Objectives: To compare the assessment of demineralised white lesions surrounding orthodontic brackets from images produced with and without polarising filters.
Methods: Thirty teeth with orthodontic brackets and a systematic arrangement of artificially-induced demineralisation were used in this in vitro study. A digital image of each tooth was taken with a FinePix S1 Pro digital camera and Cokin flash with and without the polarising filters. All images were repeated after one week. The images were numbered, recoded in a random order and assessed by a second investigator, who was blind as to the nature of the investigation. The four corners of the bracket were examined and the presence or absence of demineralisation was recorded. This assessment was then compared with the actual demineralisation pattern and the positive and negative predictive values were calculated. Twenty polarised and non-polarised images were randomly chosen and duplicated. Percentage agreement between the first and second assessment of the same slide was calculated.
Results: The positive and negative predictive values were better with the polarised images (0.97 and 0.84) than with the non-polarised images (0.92 and 0.81). The percentage agreement was better with the repeat slides of the polarised images (95%) compared with the non-polarised images (91%).
Conclusion: Images produced with polarising filters were more accurately and reproducibly assessed for demineralised white lesions surrounding orthodontic brackets, than images produced without polarising filters.