No More Numb Lips : Dentists Testing Electrode Pain Blocker

The patient wasn’t given any drug, but he showed no sign of discomfort as his dentist cleaned out a large cavity and filled the tooth.

With a mere twist of a knob on a little black box, Richard Kindy controlled the output of an electrical device that stimulated his nerves and blocked his perception of pain. The makers of the device expect that it will replace injections of drugs to block pain in many dental patients, once it gains federal approval.

All Kindy felt as Dr. Dennis Hogan worked was pressure and a tingling sensation underneath his right eye, where an electrode was attached to his facial skin.

“I wouldn’t have known whether he was working in and around a nerve or not. I didn’t feel a thing,” said Kindy, 58, of St. Louis Park, Minn. “I was not aware of pain.”

Hogan has used transcutaneous electrical nerve stimulation, or TENS, on about 200 patients over the last two years, as part of preliminary tests.

“At this time, we’re using it mainly for fillings, some crown preparations and in the treatment of periodontal disease,” he said. “Most of these situations usually require the injection of Novocain.”

Hogan said that about 130 million dental procedures each year in the United States involve injection of a pain-blocking drug.

“This would not replace all of those,” he said. “At this point, we’re not recommending that it be used for extractions.”

Hogan said that there is no lingering effect, such as numbness, and that his TENS patients are able to go from the dentist’s chair to a speaker’s platform or to drink a cup of coffee without having it dribble from numbed lips.

The system combines the technology of Medical Devices Inc. of St. Paul, which produces the electrical stimulator, and LecTec Corp. of suburban Minnetonka, maker of a synthetic tape that adheres to the skin and transmits electrical impulses to the facial nerves.

Bruce MacFarlane, a scientist and director of clinical services for Medical Devices, said the use of electrical stimulation in dentistry is an adaptation of the TENS system widely used to block chronic pain and to make patients more comfortable after surgery.

“It’s stimulating nerves. How that interferes with the perception of pain simply is not known,” MacFarlane said. “What we do know is that in chronic pain, especially in acute pain, it is clinically effective.”

“There’s never been any evidence . . . of it hurting nerves,” he said. “It’s battery operated, limited output.”

The Assn. for Advancement of Medical Instrumentation sets standards for maximum output of electrical stimulation, he said. “Ours is only 20% of their recommended maximum, and that maximum has a safety factor built in.”

Controlled scientific testing of the system was scheduled for Oct. 1 at the University of Minnesota Dental School. MacFarlane said national marketing is expected to begin March 1.

Hogan doesn’t offer the stimulation option to all of his patients, only to those with a low level of fear and a high degree of trust.

Kindy was an ideal patient. He said dental work has never made him nervous and he doesn’t feel apprehensive when he hears the drill.

“This is the first time I’ve ever had it done and there’s no question that I will use it again,” Kindy said of the electrical nerve stimulation.

“Many times I’ve gone without Novocain just because I hate that darned shot. I’ll never go back to Novocain, not when this works.”