NIR is replacing x-rays in dentistry

Dental X-rays expose patients to radiation, require time to process and can only “see” a limited amount inside the mouth. Optical coherence tomography (OCT) using NIR light is being used to create high-resolution, 3-D images of teeth. Daniel Fried, from the University of California San Francisco’s School of Dentistry’s Division has developed this application.

“The field is strongly moving in the direction of what we call minimally invasive dentistry,” said John Featherstone, dean of the School of Dentistry, “and the technologies being developed by Dan’s team are a key part of that philosophy.”

OCT can successfully be applied to dentistry for detecting damaged areas, or lesions, in teeth. The researchers showed that the technique was as good or better than X-rays for the early diagnosis of tooth decay.

“Tooth enamel is almost completely transparent in the near-infrared,” Fried said. “We showed that you could take an OCT image of a lesion and tell how severe it is.” Previously the only option was to extract the tooth and cut it open for closer inspection.

Fried and his collaborators also have shown that OCT is useful for monitoring cavities while they are healing.

“Dental decay isn’t like cancer. You can actually treat it, arrest it and even reverse it,” Fried said. “If you spot the lesions early enough, you can treat them with fluoride and re-mineralize them, and you can measure this with OCT. It gives the clinician a way of telling whether the chemical intervention is working.”

While widespread in other medical fields, OCT is just beginning to make its way into dental offices.

“It’s very new technology,” Fried said. “The first commercial system was only introduced this year.”

More recently, Fried’s research has focused on identifying the wavelengths of NIR light that are ideal for screening “hidden” cavities in the pits and fissures of posterior teeth, which are difficult to detect in their early stages using conventional radiography techniques.