Aim of this study was to test recently recommended cut-off limits for the laser fluorescence based device DIAGNOdent (KaVo) for occlusal caries detection. 248 permanent molars of 94 patients (mean age 19.2 yrs) of a general dental practice were included. After professional tooth cleaning the teeth were examined visually and by the DIAGNOdent device. The extent of occlusal lesions (gold standard) was determined after minimal operative intervention. Upon fissure opening 24 teeth had an enamel caries and 224 teeth revealed dentin caries of which 58 and 166 were up to half or beyond half the dentin, respectively. The optimal cut-off limits based on the highest κ-values (0.51 and 0.54) were > 18 for superficial dentinal caries (D3) and > 37 for deep dentinal caries (D4), respectively. 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 considerable variation of the performance. Recommended cut-offs between 17 to 21 for superficial dentin lesions were in the same order of magnitude (0.48 ¡V 0.51). On the D4 level only the manufacturers cut-off of > 34 achieved the best performance (0.51). According to the κ-values and the area under the ROC curves (D3: Az = 0.903; D4: Az = 0.830) the agreement between validated caries extent and laser fluorescence value is still unsatisfactory.Regarding the limited data base cut-off values for the clinical use of DIAGNOdent should be interpreted cautiously until more in vivo studies are available. Schlagwörter: caries, diagnostics, DIAGNOdent, laserfluorescence