The scourge of yellow and stained teeth used be looked upon as almost a right of passage—once you became an adult, it was generally assumed your teeth would reflect the wear and tear of coffee, tea, wine, smoking, or just plain living. But less-than-pearly whites are now considered cosmetically damaging, something to be scrubbed, bleached, or zapped away. Almost all of them claim to be safe, but are they really? I’ve seen what happens when you bleach a T-shirt—it usually makes the fabric thin and weak—so what happens to our precious teeth when we bleach them back to our cream-colored past?
Fighting Tooth and Nail
Teeth whiteners work in two general ways, either through surface polishing or through bleaching the tooth and this makes all the difference in their effectiveness and side effects.
Most over-the-counter whitening toothpastes are non-bleaching, meaning they physically or chemically remove surface stains but leave the natural color of your teeth intact. They are often referred to as dentifrices and contain abrasives that polish the tooth or non-bleach chemicals, like sodium tripolyphosphate, that help remove stains. In general, whitening toothpastes can lighten the color of teeth slightly, but won’t be able to make them an entirely different color.
The other way to whiten teeth is through bleaching products, which contain peroxides that can change the intrinsic color of the tooth in addition to removing surface stains. Many people know that brushing with a diluted solution of hydrogen peroxide can help lighten teeth and this is essentially the same mechanism working in bleaching products. Over-the-counter home-based gels and solutions contain around 10 percent carbamide peroxide, which breaks down into hydrogen peroxide and then bleaches the teeth.
Professionally applied teeth whiteners work in the same way, but their peroxide concentrations are higher, ranging from 15 to 35 percent. Sometimes they’re used in combination with a laser. While at-home methods usually involve strips that you’re supposed to apply for an hour or so over the course of a few weeks, professional treatment takes an hour or so.
Safe or Silly?
Whitening toothpastes are generally considered safe, though people with gum or tooth erosion might want to consult a dentist before using. Teeth bleachers, on the other hand, do come with risks.
According to the American Dental Association, the known and most frequent side effects of bleaching treatments are tooth sensitivity and irritation to the gums, but both of these are usually temporary. Perhaps the most concerning, yet not fully researched side effect, is the potential for enamel loss. A study published in the March 2009 issue of the Journal of Dentistry indicates that at-home and professional tooth bleaching products cause enamel loss on a very small scale. Shereen Azer, an assistant professor of restorative and prosthetic dentistry at Ohio State University, and colleagues looked at the effect of name-brand home strip whiteners and professional trays on samples of human teeth. Following the
While other studies have looked at how these whiteners affect tooth enamel hardness, many results were inconclusive. This study was the first to measure enamel hardness at the nanoscale level, which is one billionth of a meter. They found that the treated teeth lost an average of 1.2 to 2 nanometers of enamel—imperceptible to the human eye, but potentially of concern for use over the long-term. Tray methods of treatment reduced enamel hardness more than the strip treatments. Though enamel is the hardest structure in the body, it can erode. Teeth whitening products with bleach may erode this enamel, though experts do think fluoride is able to promote enamel re-mineralization.
With Dentist or Without?
Although more research needs to determine what, if any, long-term risks are associated with this enamel erosion, other potential risks are involved. The ADA notes that on rare occasions “irreversible tooth damage has been reported” when using professional grade bleaching agents.
Another recent concern is the rise is in the kiosk-style bleaching services available at malls and stores. These spots aren’t regulated and they often use concentrations of bleaching products usually reserved for dentist chairs. The ADA recommends getting a checkup before bleaching in order to identify potential problems like gum disease, cavities, cracked teeth, or root problems. They also note that whiteners only work on natural tooth enamel, not on crowns, veneers, or tooth-colored fillings.
So is it safe to bleach your teeth? It seems relatively so, though the long-term effects haven’t been fully studied. And one thing is clear—it’s not permanent, so if you enjoy a cup of joe or a glass of Pinot, you may be facing a future full of regular bleaching appointments.