Improving the Quality of Dentistry

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Trial Overview

Periodontal disease is the most common oral disease affecting adults. Effective self-care (tooth brushing and interdental aids) for plaque control and removal of risk factors such as calculus, by periodontal instrumentation (PI), commonly known as a “scale and polish”, are considered necessary to prevent and treat periodontal disease.

A Cochrane review found evidence that psychological interventions resulted in improvements in oral hygiene behaviours but there is a lack of reliable evidence to inform clinicians of the relative effectiveness of different types of Oral Hygiene Advice (OHA) on the prevention of periodontal disease in adults.  Similarly there is mixed evidence on the effectiveness and optimal frequency of PI.  The majority of trials that have been carried out to date have been of poor to moderate quality with few conducted in primary care and a lack of patient centred outcomes and economic analyses reported. 

The NIHR HTA funded IQuaD Trial is being led by the University of Dundee. The Trial is run in collaboration with the Universities of Aberdeen, Edinburgh, Glasgow, Manchester, Newcastle, Kings College, London and NHS Education for Scotland. 

Aims and Objectives

The aim of this study is to compare the effectiveness and cost-effectiveness of theoretically based, personalised oral hygiene advice (OHA) or periodontal instrumentation (PI) at different time intervals or their combination, for improving periodontal health in dentate adults attending general dental practice.

The primary objectives are to test the effectiveness and cost effectiveness of the following dental management strategies:

  1. Personalised OHA versus routine OHA
  2. 12 monthly PI versus 6 monthly PI
  3. No PI versus 6 monthly PI

Trial Design

Participating dentists (63) will be cluster randomised to provide routine (current practice) or theory-based personalised (to the needs of the patient) OHA.   A total of 1877 individual eligible patients have been randomised to no PI, 6 monthly PI or 12 monthly PI (approx. 310 to each group within each cluster of routine or personalised OHA randomised dentists).

In general dental practice both OHA and PI can be delivered by a dentist or by a dental hygienist.  The trial interventions are delivered by the dentist or by the hygienist in line with each dentist’s usual practice.

Routine OHA versus Personalised OHA

  • Routine OHA indicates current practice.
  • Personalised OHA Intervention Training is provided. The content of the advice delivered is personalised according to the dentist’s/hygienist’s assessment of the needs of the patient.

Outcome Measures

  • Gingival inflammation/bleeding on probing at the gingival margin at 3 year follow-up;
  • Oral hygiene self-efficacy at 3 year follow-up: Oral Health Impact Profile-14 (OHIP-14);
  • Net benefits (mean willingness to pay minus mean costs).


1877 participants have been recruited from 63 dental practices across Scotland and the North East of England.  The map identifies the areas where participant recruitment is taking place in dental practices across the UK.


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.


Click here to view our video on Delivering Personalised Oral Health Advice. 


Clarkson, J.E. et al., 2013. IQuaD dental trial; improving the quality of dentistry: a multicentre randomised controlled trial comparing oral hygiene advice and periodontal instrumentation for the prevention and management of periodontal disease in dentate adults attending dental primary care.  BMC Oral Health, 13 (1). 58

Lamont, T., Keightley, A., Clarkson, J., 2013. Accessing the best evidence. Dental Update, 40 (6), pp. 482-486

Worthington, H.V., Clarkson, J.E., Bryan G., 2013. Routine scale and polish for periodontal health in adults. Cochrane Database of Systematic Reviews, (11)

Worthington, H., Clarkson, J. E., Bryan, G., Beirne, P.V., 20132012. The Evidence Base for Oral Health. UK Science and Technology.

Clarkson, J., Worthington, H., 2013. Twenty Years of the Cochrane Collaboration. Journal of Dental Research. Vol. 92, 8:pp. 680-681


Ramsay, C., NIHR HTA IQuaD: A multicentre RCT comparing oral hygiene advice and periodontal instrumentation for the prevention and management of periodontal disease in dentate adults attending dental primary care, Scottish Dental Practice Based Research Network Annual Conference, 9 November 2011

Lamont, T., Dental Clinical Trials, Faculty of General Dental Practitioners - Scottish Study Day, 2 December 2011

Lamont, T., NIHR HTA Dental Trials Update, Faculty of General Dental Practitioners - Scotland Study Day, 7 December 2012

Other Information Sources

For further information, please see -

Joint Chief Investigators

Trial Team

The Co-Chief Investigators are based at the Universities of Dundee and Aberdeen.  The full trial team includes collaborators from the Universities of Manchester, Edinburgh, Newcastle and Glasgow, NHS Education for Scotland and Kings College London.  The multi-disciplinary research team has been established to work alongside a world-wide team of specialist periodontal and Primary Care dentists and members of their teams.  This is to ensure that whilst the Trial design and conduct is of the highest standard, it remains practical and pragmatic.

NIHR Disclaimer

This project is funded by the National Institute for Health Research Health Technology Assessment (NIHR HTA) Programme (project number 09/01/45) 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.





Collaborators and Partners