Pearly whites may have price

Overusing at-home teeth-whiteners may cause harm

August 20, 2006|By CAROLYN POIROT | CAROLYN POIROT,MCCLATCHY-TRIBUNE

Apparently believing that what's worth doing is worth doing to excess, some consumers think there is no limit to how white they can make their teeth.

But if you intend to get the most sparkling, movie-star-white smile possible and ignore your dentist's directions or the labels on the bleaching agents, you could irritate your mouth and make your teeth more sensitive to temperature changes, dentists say.

"With hordes of people doing this, [teeth-whitening] is accepted as a very safe thing. ... Of course, there is always the potential for people ... to go online and obtain as much of the stronger bleaches as they want to get their teeth whiter and whiter," said Dr. Bruce Weiner, a Fort Worth, Texas, dentist. "I always remind my patients, what you really want people to say is, 'My, what a pretty smile you have,' not, 'Oh, you bleached your teeth.'"

Wondering whether you've gone too far with your whitening or not enough? Then, read on:

l What is the safest, most cost-effective method for bleaching teeth?

At-home bleaching that has a 10-percent carbamide peroxide material in a custom-fitted tray is the most effective thing you can do for the least investment, says Van B. Haywood, a professor at the Medical College of Georgia's school of dentistry, who published the first studies on take-home tray bleaching in 1989 and about 100 papers on the subject since then. "It provides the best ultimate result with the longest duration. You just have to be patient," he said.

l How long does teeth-bleaching take?

Bleaching with 3 percent to 10 percent carbamide peroxide or hydrogen peroxide takes one to six weeks of two-hour or overnight sessions for most teeth, Haywood says.

Bleaching out nicotine stains will take one to three months, and to get rid of some stubborn stains, including those caused by tetracycline, an antibiotic widely used in the 1960s and '70s, it will take two months to a year, Haywood says.

Higher concentrations (15 percent to 35 percent hydrogen peroxide) are applied in dental offices and take one to two hours over two to four visits, and are sometimes used with lights to "jump-start" the take-home bleaching process.

l Is it safe to use whitening toothpaste on my bleached teeth?

Yes, that's the best way to remove surface stains and keep newly bleached teeth looking white longer, but it does not work chemically from the inside like peroxide bleaches do. Also, try a whitening rinse after drinking red wine, soy sauce, grape juice, cranberry juice, black coffee and colas, especially if you are unable to brush right away.

l Why are my teeth sensitive after bleaching?

The American Dental Association says tooth sensitivity is common during early stages of bleaching treatment. Tissue irritation in most cases results from an ill-fitting tray rather than the tooth-bleaching agents, the ADA says. Both of these conditions usually are temporary.

Dr. Eric Shapira, spokesman for the Academy of General Dentistry, says over-bleaching can also make tooth enamel more porous, which makes your teeth more sensitive to hot and cold, but especially cold.

l Can swallowing some of the bleach cause cancer or other health risks, especially in children?

No. Hydrogen peroxide is not a caustic bleach. It is actually used as a healing agent to swab the throats of babies born with thrush, a fungal infection, Haywood said. And it is often poured into open wounds to prevent the spread of germs.

"Numerous studies have found that dental bleaching agents have no detrimental effects. They do not cause softer, weaker teeth and do not damage nerves," Haywood says. Still, he does not recommend teeth-whitening for pregnant women.

"There is no reason to undergo any elective medical procedures of any kind while pregnant. The trays will last, and you can wait for later -- I usually recommend at least six months after the birth of a baby, especially if you are breast-feeding," Haywood says.

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