Diagnostic laser DIAGNODENT – detects initial stadium of caries. It detects initial lesions in hard tissue of teeth. That lesions concern demineralization focuses, changes in enamel and dentine, initial carious lesions like carious spots on smooth surfaces and in furrows. The way of acting is following: laser sends a ray in the direction of a tooth, then fluorescence measured in scale from 1 to 99 occurs in carious changed tissues. In this way we are able to detect caries before carietic defect appearance.