Teeth whitening.

Why teeth change colour

Dentists usually group tooth discolouration into two kinds. Extrinsic stains sit on or near the surface of the enamel, while intrinsic discolouration lies within the tooth itself. Many people have a mix of both, and the type of staining makes a big difference to how well whitening works. A professional clean removes much of the extrinsic stain, which shows how much of the colour belongs to the tooth itself.

• Extrinsic: tea, coffee, red wine, cola, curries, smoking and some antiseptic mouthwashes
• Intrinsic: natural ageing, as enamel thins and the darker dentine beneath shows through
• Intrinsic: certain antibiotics taken while teeth were forming, or too much fluoride in childhood
• Intrinsic: a single tooth that has darkened after an injury or root canal treatment

What whitening can and can’t change

Whitening gels use peroxide to break down the pigments inside enamel and dentine. Yellowing from age and long-term food and drink staining often responds well. Grey banding from medicines, white or brown fluorosis marks and a single dark tooth tend to respond slowly, unevenly or not at all, and bonding or veneers may be discussed instead.

Whitening has no effect on fillings, crowns, veneers, bridges or dentures. If you have these near the front, they will stay their current shade while the teeth around them lighten, and you may want them replaced afterwards. Exposed root surfaces near the gum line also tend to lighten less than enamel.

Zoom in‑chair whitening

Zoom whitening is carried out at our surgery in a single visit of around 90 minutes. We place a soft retractor to hold your lips back and a protective barrier over your gums, then apply a professional-strength whitening gel and activate it with the Zoom lamp in several timed cycles.

You will be sitting with your mouth open for much of that time, so many people bring headphones and music or a podcast. In‑chair whitening can suit people who would rather not wear trays at home. Sensitivity can be more noticeable in the day or so afterwards because the gel is stronger and the treatment is concentrated into one session.

Take‑home whitening trays

For take-home whitening we take impressions of your teeth and have thin, custom trays made that fit closely around them. A close fit keeps the gel where it is needed and away from your gums. You then use a lower-strength gel in the trays at home, following the wear times we give you.

Most people see a gradual change over one to two weeks. Because you control the pace, you can skip a day if your teeth feel sensitive, or stop once you are happy with the shade. The trays can be kept and reused with fresh gel for occasional touch‑ups, provided your teeth haven’t changed shape through new fillings or crowns.

Managing sensitivity and gum irritation

Temporary sensitivity is the most common side effect of whitening. The gel passes through the enamel and can make the nerve inside the tooth more reactive to cold for a while. It usually settles within a few days of stopping. Mild gum irritation can also occur if gel touches the gums, and it generally fades quickly.

If your teeth are already prone to sensitivity, let us know before you start. Things that often help include:

• Using a toothpaste for sensitive teeth for a couple of weeks beforehand
• Shortening tray wear times or leaving a day between sessions
• Avoiding very cold food and drinks during the whitening period
• Calling us if sensitivity lasts longer than a few days

Shop‑bought kits and dentist-supervised whitening

In Australia, higher-strength whitening products are restricted to use by or under the supervision of a dental practitioner, so kits sold in shops and online generally contain lower concentrations. Some people get a result they are happy with from these products. Others find progress slow, or that one‑size trays and strips let gel sit on the gums.

The main difference with dentist-supervised whitening is the check beforehand. A tooth that is darker than the rest can be a sign of a problem with the nerve, and decay or receding gums can make whitening uncomfortable. Finding these first means whitening is used only where it is likely to help.

Who should wait before whitening

Whitening is generally not recommended for anyone under 18. Teenagers’ teeth have larger nerves and enamel that is still maturing, which can make sensitivity more likely. As a precaution, we also suggest putting whitening off during pregnancy and while breastfeeding, as there is little research on its use at these times.

We may recommend treating decay, gum disease or leaking fillings before whitening, and some people with very sensitive teeth or significant gum recession may find whitening isn’t a comfortable option. If you are planning new front fillings or crowns, it usually makes sense to whiten beforehand and let the colour settle for a couple of weeks, so the new work can be shade-matched to your teeth.

How long whitening results last

Whitening is not a one‑off change. Teeth gradually pick up stain again, and how quickly depends largely on diet and habits. Some people find their shade holds for a year or more, while regular coffee, tea, red wine or smoking can shorten that noticeably.

Many people keep their results with occasional top‑ups using their take-home trays, along with regular cleans to remove surface staining. Sticking to the gel and wear times we supply, rather than wearing trays more often, helps avoid unnecessary sensitivity. Whitening is usually treated as cosmetic, so many extras policies don’t cover it. It is worth checking with your fund if that matters to your decision.