The leading paradigm of dentistry had been focused on the rehabilitation treatment that identifies active caries, manages them surgically, and restores their original functions. However, changes in the external environment including the current disease prevalence require dentistry to have a paradigm shift. The new paradigm suggests the detection of caries in their earlier stages over the visual diagnosis of cavities, and the reversal of the incipient caries by non-surgical approach. For this to be achieved, a high-technology detection device recognizing changes in the earlier stages which can not he visually observed is needed. Development of early caries detection device has recently become a major issue in preventive dentistry on account of this need, and QLF(Quantitified Light induced Fluorescence) conspicuously stands out among the newly released devices. In this study, the fundamental concept of QLF(Quantitified Light induced Fluorescence) and the possible clinical applications of the earlier intraoral camera model as well as the recently designed digital camera model will be discussed.