Detecting Decay

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The CarieScan, which is about the size of an electric toothbrush, works by sending an alternating current of electricity through a tooth at up to 10 different frequencies. By changing the frequency of the signal, researchers are able to examine different depths under the enamel and create a spectrum of impedance points--the higher the impedance, the more sound the tooth. Software built into the device plots and analyzes the spectrum against a predefined map. The map was created from sample tests of both sound and damaged teeth.

The results are displayed to the dentist within seconds, in two different ways. A color-coded display in the shape of a pyramid ranges from green to red, like a traffic light. Green indicates that the tooth is sound and free of any damage; yellow is an intermediate range that means the tooth has some form of damage; and red indicates tooth decay. If the color yellow appears, a screen will display a numerical score from one to ninety-nine; the closer that score is to ninety-nine, the worse the damage.

Before using a CarieScan, a dentist must make sure that her patient's teeth are dry enough that electricity does not flow around a tooth and into the gums, but not so dry that electricity does not flow at all. In either of those instances, no harm is done to the patient, but the device will short-circuit, and no reading will be displayed.

This is a simple, painless test to detect tooth decay early and give dentists the opportunity to reverse decay or arrest it without having to fill a cavity, says Hall.

Niederman says that the CarieScan is promising, unique, and useful, but he wants more evidence that it can spot significantly more cavities than a dentist can visually, and that such detection would change what is done therapeutically. IDMoS is working on a sensor to get in between teeth, into areas that are hard for dentists to see and where x-rays cannot be used. "If they can do that, they are an absolute winner," says Hall.

The CarieScan was launched last month in the United Kingdom and Ireland, and it retails for approximately $3,000.