Teeth Whitening: Why It’s Worth Having Done at the Dentist

As a dental hygienist, I get this question a lot from my patients, as they are looking for any, and all ways to whiten their teeth. My patients want to know if they would be okay using a cheaper over-the-counter whitening method, or if having their teeth whitened professionally at the dentist is worth the price, and results.

Over-the-counter whitening solutions are not as effective as professional in-office treatments. Having a dental professional’s assessment addresses issues such as; rotated/crooked teeth, decay, dental work, gum disease, gum recession and diet which all affect the success and longevity of whitening.

In this post, I go over the most popular whitening products out there on the market, what works, and what doesn’t. I also go over all the things I tell my patients to do and what not to do before, during and after having a whitening treatment, be it at home or in the dental office.

Why you should think of having your teeth professionally whitened at the dental office

Having white teeth, and whitening treatments are a hot commodity. However, there are many things overlooked in the process of choosing a treatment method that can have a huge impact.

Before teeth are professionally whitened in office, the teeth are professionally cleaned, removing the calculus (also known as tartar) and surface stain.

Before and after a professional dental cleaning that I did

Calculus is calcified bacteria that are strongly adhered to the teeth and cannot be removed at home, and if not removed on a regular basis can contribute to gum disease. (Why regular dental hygiene appointments are so important.)

Calculus is porous and absorbs pigment from food and drink that we consume but also blood that comes from unhealthy/inflamed gum tissue.

Most of the stain on our teeth is actually on the surface, embedded in the calculus and whitening treatments will do nothing for removing it. I would hate to see people wasting money on things that frankly, won’t work.

Having a clean surface to work with, allows the active ingredients in the whitening product to;

  1. Have more surface area to penetrate the tooth
  2. A superior result of much whiter teeth

In-office whitening uses a much higher percentage of peroxide and can achieve significant results in a shorter period of time.

Your entire oral health will be looked at and discussed with you prior to having your teeth whitened. And they can provide you with an individual treatment plan that will work for you, and that… is priceless.

Also, any dental work that is in the mouth will not whiten. Crowns, veneers, bonding, fillings etc. And there is even some evidence that whitening products can start to break them down, potentially shortening how long the dental work will last for. This study expands more on how whitening can affect dental work.

Not to say that at-home teeth whitening doesn’t work, some products do work, and I even recommend these at-home treatments to some of my patients. But these are specific cases.

Some over-the-counter teeth whitening solutions will harm the teeth and cause irreversible damage. so choosing the right one is imperative.

I really want people to use safe and tested products on their teeth, that won’t damage them in the long run. 🙂

How do teeth whiten?

When peroxide comes into contact with the tooth surface, a chemical reaction occurs and the teeth are dehydrated. This allows the peroxide to break down into oxygen which reacts with the stains to break them apart and “bleach” them.

No other whitening agents will whiten the teeth, only hydrogen and carbamide peroxide will. (Carbamide peroxide contains hydrogen peroxide at a ratio of 1:3.)

Because the teeth become dehydrated during whitening treatment, it makes the tooth act as a sponge.

It will want to resorb, and rehydrate.

That is why it is very important to watch what you are eating and drinking during and after teeth whitening treatments. I go over this in more detail farther down in this post.

For this reason, teeth whitening is much more effective when done in a shorter period of time.

Imagine using a product that takes up to 3 months to be effective (whitening mouthwash), if you are using it every day your teeth will be in the dehydrated state for much longer, increasing the chance of developing cavities and wearing away the tooth surface.

What types of tooth stain are removed by professional teeth whitening?

There are 2 types of tooth stain and whitening treatments only really work against one of them.

Extrinsic and intrinsic are the two types of tooth stain.

Extrinsic stain (think the exterior of a house) is on the surface/outside of the tooth and can be removed by having a professional teeth cleaning.

Stain can also be absorbed into the soft plaque on the teeth. And flossing and brushing will help to remove it.

Again, having a dental cleaning prior to whitening will remove the extrinsic stain so the whitening solution will penetrate the tooth more and provide a better result.

The intrinsic stain (think inside of a house) is on the inside of the tooth. And can only be removed/lightened with a teeth whitening agent, either carbamide peroxide or hydrogen peroxide.

Intrinsic stain can occur when the teeth are developing under the gums and an antibiotic is taken (tetracycline antibiotic is the most common). These stains are harder to remove and will take more treatments to improve, and sometimes whitening will not work.

Pigments from food and drink can also be absorbed into the teeth. This happens when our mouth is in a more acidic state. When our mouth is acidic (can be from diet, saliva pH, and amount of bacteria), the teeth become softer because the acid is breaking down the tooth, dehydrating it. Then anything we consume that has pigment can be absorbed into the tooth structure.

The stain often occurs more around the margins of dental work. And can even start to seep under the dental work, with whitening treatments not being effective. The dental work will have to be re-done.

However, if you know that some dental work has to be re-done, it would be a great idea to whiten the teeth prior to getting the work done.

When the dentist does the work, they will colour match the dental work to the natural colour of the teeth. So then in the future, when you want to touch up your whitening, the dental work will be a threshold of where you want to be in terms of colour shade.

What are the dental office professional whitening solutions/products?

Having professional teeth whitening is much safer than doing it with over-the-counter products. Simply because you’re having a trained professional doing it, it’s a controlled environment, and all the important information is given to you so your treatment will have the best outcome.

In-office whitening is usually a couple of hours long and the dentist or hygienist will go over the entire procedure with you first, and review your medical history.

Your gums will be protected with a material that is a thick liquid, and it hardens when we use a bright light on it. This prevents any of the whitening solution from getting on the gums and whitening and irritating them.

Some in-office treatments use a light. There is evidence that the light actually does nothing to impact how white the teeth get.

Most often the professional in-office treatment comes with custom take home whitening trays. They can be used to touch up your whitening in the future.

Custom trays that are taken home are moulded for your teeth. These custom trays take away the issue that whitening strips have; is that they are one shape. If you have any teeth that are crooked, or the gum line is not at the same level, there will be sections of the teeth that will be missed and won’t whiten.

What are the different types of over-the-counter teeth whitening products?

Over-the-counter teeth whitening solutions can vary in effectiveness and performance. And a lot of the whitening solutions online do not work and they are endorsed by famous influencers. And the funny thing about some of the people seen using the product online have veneers, which do not whiten.

We have to be careful of what products are being advertised, and are they even effective and safe to use.

Over-the-counter teeth whitening products contain a very small amount of the peroxide that will whiten the tooth. And some don’t contain any.


The most commonly used strips are Crest Whitestrips. These are the only over-the-counter teeth whitening products that I will recommend to my patients.

I love talking to my patients about teeth whitening and giving them all the tools to have a successful teeth whitening session. I know that when people know how to do it properly, they can achieve the best results.

I don’t want my patients to buy things that will not work and will waste their money.

Whitening systems with light

There is no evidence that the light helps to whiten the teeth. And often it is a UV light that can damage the skin.

You can find these teeth whitening products in beauty stores, and all over social media and they should be avoided. Especially because the area where you put the whitening gel is large and bulky, increasing the chance of it leaking out, affecting the gums and potentially you ingesting it.

Whitening pens

Teeth whitening pens have become increasingly popular. I personally wouldn’t even bother with them, save the money! If you want to read more about whitening pens I linked a post I wrote below.

Related post: Hygienist Explains; Do Teeth Whitening Pens Actually Work?

Whitening toothpaste

Most kinds of whitening toothpaste are abrasive and won’t actually whiten the teeth, rather they abrade away the surface. Over time this can cause irreversible damage to the teeth.

Some kinds of toothpaste contain some peroxide but it is a lower amount and often takes many weeks and months to see a noticeable change.

I do have a story of a patient who came in to see me after not coming for a few years. His main complaint was how yellow his teeth were and how his whitening toothpaste wasn’t working.

When I assessed his teeth, the top front ones barely had any enamel left. And I told him the reason why his front teeth were looking yellow is that he had moderate to severe loss of enamel and the yellow dentin (the tooth layer underneath the white enamel) was showing through.

He asked me how this could happen. And I said it can happen when we have aggressive brushing, paired with an acidic diet , or overuse of a whitening toothpaste.

I could see the regret in his eyes as he told me he would scrub his teeth, focusing on the front ones 3 times a day with a whitening toothpaste.

I felt so bad for him when he asked me how he could get the enamel back, and I told him he couldn’t. Once the enamel is gone… it’s gone. And the only way to get a whiter smile would be to have veneers or crowns put on the front teeth.

You can see the yellow dentin showing near the gum line. This cannot whiten, and could cause severe sensitivity.

He was angry that the toothpaste packaging didn’t tell people this, and that if he had known he never would have used them.

The only time where I would ever recommend someone to use a whitening toothpaste is if they are prone to surface stains, maybe they’re a smoker, wine drinker, or coffee and tea drinker. And even then I don’t want them using it every day, only once in a while.

These reasons are the same reasons that I don’t polish my patient’s teeth that often, only if they need it. If you want to know if you should skip the teeth polishing at your next dental cleaning I linked the post below.

Related post: Why You Shouldn’t Have Your Teeth Polished at the Dentist

Whitening mouthwash

The main issue with whitening mouthwash is how disgusting they taste! I tried it once to test out all these over-the-counter whitening products and I literally spat it out right away and had instant regret of wasting my money on it!

Whitening mouthwashes usually contain a very low amount of the active ingredient and will take months to even get a shade whiter. I’m not the biggest fan of mouthwash to begin with, and usually, I tell my patients to skip it unless there is a concrete reason to use it.

Whitening gum

Whitening chewing gums will not whiten your teeth. They can help to stimulate our salivary glands so the saliva will help to rinse away any pigment on the teeth before it settles into the teeth and stains them.

Beauty therapists providing whitening treatments

I wasn’t too sure of where to put this information in this post because it doesn’t fall into either in-office professional treatment or over-the-counter.

But it is very important for me to touch on.

Have you ever walked through a mall and a store is offering “professional teeth whitening”? These aesthetic salons who offer this should not be.

There are people out there who are performing “professional” teeth whitening when they are not licensed, dental professionals. In some countries, this is illegal and not allowed, but in others, it is allowed.

Only dental professionals can diagnose dental diseases and issues.

And if this crucial step is missed, irreversible damage can happen, or you just end up wasting all of your hard earned cash.

Please take this advice and don’t receive teeth whitening from anyone who is not a dental professional.

What whitening product/solution is right for you?

You should talk with your dental professional before taking on any whitening treatments. But you can use what I have written in this post to help you decide which route you want to take to getting a whiter and brighter smile!

What to do before, during and after a teeth whitening treatment!

I don’t tell my patients that they cant do over-the-counter whitening solutions, but I give them crucial advice that is needed for them to get the best results possible. And this is the same for in-office treatment.


Everything that we eat and drink comes in contact with our teeth and has the opportunity to stain them.

When the teeth are being whitening, they are dehydrated making our teeth act as a sponge, soaking up even more of the pigment from our food and drink.

Foods to avoid

Anything that has a strong colour to it will not be your friend while your whitening and for a short period of time after the whitening treatment is done.

Food and drink to avoid during and right after whitening; Coffee, tea, red wine, chocolate, blueberries, spinach, blackberries etc.

Pigments will be absorbed into the tooth and can decrease the effects of the whitening and cause stain. Any food that has dark pigmentation can be absorbed.

You will want to avoid these foods and drinks for at least 48 hours after whitening your teeth. And if you do consume anything pigmented, rinse your mouth out right away with some water. It will help rinse away the pigment before it can absorb into the tooth surface.

Toothpaste to use

Prior to whitening your teeth, you will want to use a toothpaste that has potassium nitrate as one of the ingredients. What potassium nitrate does is it desensitizes the nerve of the tooth.

You will want to use this toothpaste for at least 2 weeks prior to whitening your teeth. However, to get the greatest benefit there is one very important instruction to follow.

DO NOT RINSE YOUR MOUTH out or consume anything by mouth for at least 30 minutes after flossing and brushing.

WHY is this so important? If you rinse your mouth out right after brushing your teeth, you will rinse away most of the potassium nitrate so it wont reduce the sensitivity from the teeth whitening.


It is normal to experience some sensitivity during and after whitening your teeth. Because teeth whitening can cause the nerve of the tooth to become hypersensitive.

Tip: If you have custom whitening trays, you can put some toothpaste that contains potassium nitrate into the trays and put them in your mouth like you would when you are whitening. Leave it for at least 15-30 minutes. The potassium nitrate will help desensitize the tooth.

If you don’t have custom whitening trays you can just put about a grain of rice-sized amount of toothpaste on your fingertip and gently rub it into the teeth that are sensitive. You will want to rub it into the teeth for at least 60 seconds. Sensodyne has a toothpaste called Rapid Relief and works extremely well in this situation.

If you want to read more about the science behind teeth whitening and for a more in-depth explanation, this study is the place to go.

How to avoid stain before it happens

The best way to have white teeth and keep them white is to prevent the stain in the first place. I go through the ways of how you can easily prevent stain in the article I linked below. 🙂

Related post: Snub Coffee Stains; Dental Hygienist’s Guide to White Teeth

Holly 🙂

Holly Verran RDH

I am a Registered Dental Hygienist in Ontario, Canada. I hold registration and good standing with both the College of Dental Hygienists of Ontario and the Canadian Dental Hygiene Association.

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