Radiation dose in severe periodontitis assessment

Key Points

• Fifty patients with generalised severe periodontitis were examined to identify which teeth required radiographic assessment.

• Panoramic radiographs were taken and examined. It was decided that, on average, 4.3 supplementary periapical views would be required for adequate periodontal assessment of all the affected teeth and, if teeth requiring dental radiographic assessment were added, 5.1 supplementary periapical views would be required.

• This paper demonstrates that the effective radiation dose from a series of periapical radiographs of all the affected teeth would, in most cases, have been less than the dose from the panoramic-plus-periapicals approach.

• These conclusions are specific for the equipment and exposure factors used with which, therefore, it is difficult to justify the use of panoramic radiography for periodontal assessment.

• This paper also demonstrates how evidence can be obtained to develop radiographic selection criteria of the periodontal tissues.

Abstract

Objective Radiographic assessment of patients with generalised severe periodontitis may be undertaken with a panoramic view and supplementary periapicals. The purpose of this study was to estimate the effective radiation dose from this form of radiographic assessment, and to compare it with an estimate of the dose from a series of periapicals of all the affected teeth.

Design Cross-sectional observational study.

Setting Departments of Periodontology and Radiology, Glasgow Dental Hospital and School.

Method Fifty consecutive patients with sufficiently widespread advanced periodontitis to require at least seven periapical radiographs were recruited. Following new local guidelines, a panoramic view was taken. The adequacy of the image of every affected tooth and the number of supplementary periapicals required was determined by a panel of four examiners who also calculated the number of periapicals which would have been taken if panoramic radiography had not been available. An effective dose of 0.001 mSv for one periapical and 0.007 mSv for a panoramic view was assumed.

Results The panoramic-plus-periapicals approach delivered an estimated additional effective dose to 86% of patients, in the order of 0.001 – 0.007 mSv.

Conclusions Within the parameters of this investigation, the anticipated effective radiation dose from a series of periapical radiographs of all selected teeth would, for the great majority of patients, have been less than the dose from a panoramic-plus-periapicals approach.

Main

A comparison of two radiographic assessment protocols for patients with periodontal disease. W. M. M. Jenkins, L. M. Brocklebank, S. M. Winning, M. Wylupek, A. Donaldson and R.M. Strang Br Dent J 2005; 198: 565–569

Comment

This study by Jenkins et al. is an important contribution to the evidence guiding clinical decision making. In particular, it sheds light on an area of little clarity — the selection of radiographs for patients with significant levels of periodontal destruction. Selection is a function of risk vs. benefit. The problem is that although the risk of radiography is well described, the benefits are less characterised. Recent guidelines have attempted to produce order from the limited evidence available and these include the FGDP and more recent European guidance.^1,1 Both however, acknowledge the lack of research evidence supporting their recommendations.

Accurate and detailed clinical assessment of periodontitis provides the cornerstone of information leading to the appropriate diagnosis and selection of treatment choices. However, diagnostic quality radiographs are also essential. As the authors point out, radiographic findings that could affect diagnosis and treatment planning include the location and extent of marginal bone loss, the configuration of angular bone defects, root anatomy, furcation involvements, proximity to adjacent teeth and proximity to anatomical structures such as the maxillary sinus. However, one of the strengths of this study is that periodontitis was not viewed in isolation. Indications for radiographs included possible restorative complications such as caries, endodontic problems and inadequate restoration marginal fit. Since assessment of periodontitis is never conducted in isolation, this aspect of the study increases its generalisability (external validity) outside of a purely periodontal setting.

The chief finding from this study is striking – panoramic radiography supplemented by periapical films, taken in order to achieve adequate diagnostic quality, results in a higher effective radiation dose than taking periapicals only of the regions of interest. Of the patients in the study 86% would have received a higher effective radiation dose in this manner which corresponds to an additional 1-7 periapical films per patient (depending on radiographic conditions).

Notice that these findings reflect radiographic best practice, using a careful technique that minimised dosage and maximised the likelihood of achieving a diagnostic quality film. It is interesting that inter-examiner agreement for periodontal diagnosis between all four examiners was 48% and this reflects the real world of interpretation of images. Possibly this value would be much lower with poorer quality images.