Teeth whitening kits: what are they and do they work?

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Teeth whitening kits: what are they and do they work?

On this page you will learn:

Summary – use teeth whitening kits if you:

  • Are looking for impactful results or have heavy staining
  • Don’t mind a solution that requires a bit of effort
  • Don’t mind spending a bit more compared to other options

Home teeth whitening kits - overview

Price: €12–€50 depending on contents

How to use: Fix gel-filled tray to your teeth and wear for around 30 mins.

Number of treatments: Varies—4/5-day, 7-day, 2-week kits available

How often: Once daily for 4–14 consecutive days

What are they?

Teeth whitening kits are trays filled with whitening gel that you push up onto your teeth and leave for a period of time. They are a bit like mouth guards.

There are home teeth whitening kits and teeth whitening kits that dental clinics use.

Home teeth whitening kits have less whitening agent in them.

There are three types of teeth whitening kits:

  1. Kits with prefilled trays
  2. Kits with mouldable trays
  3. Kits with either type of tray and an LED light

Kits with prefilled trays include:

  • A one-size fits all tray already filled with teeth whitening gel

Kits with mouldable trays include:

  • A plastic tray that you heat up and mould to your teeth
  • Syringes with the whitening gel in them that you squeeze into the tray once it’s fitted to your teeth

Kits with LED lights

  • a pre-filled tray or mouldable tray with syringes.
  • An LED light that you attach to the kit to help the whitening process.

All kits will include instructions.

Most kits will include a shade guide so you can track your progress.

How do kits whiten your teeth?

Pre-filled and mouldable

The whitening agent (normally hydrogen peroxide) starts working as soon as it makes contact with your teeth. It bleaches your teeth and any stains.

Trays tend to stay in contact with your teeth better than strips so are arguably more effective.

Kits with LED lights

LED lights are said to enhance the effect of the hydrogen peroxide, leading to whiter teeth.

What’s in the gel:

Manufacturers use different ingredients. The main whitening agent is normally hydrogen peroxide or, in non-peroxide products, a sodium compound such as sodium chlorite or sodium bicarbonate. Some will also have an activator that helps encourage the whitening process.

Here a few ingredients lists of a number of teeth whitening kits: 

iwhite instant teeth whitening kit:

Aqua, Hydrated Silica, Glycerin, Phthalimido-peroxy-caproic Acid, Sorbitol, Chondrus Crispus Powder/ Hydrated Silica, PEG-40 Hydrogenated Castor Oil, Aroma, Acrylates/Acrylamide Copolymer and Mineral Oil and Polysorbate 85, Citric Acid, Methyl Paraben, Calcium lactate gluconate, BHT, Xylitol, Potassium Acesulfame

hismile teeth whitening kit:

sodium bicarbonate, sodium chlorite, pomegranate, aloe vera, chamomile.

How to use – how often:

  • Most whitening kits take about 30 minutes to work
  • They are designed to be used every day for 4–14 days in a row.

The number of treatments provided varies from kit to kit. You can get five-day, seven-day or two-week treatments.

Remember that you need one tray for the top of your mouth and one for the bottom, so if a kit has 10 trays that means five treatments.

How to use – process:

Always follow the instructions. But the basic process goes like this:

Pre-filled tray:

  1. Brush your teeth gently.
  2. Remove the trays from the packaging.
  3. Take the top tray and put it in your mouth, lining it up against the bottom of your top teeth.
  4. Gently push the tray upwards onto your teeth.
  5. Repeat steps 3 and 4 with the bottom tray.
  6. Close your mouth. Don’t bite down hard on the trays as this can cause the gel to ooze.
  7. After the time specified in your product’s instructions, remove the trays and throw them away.
  8. Rinse your teeth and gums with water to remove any excess gel.

Tray with gels:

  1. Brush your teeth.
  2. Heat water—most products specify that you shouldn’t boil it, as this will compromise the tray.
  3. Place one mouth tray in the water for five seconds.
  4. Take the tray and immediately put it in your mouth. Bite down on it and press it against the front and back of your teeth until it fits snugly.
  5. Let it cool. If the tray isn’t moulded well to your teeth, repeat the steps above.
  6. Repeat steps 2–5 for the other tray.
  7. If the trays come with a tab on the end to hold it, cut this off.
  8. Make sure the trays are cool, clean and dry.
  9. Add a small amount of gel to the trays. The bottom should be covered but don’t put in so much that it will ooze up and get onto your gums.
  10. Put the trays into your mouth and push them onto your teeth. Wipe off any excess gel with a tissue to stop it damaging your gums.
  11. Keep the trays in for as long as instructed. This is normally around 30 minutes.
  12. Remove the trays and rinse your mouth to get rid of any excess gel. You may need to brush your teeth to get rid of all of it.
  13. Clean the trays.


Normally between €12 and €50, depending on what’s included in the kit. 

Pros – they are very effective

Kits are considered the most effective home treatment for whitening teeth. This is mainly because they are better at ensuring good contact between the teeth and the whitening gel.

According to Edmond Hewlett, D.D.S., a professor of dentistry at the University of California Los Angeles and spokesperson for the American Dental Association:

"You will see a noticeable difference, but final results can vary depending on individual teeth and the depth of staining or discoloration".

Home kits aren’t as good as professional kits

The levels of hydrogen peroxide in home whitening kits are much lower than those used at a dental clinic, so, again, you’re unlikely to get the same results as if a dentist whitened your teeth.

  • Home teeth whitening kits should contain no more than 0.1% hydrogen peroxide
  • Dentists can administer teeth whitening treatments with no more than 6% hydrogen peroxide

Cons – they require more work

  • Some people find the tray uncomfortable
  • They are a bit more work than pens, charcoal or strips

The best test teeth whitening kit—our top picks:

beam teeth whitening kit

Beam Teeth Whitening Kit

Price: €49.95

Time to work: one week

Number of treatments: four treatments

Benefits: Whiter teeth in one week / Peroxide-free and suitable for sensitive teeth

Buy now

iWhite Dark Stains Teeth Whitening Kit

iWhite Dark Stains Teeth Whitening Kit

Price: €29.99 (approx. €5 per treatment)

Number of treatments: Five treatments—works in 20 minutes

Benefits: Faster than some other kits / Special technology that absorbs dark pigments in your teeth

Buy now

Back to Teeth Whitening


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