Diagnosis of approximal caries: Bite-wing radiology versus the Ultrasound Caries Detector. An in vitro study

Objectives. We sought to examine the validity, sensitivity, and specificity of bite-wing radiographs and a high-frequency sound wave device (the Ultrasound Caries Detector) used to detect caries on contacting approximal surfaces. Methods. A total of 36 extracted premolars and molars were first visually examined for the presence of caries; then a probe was used. Twelve models were prepared, each containing 3 teeth with 2 approximal surfaces and 2 contacted surfaces (of adjacent teeth). Bite-wing radiographs were taken and evaluated for proximal caries lesions. A high-frequency sound wave (ultrasound) device called the Ultrasound Caries Detector was also used to detect caries. Examinations were repeated after I week. Teeth were then sectioned and viewed under a stereomicroscope at 20 x magnification, with which the true interproximal caries diagnosis was validated. The receiver operating characteristic curves were computed to establish the accuracy of the observer data. Results. The efficacy of the ultrasound diagnostic device for cavitated carious lesion detection was assessed by determining its specificity and sensitivity, 1.0 for each, in comparison with those of bite-wing radiography, 0.92 and 0.90, respectively (P < .001). The mean receiver operating characteristic value for the area under the curve was 0.934 with bite-wing radiography and 1 with the ultrasound diagnostic device. Conclusions. Under in vitro conditions, the ultrasound diagnostic device had a higher sensitivity and specificity, in terms of the detection of approximal carious lesions, than bite-wing radiographs.