Research project

NIHR HTA INTERVAL Dental Recalls Trial

Investigation of NICE Technologies for enabling risk-variable-adjusted-length dental recalls trial

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Start date

February 2017


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 for adults. The NIHR HTA funded INTERVAL Trial is being led by the University of Dundee and aims to add to the existing evidence base. The Trial is run in collaboration with other universities including the Universities of Aberdeen, St Andrews, Glasgow, Edinburgh, Birmingham, Cardiff, Manchester, Leeds, King’s College, UCL Eastman Dental Institute and NHS Education Scotland.

The Trial is also supported by other organisations involved in primary care research and local research networks all over the UK.

The results of this Trial will provide much needed evidence on the best time interval between dental check-ups in order to improve and maintain adult oral health in the most cost effective way.

Aims and Objectives

The aim of this study is to evaluate the effectiveness and cost effectiveness of three dental recall strategies by assessing their impact on maintaining adult oral health. The comparisons are:-

  • 6 month recall interval
  • Risk based recall interval based on the patient's risk of dental disease
  • 24 month recall interval

Trial Design

The research will be carried out in 53 general dental practices across the UK operating in a wide range of different circumstances and in fluoridated or non-fluoridated areas. A total of 2288 participants will be recruited to the Trial and randomised to one of the three comparison arms. The 24 month recall arm has been included and participants are potentially randomised to this arm only when considered suitable by their dentist.

Outcome Measures

The primary outcome is measurement of disease (periodontal and caries) assessed at four years by blinded assessors.

Secondary outcomes - patient quality of life, attitudes, knowledge and behaviour; service provider attitudes and costs are measured using questionnaires at baseline and annually during the four years of follow up.


The results of the Trial will be published as widely as possible in academic and professional dental journals as well as the popular press as an aide to decision making by policy makers, dental practitioners and patients. 

NIHR Disclaimer

This project was funded by the National Institute for Health Research Health Technology Assessment (NIHR HTA) Programme (project number 06/35/99) and will be published in full in Health Technology Assessment.  The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the HTA programme, NIHR, NHS or the Department of Health.



Related groups

School of Dentistry

Project type

Research project