Editor—Sheldon et al show a gradual reduction in the number of wisdom teeth extractions, which they propose indicates a diffusion of guidance from the National Institute for Clinical Excellence (NICE) into clinical dental practice.1 The first figure in our response on bmj.com shows the annual number of courses of treatment that included at least one extraction of the third molar in the General Dental Service in Scotland.2 This figure corresponds to the presentation of data in figure 1 of Sheldon et al's paper.1
The raw number of claims per year masks some underlying trends in the data that are revealed by weighting the data by the total number of claims made in the General Dental Service over this period and by disaggregating the data into those wisdom tooth extractions that require a surgical procedure and those that do not.
The figure shows the number of surgical and non-surgical third molar treatments per
Figure 1.
Numbers of surgical and non-surgical third molar treatments and general anaesthetic treatments per 1000 claims in Scottish General Dental Service. Third molar treatment=at least one type of extraction provided in course of treatments; 3m surgical=extractions requiring division of roots or crown; 3m non-surgical=extractions not requiring division of roots or crown; GA=at least one treatment with general anaesthesia (24(A)) provided in course of treatments
1000 claims in the Scottish General Dental Service, as well as the number of general anaesthetic treatments per 1000 claims in the Scottish General Dental Service (from the Management Information and Dental Accounting System (MIDAS) database, which is used to process, authorise, and store all claims for the General Dental Service in NHS Scotland).
The rate of surgical and non-surgical extractions varies around a constant rate until the end of 1998, when the rate of nonsurgical extractions dropped sharply, which is inconsistent with a pattern of guideline implementation by diffusion.
New guidance for the administration of general anaesthesia by dentists in the United Kingdom was issued by the General Dental Council and took effect on 10 November 1998.3 The reduction in the rates of non-surgical extractions coincides with the change in advice from the dental council to dentists.
Although the evidence in the figure does not establish a causal relation between general anaesthetic treatments and wisdom teeth extractions, it does provide some preliminary evidence that the regulatory framework within which general dental services are provided can affect clinicians' behaviour.
We thank Stephen Goold and Alison Simpson, NHS National Services Scotland, for their comments.
Funding: The Dental Health Services Research Unit is funded by the Chief Scientist Office of the Scottish Executive and is part of the MRC Health Services Research Collaboration. This letter expresses the authors' views, which are not necessarily shared by the Scottish Executive.
Competing interests: None declared.
References
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