diagnostic value of diagnodent in detecting caries under composite restorations of primary molars

background: direct observation cannot detect caries under restorations; therefore, the aim of this study was to compare the accuracy of radiographs and diagnodent in detecting caries under restorations in primary teeth using histologic evaluation. materials and methods: a total of 74 previously extracted primary molars (37 with occlusal caries and 37 without caries) were used. class 1 cavity preparations were made on each tooth by a single clinician and then the preparations were filled with composite resin. the accuracy of radiographs and diagnodent in detecting caries was compared using histologic evaluation. the data were analyzed by spss version 21 using chi‑square, mc namara statistical tests and receiver operating characteristic curve. the significance was set at 0.05. results: the sensitivity and specificity for diagnodent were 70.97 and 83.72, respectively. few false negative results were observed, and the positive predictive value was high (+pv = 75.9) and the area under curve was more than 0.70 therefore making diagnodenta great method for detecting caries ( p = 0.0001). two observers evaluated the radiographs and both observers had low sensitivity (first observer: 48.39) (second observer: 51.61) and high specificity (both observers: 79.07). the +pv was lower than diagnodent and the area under curve for both observers was less than 0.70. however, the difference between the two methods was not significant. conclusion: diagnodent showed a greater accuracy in detecting secondary caries under primary molar restorations, compared to radiographs. although diagnodent is an effective method for detecting caries under composite restorations, it is better to be used as an adjunctive method alongside other detecting procedures. key words: careis, diagnosis, laser fluorescence, radiography