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Do Teeth Whitening Strips Actually Work?

by | Mar 11, 2021 | Dental, Health

There are many ways to whiten the color of a person’s teeth, from professional grade to over-the-counter varieties.

Out of all these methods, whitening strips are the easiest to use. They can show visible results in as early as a few days, while the effects can last for up to four months.

But do teeth whitening strips work? Do they help or hurt?

The quickest answer to this is both. The strips do help to improve teeth color, but they may also produce harmful effects. Recent studies published by the National Library of Medicine show that bleaching performed by dentists gives better results than applying a whitening strip.

However, trips to the dentist are not always possible. Commitments to work, family gatherings or other matters may get in the way. The effects of a whitening strip may not be as satisfactory compared to professional dental cleaning, but it’s an option for people looking for a quicker and cost-effective solution.

Do Teeth Whitening Strips Help or Hurt in Any Way?

In general, teeth whitening strips are perfectly safe to use. Crest, a commercial brand that even boasts “recommended by dentists” in their tagline, is not making things up. However, even dentist-approved products may cause discomfort if used in the wrong way.

Are Teeth Whitening Strips Safe?

The chemical ingredients found in whitening strips are what determines if it is safe to use or not. For example, people should avoid strips that use chlorine dioxide—these variants may be very effective in improving the enamel’s color, but the actual process is very damaging.

Chlorine dioxide is a type of acid used in treating swimming pools. When used on the surface of the teeth, it scrapes off the enamel and wears it down.

Instead, a whitening strip that makes use of peroxide is the better option.

Peroxide is a common ingredient in most teeth whitening products because it’s known to be safe. When added in safe amounts, whether in carbamide peroxide or hydrogen peroxide, the compound effectively bleaches the teeth without causing harm. This chemical removes composites that cause teeth discoloration in a way that is not as aggressive as chlorine dioxide.

Do Whitening Strips Damage the Teeth?

Peroxides still have the potential to damage a person’s teeth, but this can be prevented if used in the right amount.

Most whitening strips contain about 14% hydrogen peroxide, which is considered to be a safe dose. However, it is very unlikely for someone to take precise measurements of ingredients. Labels can also be deceiving, especially if coming from an unknown brand.

To ensure that a person uses a safe whitening strip, the American Dental Association has given the ADA Seal of Acceptance to specific products considered to be effective and safe to use. It is recommended to check this seal when choosing to buy over-the-counter whitening strips.

How Do Whitening Strips Work?

Professional teeth whitening conducted at a dental clinic usually takes about an hour to finish. The dentist first places a gingival barrier on the patient’s mouth to protect the gums. Then, hydrogen peroxide gel is applied to improve the shade of teeth.

Whitening strips work similarly but without the dentist and the gum-protective apparatus.

To better understand how a whitening strip works, it is best to know what it comprises first.

What Are They Made Of?

The strips are made of polyethylene, a synthetic plastic used to make food containers and packaging such as plastic bags. The plastic is cut into small strips and coated with a thin layer of chemicals such as hydrogen peroxide or carbamide peroxide. Aside from the whitening agent, each strip is also coated with the following chemicals:

  • PVP, the adhesive polymer that makes the strip stick to the teeth
  • Pyrophosphate to shield against stains
  • Sodium saccharin for a light and pleasant taste
  • Sodium hydroxide for maintaining the strip’s pH balance

How do You Use Them?

After placing the strips on the top and bottom rows of the teeth, the coating of chemicals is transferred to each tooth’s surface. The whitening compound seeps into the enamel gradually over time.

As the peroxide penetrates the surface layer of the enamel, the molecules responsible for teeth yellowing are broken down and dissolved. It oxidizes the particles that cause discoloration, making the teeth appear whiter.

Depending on the brand, there is a set amount of time to leave the strips in place. Leaving them longer doesn’t translate to being more effective. It is crucial to follow the instructions provided by the manufacturer.

Whitening strips are designed to have great coverage. However, irregularities in tooth shape, as well as microcracks, can prevent the whitening agent from getting distributed thoroughly.

How Long Before You Can See Results?

Teeth whitening results become visible in a matter of days or within a week. Some brands advertise their whitening strips to work in a few hours, but buying their products is not advisable.

While there’s a chance that someone might see results that quickly, the risk of damaging the teeth in the process is too high. It may do more harm in the long run.

Pros and Cons of Whitening Strips

As with any form of product or method, it’s vital to understand both sides of the coin. Knowing both the good and the bad can help in deciding whether to use a teeth whitening strip.


There are many advantages to using this whitening method. These hosts of benefits are the reason why it continues to be a popular at-home solution:

  • Affordability: Compared to visiting a dental office, whitening strips are significantly more affordable. Over-the-counter strips like Crest 3D are also a lot less expensive than bleaching gel kits purchased from a dental office.
  • Ease of use: No special training is needed to use these strips, and the instructions from the packaging are not complicated to follow. While the recommended time to keep the strips in place varies, the rest of the steps are straightforward. Just peel off the covering, press the strips on each of the upper and lower teeth, and allow it to sit for the required time.
  • Easy to obtain: Prescription is not required to buy teeth whitening strips. Consumers can purchase them from pharmacies, supermarkets, and even convenience stores. Online retailers like Amazon also carry them.
  • Effective: Whitening strips may not be as powerful as bleaching gels used in dental offices, but they still give a very noticeable difference compared to other at-home whitening products or just brushing the teeth alone. Additionally, results can be seen within seven days and last for up to four months or more.

Side Effects

This method is not without its share of side effects. They aren’t life-threatening, but they still need to be considered when using strips to whiten teeth.

  • Uneven results: Since teeth are three-dimensional, a two-dimensional approach offered by whitening strips has flaws in coverage. Cramped or crooked teeth will make it hard for the strips to apply their coating to all the visible parts. It can result in uneven whitening. There’s also a possibility of strips being unable to cover the entire length of the teeth.
  • Gum irritation: Gum irritation usually happens when parts of the strip are pressed on the gums. The chemicals seep through the soft tissue of the gums and can cause irritation. This side effect is not unique to whitening strips, though, as it can also occur in a dental office while bleaching. As prevention, special care must be carried out when applying the strips to ensure that they don’t stick to the gum line.
  • Tooth sensitivity: Tooth sensitivity does not necessarily indicate damage, but it is a very unpleasant experience. Any person who has tooth sensitivity usually experiences pain to some degree when sipping a hot soup or having ice cream, and they might react similarly if the chemicals on the strip are too overwhelming. Switching to a milder brand can usually alleviate this.
  • Enamel changes: A whitening strip that contains chlorine dioxide wears down tooth enamel rapidly, which increases the likelihood of tooth decay. Strips containing hydrogen peroxide are considered safe, but using them longer than indicated in the instructions manual can cause harm to the enamel over time. Pressing a strip on a tooth that has cavities can aggravate its condition as well.

How to Use Whitening Strips the Right Way

Most of the common side effects of using whitening strips can be avoided if used correctly. Instructions on the packaging are not the same across all brands. There are steps that some instructions don’t include, such as brushing or rinsing.

Here is a list of common steps on how to use whitening strips and make them more effective:

  1. The instruction manual must be carefully read and thoroughly understood. It is a crucial step, especially when switching to another brand whose specific instructions could differ.
  2. Teeth should be brushed and cleaned before applying the strips. It will remove food particles and bacteria that can hinder the effectiveness of the whitening agent. In case fluoride toothpaste is used, at least 30 minutes should pass before using the strips.
  3. If necessary, someone can cut the strip to match the size of their teeth and ensure that it doesn’t stick to the gums.
  4. The surface of the teeth should be wiped dry using a clean towel or napkin. Then, the strip is to be pressed to the teeth, with the angle adjusted accordingly, so that it covers most of them. The gel side should be the one that must be in contact with the surface of the teeth.
  5. The strips should be allowed to work for the time specified in the instructions. Laying down on the back is recommended, as well as breathing through the mouth for the entire duration. This will help prevent saliva from interfering with the whitening process and help keep the mouth dry.
  6. Peel the strips immediately after hitting the allotted time. Leaving them longer will not speed up or intensify the whitening process.
  7. Rinse or brush the teeth. Mouthwash will help completely remove the whitening agent left on the surface of the teeth. The chemicals used to oxidize the stains are no longer needed and should not be left on the enamel.

These steps serve as a supplement to the manufacturer’s instructions—they aren’t a replacement. If followed in conjunction with the original instruction, the use of whitening strips is safe and effective.

When to Brush Teeth

Brushing the teeth before and after using whitening strips is recommended. However, if pressed for time, a simple rinsing after removing the strips will do. Brushing before applying the whitening strip is a requirement and should not be omitted.

Using fluoride toothpaste can make it harder for the whitening agent to work because it can block the enamel. As mentioned above, a 30-minute wait is ideal before using the strips. If time is limited, brushing with water can speed up the process.

Is Rinsing Necessary?

Rinsing is an important step after removing the strips. It helps get rid of any leftover chemicals on the surface of teeth that could result in tooth sensitivity. The preferred method is to use a mouthwash or rinse with warm water, but it’s still best to just brush the teeth after peeling off the strips.

How Often should you Use Whitening Strips?

It takes some time for whitening strips to work—results are often seen a few days later within a week of first using it. During the first few uses, whitening strips are usually applied twice a day. It’s still important to read the instructions, as some brands recommend different methods. When the desired shade of white has been achieved, the strip application can be reduced to just once a month.

Common Questions About Whitening Strips

With so many people using teeth whitening strips nowadays, there are plenty of questions by first-time and long-time users.

Are Whitening Strips Good for the Teeth?

The main benefit that teeth get when using these strips is purely cosmetic. While it can effectively remove stains and discolorations from tobacco or coffee, it does not necessarily contribute to teeth general health.

Do Whitening Strips Work on Yellow Teeth?

Whitening strips can work on yellow teeth to varying degrees. Professional-grade strips are far superior to their counterpart that can be bought over-the-counter, but some people can still get substantial results with a common drugstore brand.

The cause of yellow teeth greatly affects the effectiveness of a whitening strip—for instance, it cannot reverse age-related stains.

Why Do Teeth Look More Yellow After Using Whitening Strips?

The treatment should be stopped immediately as soon as teeth start to look more yellow. If the strips are being used for quite some time already, the enamel may have thinned out. It is best to go to the dental office and ask about this problem.

What Happens When Whitening Strips Are Left on Teeth Overnight?

Whitening strips should be placed on teeth during the time specified in the instructions only, which is usually just 30 minutes. Leaving it overnight doesn’t change the results—the chemicals will likely just be diluted by the saliva. The most harmful effects a person may experience include the possibility of ingesting hydrogen peroxide and the wearing down of enamel.

When Is the Right Time to Eat?

Waiting to eat until one hour after using the whitening strips is standard. Be wary of eating foods that may cause discoloration or stain the teeth. Someone who has just used the treatment should avoid tobacco and coffee for the next 48 hours; teeth are more porous during this period, and the teeth can be stained fairly easily, negating the treatment altogether.

Are Teeth Whitening Strips the Best Choice?

Whitening strips are a popular choice for achieving a pearly-white smile due to being both affordable and effective. While there are possible side effects, following the instructions carefully can help prevent any issues. A recommendation from a dentist will yield the best results, as he can suggest brands that will work well depending on the patient’s teeth condition.

Dental cleaning should never be replaced entirely by teeth whitening strips—white teeth do not always mean the teeth are healthy, and whitening strips are purely useful for cosmetic purposes.