How does teeth whitening actually work?
Whitening gels contain either hydrogen peroxide or carbamide peroxide, which breaks down into hydrogen peroxide in the mouth. The peroxide passes through the enamel into the dentine underneath and breaks apart the large stained molecules that have built up there over years of tea, coffee, red wine and simple time. Smaller molecules reflect more light, so the tooth reads as brighter. Nothing is scraped off and no structure is removed.
This isn’t new chemistry. Peroxide gels have been used in dentistry since the 1980s, and carbamide peroxide goes back to the 1960s, when it was first used in newborns for the management of thrush. That long record is the main reason we can talk about safety with some confidence. What has improved is the delivery: better gels, gentler concentrations worn for longer, and trays that genuinely fit.
What does the law say about whitening products?
This is where a great deal of harm happens. Under the cosmetic products regulations, only products containing up to 0.1 per cent hydrogen peroxide may be sold directly to consumers. Anything stronger may be supplied only through a dental professional, and the first treatment cycle must follow an examination by a dentist. The shop bought kits, the salon whitening and the whitening pens ordered from abroad are either too weak to work or are being supplied unlawfully.
The examination isn’t paperwork. It exists because peroxide applied over untreated decay, a leaking filling or inflamed gums causes real pain and real damage. Whitening is also for adults only. In the United Kingdom it must not be carried out on anyone under eighteen for cosmetic reasons. If a provider doesn’t want to look inside your mouth first, that alone tells you everything you need to know about them.
Does whitening damage your enamel?
Professionally supplied whitening, used at the recommended concentration and worn for the recommended time, doesn’t soften, thin or weaken enamel in any lasting way. It isn’t abrasive and it doesn’t strip a layer off the tooth. The evidence behind this is now several decades deep. What does damage enamel is acid, and some of the internet remedies people reach for instead, lemon juice, vinegar and bicarbonate scrubs, do exactly that.
Charcoal pastes deserve their own mention. They don’t whiten, they abrade. Any brightness is surface scratching, and over the years that scratching wears through enamel to the yellower dentine underneath, so the teeth end up darker than they started. Whitening done properly is one of the least invasive things in cosmetic dentistry. Done improperly, it’s one of the easiest ways to cause lasting harm.
Why do teeth get sensitive, and what helps?
Some sensitivity during whitening is common and it’s temporary. Peroxide moves through the tooth and can briefly irritate the nerve, which shows up as short sharp twinges, often to cold air or cold drinks. It settles within a day or two of stopping and it doesn’t mean damage has been done. Broadly speaking, the higher the concentration and the longer the wear, the more likely it’s to appear.
It is also very manageable. We can drop the concentration, shorten the wear time, move to alternate nights or take a few days off entirely. A desensitising serum can be applied to the teeth, and a prescribed sensitivity toothpaste used for a fortnight beforehand makes a real difference. Tell us early rather than pushing on quietly. Nobody wins a prize for enduring it, and a slower cycle reaches the same shade.
Who shouldn’t have their teeth whitened?
Whitening isn’t for everybody. It’s avoided in pregnancy and while breastfeeding, and it isn’t suitable for anyone with a peroxide allergy. It must not be carried out under eighteen for cosmetic reasons. Your mouth also has to be healthy first: untreated decay, gum disease, exposed root surfaces or a cracked filling all need sorting before any gel goes near a tray. That isn’t upselling, it’s sequence.
One other group tends to be disappointed rather than harmed. Whitening lifts the colour of natural tooth only. Existing fillings, crowns, veneers, bridges and implant teeth don’t change shade at all, so if you have a white filling across a front tooth it may look darker against newly lightened enamel and need replacing afterwards. We’ll show you this before you start, not after.
Why custom trays matter more than the gel
A custom tray is made from a digital scan of your teeth, so it holds a precise, thin reservoir of gel against the enamel and keeps it off the gum tissue. That’s what a good result actually depends on. A universal tray you soften in hot water leaks, which means gel on the gums, patchy coverage and a wasted fortnight. Fit, far more than the brand on the syringe, determines what you see in the mirror.
At LUSSO, professional whitening kit, gel and custom trays is £475 and includes the trays, the gel and the supervision. Replacement whitening gel afterwards is £250. Advanced whitening, for deeper or more stubborn discolouration, is £875. Every option is supplied only to adults after an examination, and each one is listed on our fees page and explained on the teeth whitening page.
How long do the results last?
Most people hold their result for one to three years, and how long depends almost entirely on what passes over the teeth. Red wine, coffee, tea, dark berries, curry, turmeric, ketchup and tobacco all put colour back. A top up every three to six months keeps things where you want them, which is why replacement whitening gel is £250 rather than the cost of a whole new course of treatment.
Teeth usually lighten noticeably within the first week, with most people seeing a clear difference by two weeks. Deeper discolouration, tetracycline staining or a tooth that has darkened after root canal treatment can take six to eight weeks and may need a different approach altogether. No honest dentist will promise you a particular shade before looking, because your starting colour and your enamel set the ceiling.
In short
Whitening is one of the safest and most rewarding things we do, provided it’s done properly, on a healthy mouth, by somebody who has examined you first. If you’d like to know what is realistic for your teeth, book a Dental Wellness Assessment and we’ll start from the shade you actually have.
