A brighter smile is one of the simplest changes you can make to how you feel about your teeth. Professional whitening lightens the natural colour of your enamel using carefully controlled gels, under the guidance of a dentist who first checks that your teeth and gums are healthy enough for treatment. Many patients notice a clear difference after one appointment, although results vary from person to person and depend on the type of discolouration you have. On this page we explain why teeth change colour, who whitening suits, the options available, what happens during an in-clinic session and how to keep your results looking fresh.
Why teeth lose their brightness
Tooth colour comes from two layers. The outer enamel is slightly translucent, and underneath it lies dentine, which is naturally more yellow. The shade you see is a mix of both, plus anything that has settled on or inside the enamel over time.
Surface stains
Coffee, tea, red wine, cola, curry, berries and tobacco all leave pigments on the surface of the teeth. Enamel has tiny pores, and over months and years these pigments work their way in. A professional cleaning removes much of the loose surface staining, and whitening can then lift what remains deeper in the enamel.
Discolouration from within
Some discolouration starts inside the tooth. As we age, enamel gradually wears thinner and the darker dentine shows through more, so teeth tend to look more yellow over the years. Certain medicines taken in childhood while the teeth were forming, too much fluoride during that stage, or a knock that damaged the nerve of a single tooth can also change colour from the inside. These types of discolouration can be more stubborn. Whitening may still help, but sometimes other treatments give a more predictable result, and your dentist will talk this through with you honestly.
Is whitening right for you?
Whitening works on natural tooth structure. It is a good option if your teeth are generally healthy and you would like them to look lighter and more even, but there are a few points worth knowing before you decide.
- Whitening gels do not change the colour of veneers, crowns, bridges or tooth-coloured fillings. If you have visible restorations at the front of your mouth, they may stand out once your natural teeth become lighter and might need replacing to match.
- Gum disease, active decay, cracked teeth or worn fillings should be treated first, because whitening gel on unhealthy tissue can cause discomfort.
- If your teeth are already very sensitive, or you have exposed roots from receding gums, your dentist may suggest a gentler approach or some preparation beforehand.
- During pregnancy or while breastfeeding, whitening is not usually recommended, and your dentist may advise waiting until later.
- Whitening is generally not offered to children and young teenagers, whose teeth are still developing.
The best way to find out is a short examination. Your dentist will look at your teeth and gums, ask about your medical history and any sensitivity, and record your current shade so you can compare later. If whitening is not the right fit, they can explain other ways to improve the colour or shape of your smile.
Your options: in-clinic, home trays and shop-bought products
There are three main ways to whiten teeth, and each has its place. The right choice depends on how quickly you want results, how sensitive your teeth are and how much time you can give to the process.
In-clinic whitening
In-clinic whitening uses a stronger gel than you could safely use at home, applied by the dental team while your gums are protected. Because the session is supervised from start to finish, it is the quickest route to a noticeably lighter shade. It suits people who want a visible change in a short time, for example before an important event or while travelling for treatment.
Dentist-supervised home whitening
Home whitening uses custom-made trays that fit your teeth closely, with a milder gel you wear for a set time each day or night over a period of a few weeks. The change is more gradual, which some people find easier on sensitive teeth. The trays can also be kept for occasional top-ups later. Many dentists combine the two: an in-clinic session to start, followed by home trays to fine-tune or maintain the result.
Over-the-counter products
Whitening toothpastes, strips and kits are widely available. Toothpastes mainly polish away surface stains rather than changing the underlying shade. Strips and one-size-fits-all trays contain weaker ingredients and do not fit every mouth, so the gel may not reach all surfaces evenly or may touch the gums. They can work for some people, but without an examination there is a risk of whitening over problems such as decay, or of irritating the gums. If you are unsure, it is worth asking your dentist before you start.
What happens during an in-clinic session
An in-clinic whitening appointment usually takes around an hour or a little longer, depending on the approach used. Here is what you can generally expect.
- Check and shade record: your dentist confirms that your teeth and gums are ready and notes your starting shade with a shade guide or photograph.
- Cleaning: the teeth are polished to remove plaque and surface stains so the gel can work evenly.
- Protecting your gums and lips: a cheek retractor keeps your lips away from your teeth, and a protective barrier is painted over the gums and allowed to set.
- Applying the gel: the whitening gel is placed on the front surfaces of the teeth and left for a set period. Some techniques also use a special light alongside the gel.
- Repeating the cycle: the gel is removed and fresh gel is applied, usually several times, while the team checks on your comfort throughout.
- Final check: the barrier is removed, your teeth are rinsed and your new shade is compared with the starting point.
You can usually return to your normal day straight afterwards. Your teeth may look slightly brighter in the first day or two and then settle a little as they rehydrate, which is completely normal. Your dentist will give you aftercare advice and may suggest a follow-up session or home trays if you would like to go a little lighter.
Sensitivity and how it is managed
Temporary sensitivity is the most common side effect of whitening. Some people feel short, sharp twinges, especially with cold drinks, during treatment or for a day or two afterwards. Others feel nothing at all. Mild irritation of the gums can also happen if gel touches them, and it normally settles quickly.
There are several ways to keep you comfortable:
- using a toothpaste for sensitive teeth for a couple of weeks before and after treatment, if your dentist recommends it
- adjusting the strength of the gel or the length of each application
- applying a soothing or remineralising gel at the end of the session
- spacing out home whitening sessions, or pausing for a day or two if your teeth feel sensitive
- avoiding very hot or very cold food and drink for the first day or two
If sensitivity is strong or lasts longer than expected, tell your dentist. Lingering discomfort is not something you should simply put up with, and it can usually be eased.
How long results last and how to keep them
Whitening is not permanent, because the same habits that stained your teeth in the first place carry on afterwards. How long your result lasts varies from person to person. Some people stay happy with their shade for a long time, while others notice gradual fading sooner, particularly if they drink a lot of coffee, tea or red wine, or smoke.
For the first couple of days after whitening, your teeth can pick up stains more easily. Many dentists suggest a 'white diet' during this period, avoiding strongly coloured food and drink such as coffee, tea, red wine, cola, beetroot, soy sauce and tomato-based sauces.
After that, a few simple habits help you keep your smile bright:
- brush twice a day with a fluoride toothpaste and clean between your teeth daily
- rinse with water, or drink through a straw, after dark drinks
- cut down on smoking or, ideally, stop altogether
- keep up regular check-ups and professional cleanings to remove new surface stains
- use your home trays for short top-up sessions when your dentist suggests it
Whitening alongside other treatments
If you are planning veneers, crowns, bonding or other cosmetic work on your front teeth, the order matters. Ceramic and composite restorations keep the colour they are made in and do not respond to whitening gel. That is why dentists usually recommend whitening first. Once your natural teeth have reached the shade you like and the colour has settled, which typically takes a couple of weeks, the new restorations can be made to match.
Whitening can also be a useful step after orthodontic treatment, such as clear aligners, when your teeth are straight and you would like the colour to look fresher too. In a smile makeover it is often one of the simplest parts of the plan, and sometimes it is enough on its own to give you the change you were hoping for.
Planning your treatment
If you would like a brighter smile, the first step is a conversation and an examination. Your dentist will look at the health of your teeth and gums, explain which type of whitening suits you and give you a realistic idea of what to expect, since results differ from one person to the next. If you are travelling for treatment, let us know your plans in advance so the appointment can fit around your trip. Whatever you decide, the aim is simple: a natural-looking, healthy smile you feel confident sharing.
