Comparison of different DIAGNOdent cut-off limits for in vivo detection of occlusal caries

This study tested recently recommended cut-off limits for the laser fluorescence based device DIAGNOdent (KaVo) for detection of occlusal caries. Two hundred and forty-eight permanent molars from 94 patients (mean age 19.2 years) of a general dental practice were included. After professional tooth cleaning, the teeth were examined visually and by the laser fluorescence method. The extent of occlusal lesions (gold standard) was determined after minimal operative intervention. Upon fissure opening, 24 teeth had enamel caries and 224 teeth revealed dentin caries, of which 58 and 166, respectively, were up to or beyond half the dentin. The optimal cut-off limits based on the highest kappa-values (0.51 and 0.54) were > 18 for superficial dentinal caries (D3) and > 37 for deep dentinal caries (D4). The comparison with DIAGNOdent cut-offs given by the manufacturer (n = 4) and those based on clinical trials with in vivo validation (n = 4) and in vitro studies with histological validation (n = 3) revealed a considerable variation in performance. Recommended cut-offs between 17 and 21 for superficial dentin lesions were in the same order of magnitude (0.48-0.51). On the D4 level, only the manufacturer's cut-off of > 34 achieved the best performance (0.51). According to the highest kappa-values and the area under the ROC curves (D3: A(z) = 0.903; D4: A(z) = 0.830), the agreement between the extent of validated caries and laser fluorescence value is still unsatisfactory.