Comparative studies of modern methods for caries detection and quantification

Sammanfattning: In clinical dentistry proper treatment of caries lesions is highly dependent on diagnostic accuracy. Aim The present dissertation aimed at the evaluation and comparisons between several modem methods for caries detection and quantification. Methods The employed methods for detection and quantification of caries lesions may be divided into two categories, namely laser fluorescence based methods and radiographic methods. Laser fluorescence The performance of the DIAGNOdent device was studied in vitro with respect to its validity and reliability on quantification of both occlusal caries and smooth surface caries. The diagnostic accuracy of DIAGNOdent on occlusal caries detection was compared with that of film radiography using Receiver Operating Characteristic (ROC) analysis. A comparison was also performed between DIAGNOdent and Quantitative Laser/Light induced Fluorescence (QLF), a well established fluorescence-based technique, for quantification of smooth surface caries. Furthermore, an in vivo study on QLF was carried out concerning its reproducibility and repeatability. Radiography Under the part of radiographic methods, a new color scale was developed that may improve visual perception as compared to the conventional gray scale and thereby improve caries detection. The new color scale was constructed by taking into consideration both physical properties of colors and psychological properties of the human visual system. Color-coded radiographs were compared with digital radiographs employing the so called perceptibility curve test. Then, color-coded radiographs were applied to the detection of approximal caries lesions, and the diagnostic accuracy of the colored radiographs was compared with that of black-and white radiographs as well as with the DIAGNOdent technique. An additional modem radiographic method that was included in the present research work was Tuned Aperture Computed Tomography (TACT®), which is a tomosynthetic technique. By generating a series of cross sectional images of an object and then combine them, the third dimension may be presented with the TACT® technique, which overcomes the drawback of conventional radiography that displays the three dimensional object in two dimensional images. TACT® imaging was used to assess occlusal caries detection and was compared with film radiography employing ROC analysis. Results In vitro studies of the DIAGNOdent method on occlusal and smooth surface caries diagnosis showed that it is a reliable method in terms of both reproducibility and observer agreement. DIAGNOdent had a good correlation with histological examinations and had a higher diagnostic accuracy than film radiography on occlusal caries detection indicating that DIAGNOdent may be a very helpful tool for occlusal caries detection and quantification. For smooth surface caries quantification, QLF had a higher correlation with mineral loss as compared to DIAGNOdent. A clinical reproducibility and repeatability study showed that QLF had an extremely high correlation coefficient between and within examiners. Thus, QLF proves to be a suitable method for longitudinal studies of mineral changes in caries lesions. Color-coded radiographs demonstrated a certain advantage over black-and-white radiographs based on the perceptibility curve test. However, this advantage did not result in a significant difference when applied to approximal caries detection. Here, perceptual leaming when observers were confronted with a new type of radiographs may have played an important part. TACT® had significantly higher diagnostic performance on occlusal caries detection as compared to film radiography. Conclusion It may be concluded that all the above modem methods have their own specific advantages over conventional methods. If properly applied and correctly interpreted these techniques should improve caries diagnosis and, therefore, the selection of proper treatment.