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Canadians spend millions of dollars annually on tooth-whitening products. But do they work?
Whiter teeth as a biblical imperative? That might be going a bit far, but Toronto-based esthetic dentist Dr. Edward Philips points out humans have seen white teeth as a sign of power and prosperity since at least the time of the Old Testament. In the book of Genesis, for example, the patriarch Jacob blesses his son Judah, noting the beauty of his eyes, "darker than wine," and his teeth, which are "whiter than milk?’
More recently, a slew of products and procedures designed to make teeth white as milk has crowded drugstore shelves and made its way into dentists’ offices. From over-the-counter pastes, gels and strips to dentist-prescribed bleaching kits, lasers and custom-fitted mouth guards, tooth whiteners have taken the market by storm.
According to the American Academy of Cosmetic Dentistry, the number of tooth-whitening procedures has grown by more than 300% since 1996 and sales are expected to more than double to US $400- million in 2004 from US$187-million in 2002. Exact figures are not available for Canada, but the growth is comparable.
Just ask Rob Gray, 33, a writer and program head at the Vancouver Film School. Most of his friends have tried various whitening methods, he says, even making pilgrimages across the U.S. border to buy Crest WhiteStrips before they were available in Canada. He decided to give whitening a whirl after seeing a photograph of himself in which his teeth looked yellow.
"That made me feel self-conscious. I tend to smile widely, and I think I’d always kind of gotten away with murder with my smile. But now my eyes were much whiter than my teeth. I wanted to brighten it up?"
For an hour a day for two weeks, Mr. Gray used the thin, transparent strips, which cost about $45 and are coated with a layer of gel containing peroxide – the same stuff used to bleach hair. The strips adhere to the upper and lower teeth, forming a seal and allowing the peroxide to penetrate the outer enamel to the dentin, which discolours over time as we age. Coffee, tea, red wine and cigarettes – all of which can stain the enamel – also contribute to external tooth discolouration.
Mr. Gray’s teeth did brighten up. Six months and two-plus lattes a day later, however, the yellow has returned and he is contemplating repeating the process – despite the burning sensation in his gums and the tooth sensitivity he experienced during the first few days.
For those considering over-the-counter whiteners, Dr. Philips says strips make more sense than brush-on peroxide gels or kits that offer whitening gel in mass-produced mouthguards or trays that fit around teeth. Researchers at the University of Florida College of Dentistry for example, found the strips are five times as effective as gel, which stays on teeth only a few minutes before saliva washes it away. With generic trays, the gel can also leak out or become contaminated by the surrounding air and saliva.
Dr. Philips also points out so-called "whitening" toothpastes are, in fact, stain removers. While they may be effective at removing those coffee, wine and nicotine stains on the outside enamel, they will not actually change the colour of yellowed teeth. Dr. Philips says strips and other OTC whiteners will take longer to work than dentist-prescribed and supervised whitening, which uses custom-fitted dental trays to hold the peroxide gel – in potentially stronger concentrations – in place against the teeth. Because the guards conform exactly to the teeth, there is less chance of the solution being contaminated or diluted by saliva and air. A well-fitting tray will also help prevent the gel from leaking and from touching the gums, thus helping to prevent gum irritation. Patients wear the trays overnight or for several hours a day, for four or five days to up to two weeks, depending on the strength of the peroxide, their comfort level and their dentist’s recommendations. At-home whitening under a dentist’s supervision can
In-office whitening procedures can take less time, as dentists use lasers (usually on only one or two problem teeth) or bright light, both of which are thought to activate the peroxide and make it work faster. In an office setting a dentist can use higher concentrations of peroxide and monitor the patient, who may also wear gel in mouth-guards for a few nights afterward, just to shore up the effects. Dr. Philips usually recommends patients follow up with one night of whitening every 12 months in order to keep teeth pearly white.
As millions of cases of tooth-whitening in North America suggest, people seem more than comfortable with the idea of putting peroxide in their mouths. Still, some are more cautious. Dr. Laura Tam, an associate professor in the department of restorative dentistry at the University of Toronto’s faculty of dentistry, points out up to two-thirds of whitening patients experience some degree of tooth sensitivity.
"It has been documented as transient and should not persist, but does represent some type of inflammation of the pulp," which is the innermost part of the tooth, where the nerve lies. Peroxide bleaches can also blanch the gums and irritate the mouth’s soft tissues. As for long-term negative effects of bleaching on tooth structure, and peroxide on the human body, Dr. Tam cannot comment because no studies have been conducted.
While hydrogen peroxide has been "adversely associated with carcinogenesis," she noted in a scholarly article on the safety of home bleaching, it is also a substance that the body produces naturally. The bottom line? We need more studies, Dr. Tam says.
In the meantime, she says, clinical studies using a 10% carbamide peroxide gel over two weeks have demonstrated it is safe and effective when used according to directions. Dr. Tam recommends bleaching only with the supervision of a dentist, who can diagnose the source of discolouration and help ensure the method used is appropriate. Children, pregnant or lactating women and anyone with oral tissue problems should avoid whiteners. As for repeated use of bleaching products, she is not comfortable with the practice, although she admits no clinical evidence supports her claim.
Lucas Murnaghan has a pair of custom-made mouthguards sitting in "a neglected drawer" in his bathroom. The 27-year-old surgical resident at the University of British Columbia medical school spent about $250 for a dentist-supervised, at-home whitening kit. He also gave up his daily dose of coffee – switching to caffeine pills to get by. After a few nights of wearing the mouthguards, however, Dr. Murnaghan’s gums begin to hurt and reacted painfully to heat or cold. He gave up on the program – and started drinking coffee again.
"I thought, ‘I’m putting some chemical in my mouth that makes my gums hurt. Maybe that isn’t so good for me. Maybe my teeth are supposed to be this colour and that’s life and I shouldn’t mess with it’."
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