A method for the validation of a new calculus detection system.

BACKGROUND Recently, pilot studies from our laboratory have shown that dental surfaces may be discriminated by the analysis of tip oscillations of an ultrasonic instrument, which possesses computerized calculus-detection features. For the evaluation of this smart detection system, its surface recognition qualities are of crucial importance. For in vivo studies, however, it proved to be difficult to verify the subgingival detection results. Therefore, it was necessary to develop a method, which allowed a reliable validation of surface recognition results of this new device. This evaluation method is described here. MATERIALS AND METHODS Thirty extracted human teeth with subgingival calculus were embedded with plaster in a tray. To simulate subgingival pockets, dissected mucoperiostal porcine gingiva was sutured on the teeth. The thus-constructed dentition was mounted into a phantom head. A CCD-cam was attached with an intra-oral X-ray mount to the teeth. The dentist scanned the pockets with the ultrasonic instrument, simultaneously videotaping the scanning path of the supragingival portion of the insert. At the same time, the signals of the modified ultrasound scaler were recorded. After the tooth was removed from the phantom head, the tip of the ultrasound scaler could be repositioned using the video sequences. The actual insert location on calculus or cementum was assessed and compared with the computer signals. The whole procedure was repeated a second time and the reproducibility of the evaluation method was estimated. RESULTS A kappa value of 0.95 was attained for the evaluation method. CONCLUSION The present experimental design allows the in vitro repositioning of an automated dental instrument for the detection of subgingival surfaces on the tooth following an in vitro phantom-head video recording of its intra-oral scanning movements. This method will be used for the verification of in vivo results of a new ultrasound-based surface detection system.