Teeth whitening is the most requested cosmetic treatment in the UK — and also the one surrounded by the most confusion. Shopping-centre whitening bars, TikTok purple serums, charcoal powders, beautician packages… some of it is harmless marketing, some of it is illegal, and some of it can genuinely damage your teeth. Here's the straight version.
The Boring Legal Bit
In the UK, tooth whitening is legally classed as dentistry. It can only be carried out under a registered dentist's prescription, and beauticians, salons and kiosks offering whitening are breaking the law, however professional the setup looks.
Dentist-provided whitening uses custom trays with one of three strengths:
- 6% hydrogen peroxide, worn 60 to 90 minutes once a day.
- 16% carbamide peroxide, worn up to 8 hours, often overnight.
- 10% carbamide peroxide, worn up to 8 hours, often overnight.
Shop-bought products are capped at a token 0.1% hydrogen peroxide, roughly sixty times weaker, which is why most strips and pastes disappoint. Anything stronger sold outside dentistry is unregulated, and that's where the horror stories come from: burned gums, stripped enamel and permanent sensitivity from products of unknown strength applied with no dental assessment.
This isn't dentists protecting their turf. Whitening gel on an unexamined mouth can hide a bigger problem — decay, gum disease, a dead tooth — and make it worse. The examination is the point.
What professional whitening actually involves
At the practice, whitening starts with a check-up: we make sure your teeth and gums are healthy and work out why your teeth are the shade they are, because staining from coffee behaves differently from worn down teeth or a darkened root-treated tooth. You might not need any whitening at all; a scale and polish may suffice!
Most of our patients use professional home whitening: custom-made trays from a scan of your teeth, with dental-grade gel worn for a couple of weeks at home. Custom trays keep the gel on the teeth and off the gums, which is exactly what a boil-in-the-bag tray from the internet can't do. Results typically last one to three years; as a rule, anything that would stain a white t-shirt (coffee, tea or red wine, for example) will stain your teeth. Top-ups are easy once you have your trays.
Common questions, answered honestly
Does whitening damage enamel? Not when done properly. A 2011 literature review concluded that "at-home tooth bleaching agents based on hydrogen or carbamide peroxide have no harmful effects on enamel and dentin properties". Some people get temporary sensitivity during treatment; it's manageable and it settles.
Will my crowns, fillings or bonding whiten too? No, and this catches people out. Whitening only works on natural teeth. If you're planning composite bonding or veneers, whiten first, then have the new work matched to your brighter shade.
Do whitening toothpastes work? They can lift surface stains, but they are often abrasive and can damage surface enamel over time.
Is whitening suitable for everyone? No, which is why you must have an assessment before each course of tooth whitening.
Resources
Ready for a brighter smile? Book a free 15-minute telephone or video consultation with Jack Dowling, private dentist in Newcastle; we'll check your teeth are healthy, advise on the shade you can realistically reach, and get your custom trays made.
Wondering what’s right for your smile?
Book your free consultation →