Lustre changes on teeth. The use of laser beams for comparative studies in vivo

An instrument for studies of lustre changes on teeth in vivo was constructed and evaluated. The equipment was based on a helium-neon gas laser, a coordinate screen and a photocell. The intensity of light reflected from incisors of ten test subjects was measured before and after brushing with different dentifrices. The investigation showed that the instrument was useful for measuring intensity differences of laser light reflected from teeth. The intensity was found to vary within wide limits from teeth of different persons. During a test period of 70 days only few lustre changes caused by dentifrices were registered.