This paper on quantitative light-induced fluorescence (QLF) covers the main developments, physical principles, and current application areas of this noninvasive opticalmethod for caries detection. Until now, QLF has mainly been used to detect and monitor initial carious lesions on smooth surfaces, whereas few studies have tried to assess its performance on occlusal pits and fissures. Since it is technically difficult to image proximal lesions, the use of QLF for detecting proximal lesions does not seem very promising from today's point of view. There can be no doubt that the method's great potential lies in the longitudinal observation of in vitro, in situ and in vivo demineralization and remineralization processes. Keywords: QLF, fluorescence, dental caries, diagnosis