VOA常速英语:Technology Reduces Time in Dentist’s Chair

WASHINGTON— Medical robots help surgeons perform delicate operations more safely and with greater dexterity than with instruments manipulated by hand. Such sophisticated tools also help doctors work more quickly. One machine reduces the time it takes to manufacture dental crowns to just a couple of hours.

Computer-aided medical instruments are increasingly making life easier for doctors and their patients.

It used to be that the common but complicated procedure to get a tooth crown required several visits to the dentist’s office. While a dental technician was preparing the permanent replacement for a damaged tooth, the patient had to wear a temporary crown.

Since the mid-1980s, this procedure has gradually been taken over by robotic machines that reduce the job to just over two hours. Sitting in the dentist’s chair takes even less time.

“It’s about 12 minutes worth of chair time for the patient and the rest of the time it’s work that’s taking place outside the patient’s mouth,” said dentist Michael Silveus.

At his office in Northern Virginia, close to Washington, Silveus and his assistant prepare a patient’s tooth for a new crown.

The actual drilling takes about five minutes.

Instead of making the impression of the damaged tooth in a plastic material, Silveus uses a wand with a video camera to scan the tooth and the surrounding area.

At this point the computer takes over, designing the new crown and creating instructions for a robotic milling machine.

A porcelain cube, no larger than the tooth, is inserted between two precise drills, similar to the dentist’s drill, that grind away excess material, turning the cube into a perfectly matching tooth crown.

To harden, the crown must be baked at high temperature for about ten minutes. During that process, it also gets tinted to match the color of the neighboring teeth, so it is ready to be cemented in the patient’s mouth.

Patients are pleased with the result.

“It feels amazing. The tooth feels like my tooth,” said one patient.

Silveus said even this technology may someday become obsolete.

“The other thing we look forward to is genetic engineering and eventually cloning, so you can make the crown out of actually enamel, just like the patient’s natural teeth are,” said Silveus.

But for now, he said, his patients are happy to be able to get a new crown in just one visit.