When altered tooth substance is exposed to a specific light wavelength, it emits fluorescent radiation. This radiation is detected and analysed. A specific amount of light energy is supplied by the light probe that contacts and enters the tooth surface. If fluorescent light arises in the case of a pathological change, it is evaluated. At a fissure, careful scanning is required since this allows very small defects to be detected. By moving the probe slightly back and forth over the base of the fissure, the detection sensitivity can be increased and the location of maximum florescence can be identified.

Using the DIAGNOdent pen has advantages over minimally invasive therapy. Very small invisible changes up to a depth of 2 mm can be identified in the tooth substance and treated. The values of the DIAGNOdent pen are not an automatic green light. When interpreting the values, other caries risk factors must be taken into consideration such as the caries history, frequency of sugar intake, presence of caries bacteria, and saliva production. In numerous clinical studies, the thresholds of the DIAGNOdent pen corresponded with actual caries. A diagnosis based on the values of the DIAGNOdent pen together with the caries risk factors enable caries to be identified in a timely manner or whether the tooth substance is healthy. The DIAGNOdent pen is excellent for determining progression. In many cases in which a definitive diagnosis cannot be made, a non-invasive treatment such as fluoridation. The progression can be observed in regular checkups.