Virtual-reality patients feel no pain

Dentistry: Sophisticated computer simulators help students learn how to scrape and drill.

October 15, 2001|By Martha Woodall | Martha Woodall,KNIGHT RIDDER/TRIBUNE

PHILADELPHIA - The two new patients in the second-floor lab at Temple University's dental school do not cry out in pain or complain that they can't keep their mouths open any longer.

But if a student drills too far and hits a nerve, a bright-red spot of blood appears: virtual blood.

Meet the DentSims, the latest thing in dental school technology, allowing students to practice dental techniques on sophisticated simulators before ever working on human patients.

While dental students have long gained hands-on experience from unresponsive mannequin heads, a DentSim is a computerized "patient" that provides a much more realistic training experience and also immediately evaluates a student's work.

A DentSim consists of a pneumatically controlled blue mannequin with an articulated jaw.

It has 32 removable teeth. It has pliable cheeks. It even seems to salivate, although the water actually comes from the drill.

The mannequin is at the heart of a sophisticated system that includes dental equipment, two computers, and a precision motion-sensor system that reads signals from a series of light-emitting diodes to produce 3-D images as a student works in the mannequin's mouth.

"It is a good training tool, and it is good for precision and careful work," said June A. Sisson, an assistant professor at Temple's School of Dentistry in Philadelphia, whose third-year students began training on the simulators a few weeks ago. "I think most dental schools will end up with at least a couple of these."

The units cost $75,000 each.

Sisson said the DentSim database included simulated patient records with common dental situations - for example, cavities, which show up as green spots on the images of teeth that the student sees on the computer monitor. The student uses an actual drill to bore into the DentSim's removable teeth.

"Once you have gotten rid of the cavity, you hear a ding," Sisson said. "And if you make a mistake, you hear a different kind of noise."

It's similar to the sound that accompanies a computer error message. The student also can look at a cross-section of the tooth and many other views to find out how well he or she performed.

Drilling too far produces not just the warning sound, but also that small dot of virtual blood on the computer screen.

The University of Pennsylvania's School of Dental Medicine pioneered DentSim usage.

Judith A. Buchanan, a professor at the dental school, said the university began experimenting with one unit in 1998, set up a research team, and spent three years evaluating the effect that DentSim had on learning before including it in the school's curriculum.

"We found it to have a lot of potential," Buchanan said.

Penn's research found that students who worked on a DentSim were able to refine their skills more quickly than students who practiced on traditional mannequins. Students who work on the old-fashioned mannequins must ask a faculty member to take measurements to evaluate their work.

"With the virtual-reality unit, there is immediate feedback, and you can ask for feedback as much as you want without waiting to get the professor's attention," Buchanan said. "And with the visuals, you are able to see your mistakes side by side with the ideal presentation."

On the computer screen, students can see color-coded images of the tooth they just drilled, as well as cross-sections and other 3-D representations.

"This type of feedback is instrumental in helping students understand," Buchanan said.

Penn has four of the DentSim units, she said.

"It is very exciting," said Buchanan, who founded a group called the DentSim Users Consortium for dental schools that are training students on the simulators. "I get calls from all over the world about ours."

Developed and marketed by DenX, an Israeli company, DentSim incorporates optic, imaging and simulation technologies.

Shlomo Lehavi, president and chief executive officer of DenX-America Inc. in Tarzana, Calif., said the company spent nearly seven years and invested $14 million to develop the system. The simulator was introduced in 1998, and DenX began extensive marketing about two years ago in the United States.

About 100 DentSims have been sold to dental schools in the United States. In addition to Temple and Penn, DentSim users include dental schools at Case Western Reserve University in Cleveland, the University of Missouri at Kansas City, and Columbia University in New York.

The largest installation is at the University of Tennessee; the state Legislature provided funds to equip the university's College of Dentistry in Nashville with 40 DentSims.

"The biggest problem in dental school is that you are in the hands of your professor," said Lehavi, who is a dentist.

Students who labor on old-fashioned mannequins show their completed work to their professor, who sees the finished work, but rarely the process.

Lehavi said studies have suggested that dental students waste as much as 90 percent of their lab time waiting for a professor to check their work before the students can proceed to the next step.

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