How does professional teeth whitening work?
Professional whitening uses a peroxide-based gel that breaks down stain molecules inside the enamel, lightening the tooth shade. Done under dental supervision — in the clinic, with take-home trays, or both — it is controlled and safe for enamel. Results vary from person to person and final shades are not guaranteed.
What whitening can and cannot treat
Whitening works on stains within natural tooth structure. It responds well to yellowing from age, tea, coffee and dietary staining. It works less predictably, or not at all, on:
- Greyish discolouration from certain medicines taken in childhood.
- A single dark tooth after root canal treatment or injury, which may need internal bleaching or a veneer instead.
- Fillings, crowns and veneers — these do not bleach, so restorations in your smile line may need changing afterwards to match.
This is why an examination comes first: it identifies the cause of discolouration and predicts whether bleaching is the right tool.
Are you a suitable candidate?
Suitability requires a clinical examination. Cavities, exposed roots, cracked teeth and gum inflammation must be treated before whitening, otherwise the gel can cause significant discomfort. Whitening is generally deferred during pregnancy and breastfeeding as a precaution, and patients with very sensitive teeth may need a desensitising preparation phase or a gentler protocol.
How whitening is done
- Pre-whitening check and cleaning: surface deposits and stains are professionally cleaned first, so the gel works on the tooth, not on plaque.
- In-clinic whitening: gums are protected with a barrier, and a stronger gel is applied to the teeth in supervised cycles within a single visit.
- Take-home whitening: custom-fitted trays and a milder gel are used at home over one to two weeks, at your pace.
- Combination: an in-clinic start followed by home trays for maintenance is a common approach.
Your starting shade is recorded so the change can be compared objectively.
Benefits, side effects and honest limitations
Whitening is one of the most conservative cosmetic treatments — no drilling, no permanent alteration of the tooth, and noticeable brightening for most suitable candidates.
Limitations deserve emphasis: results vary between individuals, and the final shade cannot be guaranteed. Temporary cold sensitivity is common and usually settles within days; mild gum irritation can occur if gel contacts the gums. The effect is not lifelong — shades gradually deepen again over months to a few years depending on habits, and top-up sessions are normal.
Aftercare and keeping the result
For the first couple of days, limit strongly coloured food and drink — tea, coffee, red wine, turmeric-heavy dishes, colas — and avoid tobacco, as freshly whitened enamel picks up stains more easily. Use a desensitising toothpaste if advised. Long term, good brushing, periodic professional cleaning and sensible staining habits protect the shade; occasional home-tray top-ups can refresh it.
What affects the cost of whitening
Fees are confirmed at your consultation and depend on:
- Whether you choose in-clinic whitening, take-home trays, or a combination.
- Any preparatory work needed first, such as cleaning or treating sensitive areas.
- The number of in-clinic cycles your shade goal requires.
- Top-up gel for maintenance, if you opt for it.
Frequently asked questions
Is teeth whitening safe for enamel?
Dentist-supervised whitening using appropriate concentrations is considered safe for enamel. Problems mostly arise from unsupervised or excessive use of high-strength products, which is why an examination and professional protocol matter.
How white will my teeth get?
That depends on your starting shade and the cause of discolouration. Most suitable candidates see a visible improvement, but the exact final shade cannot be promised, and chasing an unnaturally bright white is not advisable.
How long do whitening results last?
Typically months to a couple of years, depending on tea, coffee and tobacco habits and your oral hygiene. Periodic top-ups with home trays can maintain the shade.
Will whitening make my teeth sensitive?
Temporary sensitivity is the most common side effect and usually settles within a few days. It can be managed with desensitising toothpaste and by pacing the treatment. Tell the dentist if you already have sensitive teeth so the protocol can be adjusted.
Will my caps and fillings whiten too?
No. Restorations keep their original shade. If crowns, veneers or visible fillings sit in your smile line, the plan may include replacing them after whitening so everything matches.