Detecting Decay

A new device could help dentists better detect the early signs of tooth decay.

Eating too many sweets this holiday season could cause small lesions to develop in your teeth. If undetected by your dentist, these early signs of decay could turn into painful cavities. Now researchers at IDMoS say that they have made a device that uses electrical impedance to identify tooth decay earlier and more accurately than current methods do.

Protecting your sweet tooth: The CarieScan is a new device developed by IDMoS that uses electrical impedance to detect the early stages of tooth decay. The device is about the size of an electric toothbrush. It measures the tooth’s response to alternating currents of energy. The results are analyzed by an onboard computer and displayed onscreen in two different ways: a color-coded display and a numerical reading. The device retails for approximately $3,000 (top). Dentists who want to collect and review patient data can use a device that wirelessly connects to the instrument (bottom). Together, both items cost $4,000. Credit: IDMoS

The device, called a CarieScan, sends a small alternating current of energy through a tooth. A sensor on the tip of the instrument measures the tooth's response to different frequencies, and the results are analyzed by an onboard computer. A color-coded display and a numerical reading alert the dentist of the health of the tooth.

"The technology is leading edge, and the device appears to be the best so far for automated [decay] detection," says Rick Niederman, the director of the Center for Evidence-Based Dentistry, at the Forsyth Institute, an independent science and health research facility in Boston.

Laser-based techniques are one of the newer methods for detecting tooth decay. Instead of sending out an electrical current, they focus pulses of laser light on the tooth. One type of laser device that has become popular in dentists' offices is called a Diagnadent. The device is based on light-induced fluorescence. Light beamed on the tooth is absorbed by chemicals from the decay-causing bacteria that have seeped into areas of mineral loss, and then it's rereleased at a lower energy. The Diagnadent measures the change in wavelength; a higher reading means more decay.

Another technique, being developed at Quantum Dental Technologies, a startup based in Toronto, Canada, uses light waves and thermal radiation. (See "Quantum Detection of Tooth Decay.")

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The problem with laser devices is that they have a high number of false positives because they identify teeth with stains--whether from coffee, tea, or naturally occurring tartar--as decay, says Andrew Hall, an associate professor at the Dundee Dental Hospital and School at the University of Dundee, in the United Kingdom. "And the use of heat may mean that small intra-oral variations in temperature, such as those caused by breathing, could have a profound effect on results," says Hall.

The device made by IDMoS has the same sensitivity as a laser, but instead of having a 30 to 40 percent false-positive rate in detecting decay, the rate is only 10 percent, says Alasdair Christie, head of development and operations at IDMoS. "Electrical resistance is a direct method of measuring the structure of a tooth because the mineral that is lost in the very early stages of tooth decay is replaced by a liquid, such as saliva in the oral cavity, and that reduces the resistance of the tooth to electricity," he says.