Lasers are latest tool in dentists' hands

THE NEW DRILL

July 23, 1991|By Gerri Kobren

The room looks odd, almost empty except for the dental chair and a white, four-wheeled case the size of a small radiator, with a pencil-thin cable looped at one end.

No sign anywhere of that big mechanism you expect to see in every dentist's office, the mastodon-like hulk that holds the spigot and bowl, the tray full of sharp instruments, the drill that'll soon be jackhammering in your mouth.

Larry Zarzecki reclines in the chair, looking more laid back than any dental patient has a right to be. He doesn't mind going to the dentist, he says. It's the after-effects of the anesthetic he finds most bothersome. "I just don't like to be unable to feel my lip," he explains.

That's why he's come to the Parkville office of Dr. Mark Seward, whose new dental laser, installed last spring, offers the promise of no-pain dentistry. That means no needle, no numbness, no embarrassment when your mouth won't work right for a few hours afterward.

And in some cases, no more expense for the patient than conventional drilling. This particular laser, the only one of its type in the metro area and one of just a handful in the state, sells for $50,000. According to reports from around the country, some dentists are charging more when they use it. But Dr. Seward says he is making it up in volume instead.

"Patients tell their friends about it," he says. "They've become missionaries."

No newcomer to medicine, the laser is already in widespread use in such specialties as ophthalmology, gynecology, dermatology and plastic surgery. More recently, the device has entered orthopedics as well.

Different types have different strengths and weaknesses, making them more or less appropriate for various uses. Overall, however, their effects are dazzling. They can be aimed and applied with such precision that they vaporize tissue a few cell layers at a time. They sterilize what they touch, and cauterize as they cut, so there's no bleeding, little or no swelling and faster healing.

In dental surgery, the advantages are similar: They permit removal of infected or abnormal soft tissue in the mouth -- diseased gums, for instance, or even tumors -- without a scalpel. Dr. Seward uses his laser to zap away tooth decay as well.

He wears special glasses as he works; so does his assistant Theresa Guidici. Patients are protected in wraparound green goggles, since the invisible beam can damage the eyes. Another kind of laser energy produces a red glow at the end of the wire, to show him where he's aiming the power beam.

"I am constantly interviewing patients to get a feel for what they are experiencing," he says. And what they say they feel is a little heat, but no pain, he reports.

Why that's the case is unclear: One theory holds that the energy, moving at many pulses-per-second, demolishes tissue so quickly the nervous system doesn't have time to recognize pain. But Dr. Seward also suggests that the laser might be sealing off the structures that communicate between the outer layers of the tooth and the pulp, which contains the nerve.

Dr. Seward's laser, developed specifically for dentistry, derives its power from a substance called Nd:Yag -- for neodymium:yttrium-aluminum-garnet. Developed specifically for dentistry by a Michigan dentist and his ophthalmologist brother, it received marketing approval from the Food and Drug Administration in May 1990, and has since been sold to nearly 400 dentists nationwide.

But it is not the only kind of laser used in dentistry. Dr. Robert M. Pick, a Chicago periodontist and associate clinical professor at the Northwestern University dental school, has been working with lasers since 1982. His preference is the carbon dioxide type, at least one of which is being used by a dentist in Cumberland.

"The primary use is for soft tissue," Dr. Pick said, listing such procedures as treatment of canker sores and lesions under dentures, removal of malignancies and infected gum tissue, and reshaping of gums. "It's a wonderful, wonderful surgical tool!" he said.

Using lasers on hard tissue -- teeth, that is -- puts Dr. Seward on something of a cutting edge as well. FDA's approval of the Nd:YAG dental laser limits its manufacturer to sales pitches that describe soft-tissue applications.

That doesn't mean other uses are disapproved, according to agency spokesperson Susan Cruzan: The manufacturer simply hasn't presented enough data for FDA to rule on. Cautions from FDA focus on such safety concerns as eye-protection and avoiding contact with flammable substances.

The American Dental Association has reserved judgment, pending more information.

And, in any case, dentists who have lasers are allowed to use them however they please. Dr. Seward has a list of applications: cleaning out the grooves in children's teeth before applying decay-preventing sealants; vaporizing decay; pain relief while he's doing non-laser procedures; reduction of the kind of discomfort that sends so many of us to the drugstore for special de-sensitizing toothpastes.

He used it on his receptionist, Susan Personette, to zap a food-trapping pocket of tissue left from a wisdom tooth extraction; for Ms. Guidici, his office assistant, he lased away some of the excess gum that she thought was spoiling her smile.

The laser can't do everything, certainly. It won't penetrate the hard white outer layer of a tooth, for example, which means "if you need to get through the enamel, you need the drill," Dr. Seward says. He does, in fact, have a drill on a pull-out stand that can be tucked away under a cabinet behind the chair.

But the decay in Mr. Zarzecki's tooth is where the laser can get right to it. Dr. Seward has told the patient to raise his hand if anything hurts. Apparently, nothing does: His fingers, laced loosely over his belt, never even twitch, his breathing remains even.

"That was great," Mr. Zarzecki says. "It's the best thing that's happened in dentistry since the high-speed drill. I could have fallen asleep."

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