A research team led by Masaki Kanbara, a professor of dental health at Osaka Dental University, has developed a diagnostic device that reportedly allows dentists to detect tooth decay before it becomes visible to the naked eye.

Kanbara presented the results of the research to the Japanese Society for Dental Health at a recent meeting in Osaka.

The tooth decay diagnosis, developed jointly with scientists from dental care products maker Lion Corp. and Indiana University, makes use of the characteristics of fluorescence on the surface of tooth enamel.

Tooth decay is caused by bacteria that eat into the enamel and eventually provoke decalcification of the tooth.

By shining a green light on a tooth, Kanbara said, the diagnostic machine is able to pinpoint tooth decay through color differentiation.

While the healthy part of the tooth reflects a yellowish color when cast in the green light, there is little light reflection from the decalcified part and the tiny cavity appears dark.

The greater the decalcified area, the darker it appears on the diagnostic screen.

"This is the first time that we are able to know there is tooth decay even though we can't see it with our eyes," Kanbara said.

He said the entire diagnosis takes several minutes and that doctors will be able to determine the area and depth of decay through image analysis.

Kanbara said it is much easier to catch tooth decay through the early decay diagnostic device than through the laser technique currently being developed by some scientists.

According to Kanbara, researchers are now studying the problem of treating the decay after it is detected by the device.

"We are beginning to understand that we can cure tooth decay by applying fluorosis to the decalcified part of the tooth," he said.