Finger Lakes Community Health, May 2008
How much is too much? Though over-the-counter products flood the market, nobody seems to know yet.
Any drugstore or supermarket dental care aisle offers plenty of tooth whitening strips, kits and gels alongside the toothpaste, floss and mouthwash fundamentals for a daily oral health regimen.
But unlike these other dental health products, tooth whitening caries a great deal of uncertainty when users stray from the directions or whiten more frequently than recommended.
That’s why Dr. Kimberly Harms, a consumer advisor to the American Dental Association and a practicing dentist in Farmington, Minn., urges patients to consult with a dentist before using any sort of whitening product.
“We know the tooth enamel can stand bleaching for people who follow the directions,” Harms said. “We don’t know what happens to the tooth enamel when you put too much bleach on it.”
Tooth whitening or bleaching techniques have become extremely popular since their introduction in the late 1980s. Patients can choose between professionally applied whiteners and an array of over-the counter whitening products infiltrating store shelves.
Dr. Hans Malmstrom, chair of the Division of General Dentistry at the University of Rochester Medical Center, said the use of tooth whitening products over the past 10 years has been astronomical and shows no sign of abating.
“What we considered white teeth 10 or 15 years ago is now considered to be very dark teeth,” he said.
While clinical studies have proven strips, gels and other whiteners are both safe and effective; most of these studies are funded by product manufacturers.Packaging labels estimate how long a product’s whitening abilities last, but researchers have virtually no information on what happens when overzealous patients misuse or overuse these whitening methods.
“You are venturing into unknown territory if you don’t follow the directions and you do it at your own risk,” Harms says.
Malmstrom said when it comes to over-the-counter products, toothpaste whiteners don’t have much of an effect and it can take years to see a noticeable color difference. There is more support, however, for the effectiveness of over-the-counter strips.
Nowadays, he thinks more people are trying the over-the-counter products but a significant number still head to the dentist’s office for whitening because they often are not satisfied with the results of products available from the drug store.
According to Malmstrom, whitening does cause a microlevel change in the tooth enamel, but the enamel returns to normal in several weeks. There is no evidence that whitening in recommended amounts causes long-term damage to the enamel, he said.But that may not be the case for those who obsess over white teeth and use whitening products continuously.
“We don’t know obviously what happens in long term cases,” Malmstrom said. “I would not recommend that people do it all the time.”
Every tooth has a nerve at its core, and too much bleach can cause hypersensitivity in that nerve. However mild, temporary sensitivity of the teeth and gums is a common side effect to whitening, both at the dentist’s office and at home.
Like Harms, Malmstrom strongly advises patients to see a dentist before using any whitening products. The dentist will check for cavities or leaking filings, which can increase a patient’s tooth sensitivity during bleaching. Nerve damage is also a risk if there is an open cavity, he said.
Those with sensitive teeth or exposed roots due to gum disease may be discouraged from bleaching because of the risk of greater sensitivity. The whitening process won’t aggravate gum disease, but those patients have a greater chance of pain during bleaching.
Those with cavities will also want them filled first so they’re not prone to sensitivity.
Malmstrom said he also makes it clear to patients who already have filling that they may need to be replaced to match their post-whitened teeth.
“The problem is you can’t predict what shade you will have exactly after the bleaching because everyone responds a little bit differently,” he said. “The shade can be a pretty significant difference.”
Teenagers interested in tooth whitening should consult their dentist to make sure their teeth are ready. In Harms’ office, the rule of thumb is high school students are old enough for whitening procedures around the time they sit for their senior portraits.
There are two methods for dentist-assisted whitening. With the first, trays are fabricated so patients can apply the bleaching agent themselves at home over a period of weeks.
The other option is in-office bleaching, in which a significantly stronger concentration of bleaching agent is used two or three times during the one-time visit. Both can reach the same effect, but the one-time office visit offers greater convenience, although Malmstrom said such patients are still usually sent home with bleaching trays to maximize their result.
“Home whitening with the trays is a very good way of doing it because there is a slower conversion and less sensitivity,” Malmstrom said.
Although whitening products have become wildly popular, it’s not yet clear how much whitening is too much. Some people’s teeth are generally more sensitive, while factors such as age, fillings or cavities also can heighten sensitivity.
Harms says the only one-size-fits-all rule of tooth whitening is “if your teeth are hurting, stop.”
This lack of formal guidelines is precisely why Harms wants to know if her patient is contemplating purchasing that box of Crest whitening strips.
“I think sometimes people don’t want to tell their dentist when they are buying something over the counter,” she said. “We see it every day; just talk to your dentist and make sure you get that advice on a personal level.”
As for whether patients should use store-bought whitening products or seek treatment at a dentist office, Harms recommends patients consult their dentist. Over the counter whitening products contain lower levels of peroxide. In–office whitening procedures are administered by a professional, netting results faster but at a much higher cost.
In the Rochester area, Malmstrom estimates the at-home bleaching trays run about $100 to $300 per arch, while the office procedure can run $400 to $800.
As Harms explains it, “You tend to see the cost go up for the convenience of the delivery system.”
The increased interest in tooth whitening and other cosmetic procedures has added a new dimension to the typical dentist’s office. The profession has made great strides in preventing cavities, decay and other tooth diseases, so many dentists have more time to devote to cosmetic procedures.
While going to the dentist has always held long-term cosmetic benefits, Harms enjoys seeing patients get immediate gratification in the form of a whiter smile.
“They like us more now that we are making them look better,” Harms said of her patients. “Adding the cosmetic part of dentistry and combining it with the restorative part has made it a lot more fun.”
Susan Clark Porter contributed to this report.
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