Fluorescence tools have shown to be highly valuable for precise diagnosis of caries and other lesions in dentistry. In the form of ultraviolet (UV) headlights and special loupes with high levels of magnification and observational capacity, these instruments can even be used during treatment for a more preventive and minimally invasive treatment strategy. Fluorescence, a type of luminescence, absorbs light of shorter wavelength and re-emits it as longer-wavelength light. This changes the color, for example from blue to red. The fluorescence spectra of carious lesions are typical for fluorescent porphyrins, mainly protoporphyrin IX. A possible source of these porphyrins within carious tissues is bacterial biosynthesis. Streptococcus mutans induces enamel and dentin lesions and modifies the fluorescence in the red and green spectral regions, with a stronger signal in the red region, due to porphyrin gradient signals. This article describes the concept of fluorescence-enhanced theragnosis for removal of caries and preservation of sound dental tissues.