Crowning Achievement

By THOMAS K. GROSE Wednesday, Oct. 30, 2002

Illustartion for TIME by IAN EVANS

Wednesday, Oct. 30, 2002

Dental patients facing the prospect of having a crown fitted probably don't anticipate the experience with wholehearted enthusiasm. But their anguish levels might skyrocket if they knew what could happen if the implant—the artificial root that's put into the bone—is drilled into the wrong area. In the lower jaw, if it hits a nerve, a person's lower lip can become permanently numbed. In the upper jaw, there's the risk of the dentist drilling into the sinus cavity, damaging it. To the rescue comes med3D, a young German company using new software technology developed at the University of Heidelberg that enables dentists to fit prosthetics with greater precision. "There is a lot of guess work involved" in fitting crowns, and this system eliminates it, says Wolfram Stein, med3D founder.

Here's how it works. A wax mockup of the implant is coated with barium sulphate and placed into a patient's mouth before a computertomographic (CT) scan is done. (The coating allows the wax model to show up on the scan.) A radiologist transfers the image onto a CD-ROM, which the dentist slides into a PC. Med3D's software lets the dentist move the virtual implant around on the screen, finding its ideal placement and ensuring that danger zones, like nerve clusters, are avoided, and also ensuring that there is sufficient bone available to hold an implant. The virtual implant can be seen in either 2-dimensional or 3-dimensional images. "It's pretty much like a video game," Stein explains.

The software calculates the exact measurements of the final fit, including the depth of the drill holes. This is fed into a positioning device that Stein likens to a flight simulator. That device—developed by med3D and German company, Georg Schick Dental, and manufactured by Schick—then punches out a template with an exact drilling plan. The dentist then works from the template while fitting the implant, and can concentrate on the procedure without having to look up at a screen.

Stein is an electrical engineer who developed the technology while working on his doctorate in bioengineering at the robotics lab of Heidelberg's Department of Craniomaxillo Facial Surgery. He started his company, located at the Heidelberg Technologiepark, two years ago, after receiving some federal government seed money, as well as venture capital funds.

There are rival technologies around, including one that uses laser rapid prototyping, but Stein says they're more expensive than med3D's. His system sells for about $15,400.

So far, he says, feedback from dentists who have used it is positive. "They're excited by the 3D images." Perhaps more importantly, patients are enthusiastic about it. One British woman, after hearing about the technology, travelled to Germany to have her crown fitted, he says. A patient can sit next to the dentist at the PC and be shown where the implant will go. Notes Stein: "They like having much more predictable results." Given the potential consequences of an improperly fitted crown, that's hardly surprising.