You’ve worked really hard to straighten your teeth. Of course you want them as white as possible, too- right? Well, there are some things you should know about stains and how to get rid of them. We’ll cover all the details!

The hard outer layer of your tooth is the enamel, which protects the dentin underneath. Anything you eat or drink can form a layer over the enamel, as can the plaque that builds up due to bacteria feeding on food and drink particles.

These stains that sit on top of your teeth are called extrinsic stains, as they are “outside” the tooth. Over time, though, anything that is not removed works its way into the enamel, which is porous. Once stains work their way down, they become intrinsic, or “inside” the tooth. While they may be harmless, they can be unattractive.

Extrinsic stains can be prevented and removed with abrasive and/or chemical techniques. Abrasive removal includes anything that physically scrubs at your teeth— a toothbrush, a dentist’s pick, toothpaste containing silica (a mineral), or charcoal products. Some abrasive products designed for whitening are *very* abrasive, so you need to be careful lest you wear down the protective enamel on your teeth. If you have sensitive or fragile teeth it may be best to stay away from abrasive whiteners or stain removers.

Chemical agents work on both extrinsic and intrinsic stains. As mentioned, enamel is porous, allowing stains to travel deep. This also allows cleaning agents to follow them, though, so there’s hope! Non-abrasive whitening products use either carbamide peroxide or hydrogen peroxide. In the mouth, carbamide peroxide breaks down into hydrogen peroxide and urea, which means that both methods use hydrogen peroxide as the active whitening agent.

In-office whitening treatments generally use 15-43% hydrogen peroxide gels, applied after a gentle tooth-scrubbing which gets at the extrinsic stains. These treatments take about an hour and can whiten 4-6 shades at once, though these strong whiteners leave some patients with sensitive teeth.

At-home tray treatments often use 10-20% carbamide peroxide in a gel that also contains other ingredients- the stronger ones include sodium fluoride to strengthen your teeth and reduce sensitivity. These treatments are put in clear trays made from molds of your teeth. They are worn for various amounts of time depending on the treatment- 30 minutes to overnight, for one to two weeks, and they can be very effective. There are also lower-peroxide formulations that can be used daily or several times a day to build up a whitening effect over time without the risk of increased sensitivity. These include EverSmile WhiteFoam and AlignerFresh!

If you already have trays in the form of clear aligners or retainers, you can often use these with whitening products-- there's no need to purchase new trays just to whiten!

There are also at-home treatments available over the counter, with similar gels and generic trays or with hydrogen peroxide-containing polyethylene strips. These are easy to use and often effective, but the strips and trays are generic and may not cover everyone’s teeth properly.

Tooth whitening is generally considered safe and effective. 10% carbamide peroxide- equivalent to 3.6% hydrogen peroxide- has not been shown to cause any damage to tooth enamel. Higher concentrations, such as those available at the dentist, may weaken enamel. For this reason most of these formulas include fluoride to offset that effect. There are also prescription fluoride gels available for greater enamel protection.

For at-home whitening, sensitivity can be limited by using the product for shorter durations or using the product less frequently. Fluoride can help. Gum irritation sometimes occurs as well, but is usually mild and temporary. Orajel and Bonjela can help in case of such irritation.

Sensitivity is caused both by the hydrogen peroxide and the dehydration that occurs during the whitening process. Office treatment using intense lights to promote more whitening can be particularly dehydrating and cause the greatest sensitivity. Gel treatments, whether from the dentist or over the counter, sit on the teeth and can cause a dehydration effect as well. Water-based treatments that are more liquid, such as EverSmile’s WhiteFoam, AlignerFresh, and WhitenFresh do not coat the teeth in the same way—this means that whitening is more gradual, but there is no increased sensitivity.

It is important to know that whitening treatments of any kind will NOT whiten porcelain crowns or composite tooth fillings. If you have visible crowns, whitening the teeth around them could make these crowns more apparent. Additionally, whitening works best on yellowing teeth and may not work at all on grey teeth.

Because the peroxide travels through the enamel, it IS able to whiten under attachments such as those used for aligner trays in Invisalign and Orthly treatments. The treatment will not whiten the attachments themselves, though it will prevent them from staining and/or eliminate stains that have accumulated on them.

What about whitening toothpastes? Toothpastes generally whiten via abrasion, scrubbing off staining materials. Some do contain peroxide, but toothpastes are not generally left on the teeth long enough for the peroxide to have an effect- most people brush their teeth for two minutes or less before rinsing, and even the shortest peroxide treatments last half an hour each.

No matter how you whiten, regular life with eating and drinking will slowly add color back to your teeth. Diligent hygiene and regular whitening maintenance with a gentle product can help your teeth stay their whitest. EverSmile’s WhiteFoam, AlignerFresh, and WhitenFresh all contain 3.8% hydrogen peroxide to break up staining agents before they have a chance to set in to your teeth. Whether you’re in aligners, braces, or just looking to keep your smile pearly, regular use can help your smile be its best and brightest!