Teeth Whitening
What is teeth whitening?
Teeth whitening is the process of brightening the teeth using a special type of bleach (up to 6% hydrogen peroxide or up to 16% carbamide peroxide).
The bleach penetrates the enamel and dentine and breaks down into oxygen and water. The oxygen breaks down the double bonds of organic bonds which cause your teeth to discolour.
Whitening should only ever be carried out under the prescription of your dentist. This can be done:
- at home with whitening trays ("home whitening"), or
- in the dental surgery by a dentist, dental hygienist or dental therapist ("in office whitening")
What is the procedure?
Before embarking on any teeth whitening treatments, your dentist will check your mouth is healthy. This means no active decay or gum disease.
In most cases, your dentist will be able to determine the cause of your discoloured teeth. This can help them decide whether teeth whitening is a suitable treatment for you.
They will talk you through the risks of treatment (see below) and all the options so you can choose which option is right for you.
In office whitening
In office whitening, also known as "power whitening", can be completed in either a single long visit (about 2 hours) or multiple shorter appointments (30-60 minutes). The number of appointments will depend on the type of system your dentist uses.
The stages depend on the system being used and the dentist but in general, these are the steps:
- The teeth are cleaned to remove any plaque/bacteria.
- Retractors are used to hold the cheeks/lips out of the way. A protective gel is placed on the gums to act as a barrier and prevent them being irritated by the bleach.
- Your dentist will take photos or record the current shade of your teeth to act as a baseline.
- A thin layer of concentrated bleaching gel is painted on the surfaces of the teeth and leaving this on for 15-30 minutes before washing it off. Some dentists shine a bright light on the tooth which activates the gel.
- Step 3 is usually repeated 1 or more times until the desired brightness is reached.
- Your dentist/nurse will remove the retractors after the final round of gel is applied and you will be asked to rinse your mouth thoroughly.
- The new shade of your teeth will be recorded. This is likely to change slightly over the next few days as your teeth "rehydrate".
If you are not happy with the new shade of your teeth, your dentist may recommend further in office whitening appointments or home whitening trays.
Home whitening
It takes two appointments to get ready for whitening your teeth at home.
At the first appointment, your dentist will take impressions, or "moulds", of the top and bottom teeth. These impressions are sent to the dental lab to make custom-made trays for your mouth. These are a bit like mouthguards but much thinner.
At the second appointment, usually 1-2 weeks later, your dentist will make sure the trays fit your mouth properly. Once they are happy, they will give you bleaching gel and instructions on how to whiten your teeth at home. If the trays do not fit, they may need to be adjusted or re-made. A poorly fitting tray can cause damage to your gums if the bleach seeps out.
Your dentist will take photos or record the current shade of your teeth at either the first or second appointment. As you whiten your teeth, you can compare your progress against these.
After you have received your trays and bleaching gel, you can begin whitening your teeth at home. Most people wear their trays (loaded with a small amount of gel) whilst they are sleeping. You should follow the advice given by your dentist but, in general, these are the steps:
- Brush and floss your teeth.
- Make sure your bleaching tray is dry. Place a dot of bleaching gel inside the tray on each tooth (many bleaching trays have a small dip or reservoir for you to place the gel in).
- Dry your teeth either with a clean handkerchief, cotton swab or by sucking air into your mouth. This is an important step as the bleach won't work as well if the teeth are wet.
- Seat the trays, loaded with gel, in your mouth. Use your finger, clean handkerchief or cotton swab to remove any bleach which has seeped out of the tray onto the gums.
- Leave the trays in whilst you are asleep. If you'd prefer to whiten your teeth during the day then leave the trays in for 3-4 hours.
- When you wake up, remove the trays. Rinse your mouth and the trays with warm water. Spit the water out, do not swallow it. You should also brush your teeth as normal.
You should follow the above steps daily until you are happy with the result. You should avoid any staining products (tea, coffee, red wine, tobacco, etc) whilst you are whitening your teeth as it will slow the progress.
Your dentist will review you in 2-4 weeks to see how you're getting on. The change will happen gradually over 2-4 weeks*. The great thing about home whitening is you are in control of how "white" your teeth become.
*Some staining, such as tetracycline (antibiotic) staining, takes much longer to respond to whitening - possibly a year or more.
Internal whitening
Most people have their teeth whitened due to general yellow discolouration. If you have a single tooth which is discoloured due to a history of trauma and root canal treatment, this can be managed with a process called "internal whitening" or "non vital tooth whitening". This process is similar to home whitening with a few extra steps:
- Your dentist will take an xray and do some tests to check the quality of the existing root canal treatment and to check there is no sign of infection. If your dentist is concerned, they may suggest a re-root canal treatment prior to whitening.
- Impressions are taken for bleaching trays and these are fit 1-2 weeks later.
- At the same appointment your bleaching tray is fit, your dentist will remove the filling in the back of the tooth which has sealed the root canal treatment in place. A small amount of root canal filling is removed and replaced with a thin layer of temporary filling material. This will leave a hole in the back of the tooth which will stay open whilst you are whitening your teeth*.
- You should then follow the usual steps for whitening at home but only place the bleaching gel in the tray where the tooth is discoloured - your dentist will show you which tooth this is. You should also place a small amount of bleaching gel in the hole in the back of the tooth.
- Once you are happy with the result, your dentist will place a temporary filling in the back of the tooth. After 2 weeks, they will replace the temporary filling with a white filling (composite).
*This hole will collect food and bacteria so it is important to use a small brush (interdental brush, e.g. TePe, or single tufted toothbrush) to clean this. If you do not, there is a risk of the tooth becoming decayed and re-infected, and the whitening is unlikely to work.
What are the risks?
Teeth whitening is a safe procedure, as long as it is done by a registered dental professional. There are a few minor side effects you may experience when you whiten your teeth:
- Sensitive teeth
This is one of the most common complaints when people first whiten their teeth. This is a temporary side effect which will resolve 1-2 weeks after you have finished whitening your teeth.
To help manage sensitivity, you can use a desensitising toothpaste twice daily for 2 weeks before, during and after your whitening treatment. You can also alternate using desensitising toothpaste or tooth mousse in your tray one night and bleaching gel the next.
It is very rare for the sensitivity to be so severe that you cannot continue the whitening process. - Gum irritation
The gums can burn or blister if the bleaching gel is left on the gums for too long. This will self resolve after a few days.
With home whitening, gum irritation is most commonly happens if the tray doesn't fit properly, you placed too much bleach in the tray or you did not wipe away the excess gel. - Restorations do not whiten
Restorations such as fillings and crowns will not whiten or brighten. If the colour difference between these and your natural teeth bother you after your teeth are whitened, these will need to be replaced.
It is best to wait at least 2 weeks after completing the whitening process before replacing a white filling. This gives the teeth a chance to settle as there can be slight changes in the shade/brightness immediately after whitening and to ensure the white filling bonds strongly to the tooth. - Staining and relapse
Whitening is not a permanent fix. Over time, your teeth will gradually relapse (go back to) their original shade. This usually occurs over months and years. The process will happen more quickly if you smoke or drink a lot of tea/coffee/red wine.
The good news is, you can always whiten your teeth again with either home whitening or in office whitening. If you've had home whitening before and the bleaching trays still fit, you can usually get bleaching gel from your dentist to "top up" your whitening at home. - Whiter white spots
Sometimes the white spots on your teeth can look even whiter after your teeth have been whitened. For this reason, teeth whitening might not be the best option for you.
There are other treatments available such as resin infiltration (LINK) or microabrasion (LINK) which may be more suitable to manage your concerns. These can be used in conjunction with teeth whitening. - Failure to whiten
Very rarely, your teeth will not respond to whitening or will not whiten as much as you would like. In these situations, you may need to consider other options such as composite bonding or veneers.
For internal whitening, there is a small chance of "cervical root resorption". This is where the outer surface of the root just under the gum gets "eaten away" or dissolves. It is unclear why exactly this happens but it appears to be linked to high concentrations of bleaching gel (well over the legal maximum of 6% hydrogen peroxide) and history of dental trauma. In the early stages, it may be repaired with or without root canal treatment. If allowed to progress, the tooth may fracture and require extraction and replacement with a denture, bridge or implant.
There is no evidence or recorded cases of cervical root resorption occurring when whitening with low concentrations of hydrogen peroxide (<6%) or carbamide peroxide (<16%).
In office vs home whitening - which should I choose?
Many dental practices only offer home whitening. This may make the choice easier if you want to stick to your normal dentist for treatment.
If you are given the choice of in office or home whitening, I've outlined some of the key differences which may help you make a decision. Both in office and home whitening will give you a similar end result.
In office whitening
- Often needs only 1 or 2 appointments and results are seen immediately
- Not much hands on involvement from you as whole procedure is done by dentist at the appointment
- Long appointments
- More expensive (both initial and maintenance cost)
- Increased sensitivity
- Less control over final shade of teeth
- Not as easy to "top up" whitening when teeth stain/discolour again over time
Home whitening
- More appointments and takes 2-4 weeks (or longer) to see results
- Needs more involvement from you to whiten your teeth on a daily basis for best results
- Short appointments
- Cheaper (both initial and maintenance cost)
- Less sensitivity usually
- More control over final shade of teeth
- Easy to "top up" whitening when teeth stain/discolour over time as only need to purchase bleaching gel from dentist (as long as you have kept your trays and they fit)
Can my beautician whiten my teeth?
The simple answer is, no (unless they are also a registered dental professional working under the prescription of a dentist). Many beauty salons offer teeth whitening but this is illegal unless it is carried out by a dental professional under the prescription of a registered dentist.
As teeth whitening uses potentially hazardous chemicals, its use is heavily regulated by the General Dental Council. In 2012 a new law was passed stating that in the UK:
- The maximum concentration of hydrogen peroxide which can be used is 6%
- Whitening can only be legally carried out under the prescription of a registered dentist (you can check the GDC register to see the full list of registered dentists)
You can also buy home whitening products/kits online but these are not recommended for safety reasons. Many of these kits either contain such a small amount of bleach that they are ineffective or an extremely high concentration of bleach which makes them dangerous for use in the body.