Diagnodent laser cavity detection is a quick, simple, completely painless way to check your teeth for hidden decay and cavities. After cleaning your teeth, the Diagnodent laser is used to scan your teeth. The laser emits a harmless beam of fluorescent light into your mouth. The light bounces back to the laser diode. Healthy teeth reflect little to no fluorescent light while decay and cavities reflect larger amounts. The Diagnodent laser is attached to a base, which reads the fluorescence and reflects it in a number. The higher the number displayed on the base, the greater the amount of decay. The laser also emits a noise when it detects decay.