You can blame it on Hollywood or Instagram, but it’s undeniable—everyone wants a bright, white smile. This has led to an explosion of teeth whitening or “bleaching” products, and many of them contain hydrogen peroxide.
“Hydrogen peroxide has actually been used in teeth bleaching products and oral care products like toothpaste and mouthwash for decades,” dentist and Waterpik spokesperson Chris Strandburg, DDS, tells Health.
But how safe is the ingredient really, and—for those who’re on a quest for the perfect Hollywood smile—how effective is it as a teeth whitener?
What is hydrogen peroxide, and how does it make teeth whiter?
Hydrogen peroxide is an acidic chemical compound with the formula H₂O₂, and in its pure form, it’s a very pale blue liquid. Oral care products aside, it’s often used as a household cleaner, bleaching agent, or antiseptic.
Although hydrogen peroxide has only one more oxygen molecule than water (that’s the H₂ part of its chemical formula), it has very different properties. It’s a powerful oxidizer in high concentrations and can be corrosive to the eyes, skin, and respiratory system. For this reason, it needs to be used with caution on people and animals.
It’s hydrogen peroxide’s strong bleaching properties that make it a common ingredient in teeth whitening products. “Hydrogen peroxide brightens and whitens the teeth via a chemical process, by breaking down the stains from polymers into monomers via an oxidation process,” UK dentist Dr Lisa Creaven, co-founder of Spotlight Oral Care, tells Health. “In teeth whitening products, it works to dissolve stains, so teeth are gradually and safely whitened without damaging tooth health.”
But because hydrogen peroxide is a potent bleaching agent, it’s typically diluted with a whitening product, such as baking soda, to prevent damage to the enamel and gums.
How safe is it to put hydrogen peroxide your teeth?
When regulated and controlled, hydrogen peroxide is completely safe, both in toothpaste and other products, like a gel that is squeezed into a rubber tray that wraps around the user’s teeth, or teeth whitening strips. These products allow the hydrogen peroxide to come in close contact with the tooth surface; where it breaks down stains and brightens the overall shade of the tooth. “Hydrogen peroxide has a long track record of safety for bleaching teeth without significantly affecting the strength of tooth enamel,” Dr Strandburg says.
However, it is possible to overdo it and cause damage to your teeth and gums over time. Teeth whitening products containing hydrogen peroxide typically contain concentrations of the compound from 3% to 20%—even higher in the dentist office. Most toothpaste and mouthwashes, for example, contain a lower amount of hydrogen peroxide, which makes the bleaching properties weaker and therefore safer for long-term use. In these situations, hydrogen peroxide has another role to play—helping to kill the bad bacteria that contributes to gum disease, which results in improved gum health.
Teeth bleaching strips or gels, however, contain hydrogen peroxide in higher amounts, and so should be used less frequently. “Prolonged bleaching with these high concentrations of hydrogen peroxide, especially when used multiple days in a row, can lead to highly irritating gums and sensitive teeth,” Dr Strandburg warns. “Gum irritation can get severe if more bleaching is done when the gums are already irritated. Tooth sensitivity is usually temporary (24 hours or so), but significant bleaching can increase tooth sensitivity permanently with long term use.”
Dr Strandburg recommends limiting an initial treatment to seven to 14 sessions. An even safer approach is to give your teeth and gums a day’s rest in between sessions. If you have more than 20 bleaching sessions per year, you risk affecting the integrity of your teeth’s enamel, due to the slightly acidic properties of high concentrations of hydrogen peroxide. If you follow this advice, Dr Strandburg says most people “get a nice boost to their tooth brightness with little to no lasting negative effects.”
Orthodontist Heather Kunen, DDS, MS, co-founder of Beam Street, advises against using any whitening product course with hydrogen peroxide more than once or twice per year. “Once you have achieved the level of whitening you want (over the course of three to 10 days), wait at least another six to 12 months before whitening again,” she tells Health.
You can buy hydrogen peroxide solutions over the counter at your pharmacy and online, but great care should be taken if you create your own teeth whitening mixture at home. “The bleaching agent can badly burn your gums and damage enamel if the concentration is too strong,” Dr Kunen warns. She recommends at least a 1:1 ratio of water to hydrogen peroxide if you are creating your own solution but always check with your dentist first.
Are there teeth-whitening alternatives to hydrogen peroxide?
Hydrogen peroxide isn’t the only teeth whitening ingredient out there. Although baking soda isn’t a true bleaching agent, Dr Kunen says it helps to lift stains from teeth to give them a nice sparkle. Pthalimidoperoxycaproic acid (PAP) is another bleaching alternative. “Other whitening brands are starting to stray from traditional peroxides and use new formulas that are less harsh, such as pthalimidoperoxycaproic acid (PAP),” she adds. “PAP is far less harsh on the enamel and gum tissues than hydrogen peroxide so that this formula may become more popular for other brands shortly.”
You may have also heard about charcoal for teeth whitening, but Dr Creaven advises against this. “Research shows that toothpaste and teeth whitening products that contain abrasives such as charcoal can cause irreversible damage to the tooth surface,” she says. “charcoal-based toothpaste work by mechanically removing the outermost layer of the enamel surface, which physically and permanently removes tooth structure. When these products are used over a long period of time, they can make the top surface of the teeth rough and dull, leading to a more yellow appearance overall.”
Regardless of how you choose to whiten your teeth, it’s a good move to chat with your dentist and make sure your teeth and gums are in good shape. “Dentists have the health of your mouth as their priority so making them part of your routine will ensure excellent oral health throughout your life,” Dr Creaven says.
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