Reliability Assessment of a Plaque Scoring Index Using Photographs

Objectives: The need to evaluate the reliability of a clinical index before using it as a research tool is clearly recognized. Therefore the aim of this study was to evaluate whether a new calibration method by means of photographs would be useful for assessing the examiners’ reliability in the interpretation of a plaque index. Methods: Nine children were randomly recruited from a public school in Rio de Janeiro, Brazil. Two trained examiners evaluated these children for dental plaque, in a classroom environment, in order to record plaque scores. The children’s teeth were dyed and colored photographs were taken of all tooth surfaces using a camera, mouth mirrors and lip retractors. The photographs were evaluated to select and identify the best visible tooth surfaces, and the final sample consisted of 343 tooth surfaces. One week after the clinical examination, both examiners scored the tooth surfaces from the photographs according to the index used. The intra and inter-examiner agreements were measured by intra-class correlation coefficient (ICC) for individual mean scores and for tooth surfaces scores. Results: The data showed an excellent agreement (ICC >0.80) between clinical and photographic examinations, for both examiners, both for tooth surface and patient analysis. The statistics also demonstrated excellent (ICC >0.80) inter-examiner agreement on clinical and photographic examinations. Conclusion: The method seems to be an effective technique to evaluate the reliability of the plaque index, improving the reproducibility of epidemiological studies.