Imaging Cavities in 3-D

Originally Published MDDI November 2004

R&D DIGEST

Imaging Cavities in 3-D

Maria Fontanazza

A new imaging technique may be able to detect cavities before they begin causing a patient pain. Scientists from Glasgow, UK, have found a method that generates a three-dimensional image of a tooth that provides more information than traditional x-rays do.

This technique enables us to see an image of the whole of the tooth by building up optical slices, says John Girkin, MD, associate director at Glasgow's Institute of Photonics at the University of Strathclyde. “There's no other way, at the moment, of building a 3-D image of the tooth.”
Scientists applied a method that was used in the past to obtain optical sections of microscopic samples for research. Until now, it had never been directly used for a medical application. “It has not been applied to macroscopic samples before, and definitely not teeth,” says Girkin.

Cavities are a result of enamel breakdown and mineral loss, caused by acid production. By the time any lesions are seen, it's usually too late. The new technique produces image slices that are put together to form a three-dimensional picture, allowing scientists to see the tooth's structure and any defects, such as mineral loss. It also enables imaging between two teeth, whereas x-rays don't provide depth information, says Girkin.

Although there are other techniques that use fluorescence technology to identify decay, they don't catch it early enough, according to Girkin. “Generally, they are looking at a disease that the dentist will need to drill and fill,” he says. “Our aim is to get to the tooth before this is required.”

A grid is placed in front of a structured infrared light that is shined on the tooth, and a camera is placed on the other side, taking sets of three images. A computer manipulates the images to get rid of the grid lines and create a 3-D view of the tooth.

“It's infinitely faster [than an x-ray],” says Girkin. The entire process is in real time and takes about 20 seconds. It is even faster if the dentist wants to take thicker, less in-depth images.

Girkin hopes the device will be further developed to have the capacity to give data regarding how much mineral is lost in the tooth and its depth. “Now we are looking to start working with somebody to take this through to a commercial device,” he says. Girkin anticipates developing a low-cost instrument that will gain an early acceptance from dentists, but is aiming for the European market first.

“Getting medical devices approved in the United States is a nontrivial process,” says Girkin. “The idea is to get this worked up and turned into a product within a European context, and then expand it, once we have reliable data, to America.”

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