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Dentists may want to handle their red-headed patients gingerly when they climb into the chair.

A recent U.S. study found that natural redheads were twice as likely to avoid the dentist as their blond and brunette counterparts because of fear-related anxiety.

The research — published in a July edition of the Journal of the American Dental Association — attributes the increased sensitivity to a variation of the melanocortin-1 receptor (MC1R) gene, which causes red hair.

It also notes that redheads are resistant to local anesthesia, which could lead to increased anxiety sensitivity, or the "fear of fear." Previous research has suggested they may require 20 per cent more of anesthetics for the drugs to be effective.

Redhead Angela-Jo Griffin says a bad experience under the drill just over a decade ago has left her afraid of dental procedures.

"(The dentist) started pulling out a filling and I felt excruciating pain and realized it wasn't fully frozen," said Griffin. "I jumped out of the chair and I ran down the hall. I didn't want to get it replaced.

"Ever since then, I've been horrified at the idea of going and getting another filling replaced or anything that requires anesthetic at the dentist."

The 35-year-old from Saint John, N.B., cancelled an appointment last week because she didn't want to "risk the pain."

"I'm not afraid as they're starting the procedure," Griffin said. "It's when they actually start to do the work, if I can feel anything at all, that's when the anxiety sets in. I feel myself break out in a cold sweat and immediately I get a hot flash. I usually request a wet washcloth be placed on my forehead, just in case of a possible faint."

An estimated 11 to 20 per cent of people experience "extreme" dental-care anxiety, the study said; an additional 45 per cent report "moderate" degrees of dental fear.

And if dentists want to ensure their patients come through the door for checkups twice a year, the study suggests screening for dental anxiety.

"Dentists should evaluate all patients, but especially those with natural red hair, for dental care-related anxiety and anxiety sensitivity and use appropriate modalities to manage the patient's anxiety," the study said.

A total of 144 people — 67 redheads and 77 dark-haired people — took part in the study, completed at the University of Louisville in Kentucky. Eighty-five participants had MC1R gene mutations: 65 redheads and 20 others.

While 36 per cent of participants admitted to avoiding dental visits, redheads were nearly twice as likely — 46 per cent — to shy away from the chair than their dark-haired peers — 27 per cent.

Although Dr. Don Friedlander, an Ottawa-based dentist of 30 years and current president of the Canadian Dental Association, said he's never noticed his red-haired patients having more anxiety, he said the study highlights the importance of the doctor-patient relationship.

"Dentists are well trained and well-placed to discuss with their patients what their needs are and to manage possible anxiety," said Friedlander, suggesting relaxation techniques ranging from acupuncture and hypnosis, to headphones and simply talking through the procedure in advance.

"Then you make sure that any oral health care is delivered in a way that reduces that anxiety, whether they are red-haired or not."