JICDRO is a UGC approved journal (Journal no. 63927)
Year : 2010  |  Volume : 2  |  Issue : 3  |  Page : 143-152

The effect of exposure reduction on the diagnosis of caries: An ex vivo comparison of film and a CMOS digital imaging system

1 Department of Biomedical and Diagnostic Sciences, University of Detroit Mercy School of Dentistry, Detroit, Michigan, USA
2 Department of Clinical Dentistry, Midwestern University College of Dental Medicine, Glendale, Arizona, USA

Correspondence Address:
James R Geist
University of Detroit Mercy School of Dentistry, 2700 Martin Luther King, Jr, Blvd, Detroit, MI 48208-2576
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Source of Support: This project was funded by Delta Dental Fund of Michigan grant number 260694, Conflict of Interest: None

DOI: 10.4103/2231-0754.95288

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Objectives: To determine the effect on caries diagnosis of exposure reduction on intraoral digital radiographs compared with optimally exposed film images. Materials and Methods: F-speed film radiographs of 61 extracted molars and premolars were made with optimal exposure parameters. The teeth were radiographed using a complementary metal oxide semiconductor (CMOS) digital system with exposures equal to 50%, 30%, 20%, 10%, and 5% of the film exposure. Five observers, who were permitted to adjust brightness and contrast on the digital images, scored the proximal and occlusal surfaces for the presence of caries using a 5-point confidence scale. Areas under receiver operating characteristic (ROC) curves represented accuracy of caries detection. Sensitivity and specificity were also calculated. The significance level was P = 0.05. Results: All digital images resulted in lower diagnostic accuracy than film images for all lesions (P ≤ 0.036) and for caries in enamel only (P ≤ 0.030). With dentin caries, there were no significant differences between film and any digital radiographs (P ≥ 0.065) except the 5% exposures (P ≤ 0.034). Digital radiographs of 5% of the exposure of film were significantly poorer than all other exposure categories (P ≤ 0.014) except for the 10% exposures for accuracy for all lesion sizes and for dentin lesions only. Exposures at 10% and 20% resulted in lower sensitivity scores for enamel caries, while 50% exposures were associated with the poorest specificity. Conclusions: Exposures of 30% of optimal F-speed film exposure settings appear to balance acceptable levels of accuracy, sensitivity, and specificity for caries detection. Observer-controlled enhancements were ineffective at extremely high and low exposures.

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