The most commonly used technology is Light Induced Fluorescence Technology (LIFT); it detects bacteria on the surface of the tooth by illuminating it with violet light. They operate by shining a low intensity laser or light-emitting diode (LED) light on to the tooth. Because bacteria in dentin infected by caries leave behind metabolic products such as Porphyrins, an exposed cavity that is illuminated by violet light will show a red fluorescence. The use of LIFTs has allowed practitioners to identify and monitor caries more effectively than before. It represents a significant improvement over more primitive methods such as bitewing digital radiography and visual identification of caries. Dental radiographs can detect interproximal lesions, but only after they have demineralized at least 50% of the outer enamel shell. Visual examination looks at the surface of the tooth but most early lesions begin and grow beneath the tooth’s surface.
LIFTs like ACTEON’s SOPROLIFE™ emit a blue LED light. When this light encounters carious regions, the tooth gives off a red fluorescence. An image of the tooth is then projected onto a screen so that both the practitioner and patient can see the image.