Selecting the optimal threshold for the radiographic diagnosis of interproximal caries

The declining prevalence of dental caries and changes in understanding about the progressive nature of this disease have led to recommendations that new diagnostic criteria be adopted. Selecting the optimum diagnostic threshold requires consideration of the probability of disease, distribution of true and false diagnoses at different test thresholds, and estimates of the consequences of treatment based on these diagnoses. Data from the Veterans Administration Dental Longitudinal Study were used to determine the distribution of true and false diagnoses at progressively more stringent diagnostic thresholds. Estimates of the consequences of treatment provided on the basis of true and false diagnoses were obtained from a randomly selected group of clinicians. The data were combined in a decision analysis to determine the "expected value" of operative treatment at each threshold under varying assumptions about the prevalence of disease, rate of disease progression, and value of treatment. No single diagnostic threshold consistently maximized the benefits of treatment. While patients with a high caries prevalence who experience infrequent recalls would benefit from a diagnostic threshold that includes early lesions, patients with a low caries prevalence who follow good recall schedules should benefit from a more conservative diagnostic threshold.