So called early decay detectors like Kavo’s popular DIAGNOdent, Air Technique’s Spectra and the Sopro camera (the newest variation of "laser fluorescence") often help a dental practice financially more that it helps patients.

A study published by the American Dental Association concurs, finding “a large number of false-positive results with these devices, which limits their use as a principal diagnostic tool.” Traditional visual exams and X-rays remain the preferred diagnostic method since they are more than enough to root out cavities, the study found.

“They’re not necessary,” according to American Dental Association spokesman Dr. Matthew Messina. “We can do excellent dental work with traditional X-ray, visual, and hand exams alone.”

But that hasn’t stopped the gadgetry from becoming a staple in many dental offices around the nation.

See the article on Fox News: Ouch, New technology makes dental trips even worse

Dr. James C. Hamilton, now retired from the University of Michigan Dental School, led a five-year study that found early treatment of microcavities using a composite filling failed to conserve more of the tooth than watchful waiting until caries [decayed areas of teeth] were diagnosed.

"We found no benefit at any time for early treatment," Hamilton said in an interview. He worries that expensive equipment pushes some dentists toward more aggressive treatment to get a "return on their investment."

"When you buy this new technology to treat incipient carious lesions, you have increased your overhead. You now have to make this piece of equipment pay for itself," Hamilton said. With the cost of a filling ranging from about $100 to $250, dentists might be "using this to find and treat those lesions when in fact they ought to be just watching them," he said.

See the article on ABC News: Unnecessary Fillings Dentists Drill

"There is a weak correlation between DIAGNOdent readings and carious lesion depth and volume."

See the study from the Journal of Operative Dentistry

Whether to fill based on a DIAGNOdent reading “depends on the risk,” said Dr. Margherita Fontana, an associate professor at the University of Michigan School of Dentistry. An adult with great dental hygiene is probably at lower risk of seeing a microcavity progress than a teenager who drinks soft drinks all day, she said.

But other experts such as Dr. James Bader, a research professor at the University of North Carolina School of Dentistry, are critical of the Diagnodent and other early-detection devices because they identify areas on teeth that aren’t actually carious lesions [decayed areas of teeth].

See The New York Times article: A closer look at teeth may mean more fillings by dentists

Dental Health of Colorado's website promotes the use of DIAGNOdent and has recently added the expensive Sopro camera which uses the same “laser fluorescence” technology.