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

Objective: 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 1 week. Teeth were then sectioned and viewed under a stereomicroscope at 20x 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.