry, University of Dundee. Research groups from NHS Education for Scotland, ACTA, the Universities of King’s College London, Aberdeen, Edinburgh, Glasgow, Manchester, Birmingham, Leeds, Cardiff, St. Andrews and UCL are also involved. 50 dental practices were recruited (Scotland, England, Wales & Northern Ireland).

When is the study starting and how long is it expected to run for?
Phase 1, (feasibility study) started on 01/08/2009 and Phase 2 (main trial) started on 01/09/2011. Both Phase 1 and Phase 2 are included in the study which is expected to end 28/02/19.

Who is funding the study?
National Institute for Health Research, UK.

Who is the main contact?
Prof Jan Clarkson
j.e.clarkson@dundee.ac.uk

Previous plain English summary:
Background and study aims
Traditionally dentists encourage the practice of recommending 6 monthly dental check-ups. There is, however, little information to either support or refute this practice, or to advise either patients or dentists of the best dental recall interval for the maintenance of oral health.
The purpose of this study is to investigate and compare the effect of three different arrangements for the timing of dental check-up recall intervals on oral health.

Who can participate?
Adults 18 years of age or older who have visited their dentist in the previous 2 years.

What does the study involve?
Participants will be randomly allocated to one of three groups:
Group 1: a fixed, 6 month recall interval.
Group 2: an individualised, recall interval based on the patients risk of dental disease.
Group 3: a fixed, 24 month recall interval.

What are the possible benefits and risks of participating?
The results of this study will provide much needed evidence on the best time interval between dental check-ups in order to improve and maintain oral health.

Where is the study run from?
The study is being organised by staff at the INTERVAL Dental Recalls Trial Office at the Dental Health Services & Research Unit, University of Dundee. Research groups from NHS Education for Scotland, the Universities of Aberdeen, Edinburgh, Glasgow, Manchester and St. Andrews are also involved. The study will be carried out in 44 dental practices across the UK (Scotland, England, Wales & Northern Ireland).

When is the study starting and how long is it expected to run for?
The study started in September 2011 and is expected to run until February 2017.

Who is funding the study?
National Institute for Health Research, UK.

Who is the main contact?
Prof Nigel Pitts
n.b.pitts@cpse.dundee.ac.uk

Contact information

Prof Jan Clarkson
Scientific

INTERVAL Dental Recalls Trial
Dental Health Services Research unit
School of Dentistry
University of Dundee
Level, 9 Dundee Dental School
Park Place
Dundee
DD1 4HN
United Kingdom

ORCID ID	0000-0001-5940-2926
Phone	+44(0)1382 383818
Email	j.e.clarkson@dundee.ac.uk

Study information

Primary study design	Interventional
Study design	Multi-centre, parallel-group, randomised controlled trial
Secondary study design	Randomised controlled trial
Study type	Participant information sheet
Scientific title	INTERVAL Dental Recalls Trial (Investigation of NICE Technologies for Enabling Risk-Variable-Adjusted-Length Dental Recalls Trial)
Study acronym	INTERVAL
Study objectives	Study hypothesis as of 25/09/2018: The principal research question is to investigate whether risk-based recall intervals or a fixed-period 24 month recall are more effective and cost effective in maintaining oral health than the traditional fixed-period 6 month recall. Following successful delivery of a feasibility study from 01/08/2009 to 31/08/2011 and the award of new funding, the main trial is being undertaken during 01/09/2011 to 28/02/2017. HTA extension agreed, current end date is 28/02/19. Previous study hypothesis: The principal research question is to investigate whether risk-based recall intervals or a fixed-period 24 month recall are more effective and cost effective in maintaining oral health than the traditional fixed-period 6 month recall. Following successful delivery of a feasibility study from 01/08/2009 to 31/08/2011 and the award of new funding, the main trial is being undertaken during 01/09/2011 to 28/02/2017.
Ethics approval(s)	Transition to the main trial was approved by Fife and Forth Valley REC on 23/09/2011 (ref: 09/S0501/1)
Health condition(s) or problem(s) studied	Oral health
Intervention	Interventions as of 25/09/2018: In total, 2,288 participants will be recruited in order to retain 1,735 at 4 years. This is a 4-year, multi-centre, parallel-group, randomised controlled comparison of three recall intervals: 6-month fixed-period recall, risk-based recall, and 24-month fixed-period recall. Intervention group 1: 6-month, fixed period dental recall. Participants allocated to this group will attend their dentist at fixed, 6 monthly time intervals for a routine dental check-up. The content of this check-up will remain as per current practice. A recognised definition of a traditional NHS dental check-up is clinical examination, advice, charting including monitoring of periodontal status and report. Intervention group 2: Risk-variable-adjusted-length recall interval. Participants allocated to the risk-based recall interval group will attend their dentist at time intervals determined by the evidence-based process outlined in the 2004 National Institute for Health and Clinical Excellence (NICE) guideline on Dental Recall. The recommended stages in establishing the appropriate recall interval are: a. Establishing the age range b. Consideration of risk variables c. Integration and prediction of recall need d. Discussion e. Review Intervention group 3: 24-month, fixed period dental recall. Participants deemed suitable by their dentist for allocation to this group will attend at fixed, 24 monthly time intervals for a routine dental check-up. The content of this check-up is as described for group 1. Details of Joint Principal Investigator: Professor Nigel Pitts Director: Dental Innovation and Translation Centre (ITC) Kings College London Dental Institute Floor 18, Tower Wing Guy’s Hospital LONDON Nigel.pitts@kcl.ac.uk Tel: 020 7188 8094 Previous interventions: In total, 2,288 participants will be recruited in order to retain 1,735 at 4 years. This is a 4-year, multi-centre, parallel-group, randomised controlled comparison of three recall intervals: 6-month fixed-period recall, risk-based recall, and 24-month fixed-period recall. Intervention group 1: 6-month, fixed period dental recall. Participants allocated to this group will attend their dentist at fixed, 6 monthly time intervals for a routine dental check-up. The content of this check-up will remain as per current practice. A recognised definition of a traditional NHS dental check-up is clinical examination, advice, charting including monitoring of periodontal status and report. Intervention group 2: Risk-variable-adjusted-length recall interval. Participants allocated to the risk-based recall interval group will attend their dentist at time intervals determined by the evidence-based process outlined in the 2004 National Institute for Health and Clinical Excellence (NICE) guideline on Dental Recall. The recommended stages in establishing the appropriate recall interval are: a. Establishing the age range b. Consideration of risk variables c. Integration and prediction of recall need d. Discussion e. Review Intervention group 3: 24-month, fixed period dental recall. Participants deemed suitable by their dentist for allocation to this group will attend at fixed, 24 monthly time intervals for a routine dental check-up. The content of this check-up is as described for group 1. Details of Joint Principal Investigator: Dr Jan Clarkson Dental Health Services Research Unit The Mackenzie Building Kirsty Semple Way Dundee DD2 4BF United Kingdom Tel: +44 (0)1382 420060 Email: j.e.clarkson@cpse.dundee.ac.uk
Intervention type	Other
Primary outcome measure(s)	Primary outcome measures as of 25/09/2018: 1. Health related quality of life measured using an annual, self-administered patient questionnaire. Questionnaire will include a global assessment of quality of life using short form Oral Health Impact Profile, a standardised measure of health outcome (EQ-5D). After discussion and consideration a specially developed measure was not required. Removal of relevant text not done due to a clerical error. 2. Periodontal disease assessed by gingival inflammation/bleeding measured according to the Gingival Index of Loe. All clinical outcomes are measured at 4 years by trained examiners who are blinded to allocation. Current primary outcome measures as of 29/09/2011: 1. Health related quality of life measured using an annual, self-administered patient questionnaire. Questionnaire will include a global assessment of quality of life using short form Oral Health Impact Profile, a standardised measure of health outcome (EQ-5D) and a specially developed, context-specific, health related quality of life measure. 2. Periodontal disease assessed by gingival inflammation/bleeding measured according to the Gingival Index of Loe. All clinical outcomes are measured at 4 years by trained examiners who are blinded to allocation. Previous primary outcome measures included both current outcome measures plus the following point: 2. Caries experience assessed at both the enamel and dentine thresholds using the validated International Caries Detection and Assessment System (ICDAS). The ICDAS criteria measure both early and more advanced stages of caries. For early caries, ICDAS measures the surface changes and potential histological depth of carious lesions by relying on surface characteristics related to the optical properties of sound and demineralised enamel prior to cavitation. All surfaces of all teeth will be examined and the status of each recorded in terms of caries and restorations. This system allows the recording of both preventive and operative care needs. This has been moved to secondary outcome measures following discussion between funders, peer reviewers and principal investigators and is reflected in the approved main trial protocol
Key secondary outcome measure(s)	Secondary outcome measures as of 25/09/2018: 1. Caries experience assessed at both the enamel and dentine thresholds using the validated International Caries Detection and Assessment System (ICDAS). The ICDAS criteria measure both early and more advanced stages of caries. For early caries, ICDAS measures the surface changes and potential histological depth of carious lesions by relying on surface characteristics related to the optical properties of sound and demineralised enamel prior to cavitation. All surfaces of all teeth included will be examined and the status of each recorded in terms of caries. This system allows the recording of both preventive and operative care needs. 2. Plaque measured according to the Silness and Loe Plaque Index, calculus measured according to the Ramfjord Calculus Index and a colour-coded UNC periodontal probe will be used to measure periodontal pocket depth and clinical attachment level. The assessments will be made at 4 years by trained examiners who are blinded to allocation. After discussion it was decided that calculus would be recorded as present or not and that plaque and clinical attachment level would not be measured. This is reflected in the approved main trial protocol. 3. Patient-centred outcomes including dental anxiety, oral health related knowledge, attitudes, and behaviours, use of and reason for use of dental services (including symptoms and pain), and satisfaction with care measured using annual, self-administered questionnaire. Total duration of follow-up: 4 years. 4. Dentist attitude towards the different recall strategies measured using a self-administered questionnaire at month 0 and at 4 years Current secondary outcome measures as of 27/09/2011: 1. Caries experience assessed at both the enamel and dentine thresholds using the validated International Caries Detection and Assessment System (ICDAS). The ICDAS criteria measure both early and more advanced stages of caries. For early caries, ICDAS measures the surface changes and potential histological depth of carious lesions by relying on surface characteristics related to the optical properties of sound and demineralised enamel prior to cavitation. All surfaces of all teeth will be examined and the status of each recorded in terms of caries and restorations. This system allows the recording of both preventive and operative care needs. 2. Plaque measured according to the Silness and Loe Plaque Index, calculus measured according to the Ramfjord Calculus Index and a colour-coded UNC periodontal probe will be used to measure periodontal pocket depth and clinical attachment level. The assessments will be made at 4 years by trained examiners who are blinded to allocation. 3. Patient-centred outcomes including dental anxiety, oral health related knowledge, attitudes, and behaviours, use of and reason for use of dental services (including symptoms and pain), and satisfaction with care measured using annual, self-administered questionnaire. Total duration of follow-up: 4 years. 4. Dentist attitude towards the different recall strategies measured using a self-administered questionnaire at month 0 and at 4 years Previous secondary outcome measures included points 2 to 4 only.
Completion date	28/02/2019

Eligibility

Participant type(s)	Patient
Age group	Adult
Lower age limit	18 Years
Sex	All
Target sample size at registration	2288
Total final enrolment	2372
Key inclusion criteria	Adult patients 18 years of age or older who are dentate, have visited their dentist in the previous 2 years, and receive all or part of their dental care as an NHS patient.
Key exclusion criteria	Patients for whom periodontal probing is contraindicated or who have a medical condition indicating increased risk of bleeding (e.g., history of bacterial endocarditis, bleeding disorder, immuno-compromised).
Date of first enrolment	27/07/2010
Date of final enrolment	31/07/2014

Locations

Countries of recruitment

United Kingdom
Scotland

Study participating centre

Dental Health Services Research Unit

Dundee
DD1 4HN
United Kingdom

Results and Publications

Individual participant data (IPD) Intention to share	No
IPD sharing plan summary	Not provided at time of registration
IPD sharing plan

Study outputs

Output type	Details	Date created	Date added	Peer reviewed?	Patient-facing?
Results article	results	01/11/2020	23/11/2020	Yes	No
Protocol article	protocol	07/08/2018	10/09/2019	Yes	No
Participant information sheet	Participant information sheet	11/11/2025	11/11/2025	No	Yes
Study website	Study website	11/11/2025	11/11/2025	No	Yes

Editorial Notes

23/11/2020: Publication reference and total final enrolment number added.
10/09/2019: Publication reference added.
04/10/2018: The following updates were made:
1. The plain English summary was updated
2. The recruitment start date was changed from 01/08/2009 to 27/07/2010
25/09/2018: The following changes were made to the trial record:
1. The trial website was added
2. The contact information was updated
3. The hypothesis was updated
4. The participant information sheet was added
5. The interventions were updated
6. The outcome measures were updated
7. The overall trial start date was updated from 01/09/2011 to 01/08/2009
8. The overall trial end date was updated from 28/02/2017 to 28/02/2019
9. The recruitment start date was updated from 01/09/2011 to 01/08/2009
10. The recruitment end date was updated from 28/02/2017 to 31/07/2014
11. The postcode of the trial participating centre was updated