Sir,- We enjoyed reading the paper by Davenport et al (BDJ 2003, 195: 87) and are prompted to write following the increasing publicity of the concepts of minimal intervention dentistry (MI) and the examination of the clinical needs of new dental students in Birmingham. The treatment needs of the students were generally low, but a significant number needed large restorations, mainly of occlusal cavities which needed restorative treatment well beyond the concept of MI.

So what is the relevance of all this? By definition minimal intervention with all the benefits of preservation of tooth tissue requires detection of disease at a very early stage and this implies more frequent and high quality examinations with the appropriate use of all the current optical radiographic and electronic aids now available to us. The paper mentioned above makes the point that we have no good evidence on which to base selection of a review interval and that we have no clear outcome measure of the value of any selected interval. The preservation of hard tooth tissue in a functional state seems a desirable endpoint as this is likely to reduce the amount of subsequent complex treatment.

Numerically our student group is likely to need a low number of restorations but the likely complexity of this small number of restorations implies a high cost to the community in the long term. As the most recent article reviewed in the paper is eight years old, treatment concepts have changed during this time, as the reviewer, Derek Richards, comments. It would seem therefore very ill advised to make changes to advice on review intervals based on the work available. Surely a large-scale trial using various review/ treatment/preventive philosophies is long overdue. We must be very careful at present not to make changes based on a politically correct view that less reviews mean less dentistry in the long term or that prevention is an alternative to treatment.

Dental health is surely a combination of prevention and effective treatment done at the earliest stage possible to achieve the desired result. Although risk factors are as yet not fully understood we already know enough to tailor a review programme to risk groups in relation to most dental diseases and to feed this into a trial of review intervals. We hope this letter may stimulate debate on setting up such a trial which is at the very centre of our professional work and its development in the future.

The authors of the paper respond: We concur with what appears to be the key issue raised in the letter which is the need for further high quality research on which to base recall intervals for routine dental checks. However, as pointed out in the conclusions of the paper, research of this nature is very difficult to conduct and must be underpinned by appropriate methodological approaches and incorporate clinical outcomes of relevance to professionals and patients.

A point made by R. F. Mosedale and F. J. T. Burke is that treatment concepts have changed considerably since the date of the most recent paper in the review. However, a key challenge in assessing the effectiveness of dental checks is to clearly distinguish between the effectiveness of dental checks and that of treatment. Evaluation of existing literature in this field is hampered by a lack of consistent outcome measures.

The suggestion of 'the preservation of hard tooth tissue in a functional state' may represent such an outcome variable. However standard outcome measures agreed by the fields of dental caries, periodontal disease, soft tissue disease and orthodontics need to be developed and applied consistently in prospective research in order to facilitate comparison between different pieces of research in different settings. In addition the input of patients in the development of research questions and outcome measures has been neglected in the past and needs to be incorporated in any future research.

The point that no evidence does not justify less preventive dentistry is well made. I consider the review clearly states that there is no evidence either to support or to refute a policy of six monthly dental checks. The question 'what is an optimal dental recall interval?' does not as yet have an answer. Policy needs to be informed by either primary research comparing different recall intervals or the use of epidemiological evidence concerning risk factors and disease progression in order to base recall intervals on an individual's risk of oral disease.

C. Davenport, K. Elley

Birmingham