If you’re after brighter, whiter teeth, you’re in good company. “Every day, at least one patient in my office asks about whitening,” says Kimberly Wright, a dentist at Advance Dental Arts Center in West Linn, Ore.

As we age, the enamel on our teeth naturally thins, which makes them more prone to pesky surface stains (regularly sipping on red wine, coffee, and tea doesn’t help, either).

With so many teeth whitening products on the market, from over-the-counter whitening kits to in-office professional treatments, it can be overwhelming to know which ones are right for you. Here, dentists weigh in on everything you need to know about the best teeth whitening products—plus, smart at-home strategies to help keep your pearly whites, well, white.

Ingredients that whiten teeth

Before you start adding teeth whitening products to your shopping cart, it’s important to know which ingredients actually help you achieve a brighter smile. According to the American Dental Association, there are two main types of whiteners on the market: bleaching products (which contain peroxide) to lift both deep and surface stains, and non-bleaching products to lighten surface stains only.

Bleaching products usually contain either carbamide peroxide or hydrogen peroxide, but carbamide peroxide (also known as urea peroxide) is the most common, says Dr. Wright. “When water contacts this white crystal, the release of hydrogen peroxide lightens the teeth,” she explains.

Should you whiten your teeth?

Although most people will see some improvement in the appearance of their teeth when using a whitening product, others should proceed with caution. “Generally, bleaching is successful in at least 90% of patients,” says Dr. Wright. “But it may not be an option for everyone.”

If your teeth are darkened from age or food (particularly coffee and tea) and have discoloration that appears yellow, brown, or orange, you’re likely a good candidate for teeth bleaching, Dr. Wright says. On the other hand, discoloration that appears gray is typically caused by smoking, use of the antibiotic tetracycline, or fluorosis, which results from consuming too much fluoride while teeth are forming. While bleaching may help lighten these stains, the results will be less dramatic.

Before using any whitening product—even over-the-counter ones—it’s a good idea to ask your dentist if they’re safe for you to use. For example, anyone with gum disease or worn tooth enamel should avoid bleaching products altogether, since they could irritate already-sensitive teeth. People with loose or broken fillings are also at risk: “The bleach can seep deep into the tooth and adversely affect the nerve,” says Dr. Wright.

How often should you whiten your teeth?

There’s no one-size-fits-all answer for how often a person can whiten their teeth. It largely depends on the type of whitening product you choose (more on that later). At-home products such as whitening kits can usually be used daily until you achieve your desired shade, says Dr. Wright. After that, once- or twice-monthly use will help you maintain your results.

However, when thinking about frequency, it’s important to consider the active ingredient of the product you’re using and how strong it is. For example, professional treatments typically contain higher percentages of whitening agents. “The higher the percentage of the active ingredient, the faster it will work, but the potential for more tooth and gum tissue sensitivity also increases,” says Edward Wilson, DDS, a dentist in the New York City area.

When you choose to whiten your teeth can make a difference too. According to Dr. Wright, the best time to whiten is just after you’ve visited your dentist for a cleaning.

“Surface stains have been removed by your hygienist, so the bleach products are working directly on the tooth and not on built-up stains,” she explains.

Over-the-counter whitening kits: What to know

Over-the-counter home kits are one of the most popular ways to whiten your teeth, and for good reason: They’re available everywhere, relatively easy to use, and can give you visible results without having to shell out for an in-office treatment.

“These kits are great,” says Lauren Levi, clinical instructor of dentistry at the Icahn School of Medicine at Mount Sinai. “They adapt to your teeth, aiding in efficiency.”

Most of these kits contain peroxide strips that can be worn daily for about a month. You can expect to brighten your smile by about one shade, and the results usually last six to 12 months. Whitening strip kits can cost anywhere between $20 and $50.

Home whitening kit to try: Crest 3D White No Slip Whitestrips, Professional Effects

To buy: $64; walgreens.com

Crest’s easy-on, easy-off whitening strips are a go-to. This kit includes 30 strips that will give you brighter teeth within one month. One thing to note: If your teeth are somewhat crooked, you may see some white splotches after removing the strips, since they may fit closely on one side and not the other.

Home whitening kit to try: Rembrandt Deeply White 2-Hour Whitening Kit

To buy: $23; amazon.com

This Rembrandt kit contains COMFYTRAY trays that you fill with whitening gel and let sit on your teeth for 20 minutes. There’s enough gel for four uses, so you can have brighter pearly whites after just two hours of wear.

Home whitening kit to try: Crest Whitestrips With Light

To buy: $61; amazon.com

For superfast at-home whitening, you can’t beat this new product from Crest (which was a winner in Health’s 2017 beauty awards). The kit includes a handheld light to help target deep-set stains while the whitening strips work their magic. You’ll see an improvement in one hour of use, and the results last six months.

Over-the-counter whitening toothpastes: What to know

In terms of ease of use, it’s hard to beat whitening toothpaste; you’re already brushing your teeth, so you might as well whiten them at the same time, right?

Whitening toothpastes contain mild abrasives that help remove superficial stains. “Most leading toothpaste companies use the finest silica particles that will mechanically remove stains but not excessively remove enamel, which can never grow back,” says Dr. Wright.

These products are best for lifting newer, fresher discoloration, but you shouldn’t expect them to make your teeth multiple shades lighter—one shade is more typical. This option is also one of the most affordable, as whitening toothpastes usually ring in at about $4 to $10 for a tube.

When shopping for whitening toothpaste, look for one that has a seal of approval from the American Dental Association (ADA) on its packaging. Also important: Make sure it still contains fluoride so you continue to protect teeth from cavities—especially if you’re using it as an everyday substitution for regular toothpaste.

Whitening toothpaste to try: Colgate Total Advanced Fresh + Whitening Gel Toothpaste

To buy: $4; walgreens.com

One tried-and-true choice is this ADA-approved advanced whitening toothpaste from Colgate, a brand Dr. Wright recommends. Used as directed, it helps fight cavities, plaque, bad breath, and gingivitis in addition to gently polishing away surface stains.

Whitening toothpaste to try: Crest Pro-Health Extra Whitening Power Toothpaste

To buy: $3; target.com

Another great choice: this classic whitening toothpaste from Crest. It checks all the boxes (fluoride, whitening agents, ADA-approved) and also helps protect against tooth sensitivity.

Whitening toothpaste to try: Tom’s of Maine Simply White Clean Mint Toothpaste

To buy: $5; target.com

If you prefer natural toothpaste, reach for this ADA-approved tube from Tom’s of Maine to help remove superficial stains. “Some natural toothpastes do not contain fluoride, however this one actually does,” says Dr. Levi.

Tray-based teeth whiteners: What to know

Looking for something a bit more powerful than an over-the-counter whitening kit but aren’t ready to shell out for a full in-office bleaching procedure? You may want to consider tray-based whiteners. To buy, you’ll need to book an appointment with your dentist to be fitted for customized trays, which you’ll then fill with whitening solution and wear at home.

“The appliance is custom-made for your mouth and is lightweight so that it can be worn comfortably while you are awake or sleeping,” says Dr. Wright. “It’s thin, so you should even be able to talk and work while wearing it.”

The trays are worn for longer periods of time than over-the-counter strips, usually about four hours daily for a few weeks.

The whitening solution typically contains bleaching agents and can lighten teeth by a few shades. These trays cost about $250 depending on your dentist’s office.

Professional in-office whitening treatments: What to know

For most patients, the most effective—albeit pricey—way to whiten teeth is to invest in a professional in-office treatment with your dentist. These services usually involve a hydrogen peroxide solution that’s applied to your teeth along with a light or laser to catalyze the whitening process.

“These products have higher concentrations of peroxide than over-the-counter products, and thus work faster than at-home bleaching systems,” explains Dr. Levi.

The downside: Professional teeth whitening can cost anywhere from $500 to $1,000, and you may also have some tooth sensitivity from the stronger formula.

Whitening mouthwash and chewing gum

While it doesn’t hurt to use a brand of mouthwash or chewing gum that claims to help brighten teeth, the experts we spoke to agreed that you probably won’t see any real results from these types of products.

“Discoloration of your teeth is mainly surface stains and changes from aging,” explains Dr. Wright. “It takes contact time from these [whitening] agents to remove the discoloration, so the quicker the application of product, the less effective it is.”

In other words, swishing mouthwash or chewing on gum for a few minutes isn’t long enough for whitening ingredients to make any noticeable changes to your teeth.

There is one upside from chewing gum, though: “It increases saliva flow, and this could prevent stains from forming,” says Dr. Wright.

Can the foods you eat make a difference?

You already know that red wine and black coffee can reverse the effects of your newly brightened teeth. But other lesser-known foods can also affect your smile, including chocolate, blackberries, diet soda, white wine (it’s acidic, which can erode tooth enamel), dried fruit, and super-starchy foods like mashed potatoes and potato chips (they can get trapped in the teeth).

Chewing gum, sipping on water, or brushing your teeth right after eating can help minimize the stain potential of these foods.

Got sensitivity?

If you have sensitive teeth, it can be physically uncomfortable to use a whitening product, especially a strong one. Regardless of what method you choose, the higher the percentage of whitening ingredient a product contains, the greater the risk that it will cause you to experience tooth and gum sensitivity, especially with bleaching agents like peroxide.

When using over-the-counter products, spacing out the frequency of use may help you control the amount of sensitivity you experience. “Take a day or two off from whitening—it won’t hinder the results,” says Dr. Wright. “Faster doesn’t mean a brighter smile.”

Dr. Wilson also recommends asking your dentist about products that contain the ingredient potassium nitrite, “a good additive to control sensitivity.”

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This article originally appeared on Health.com

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