Safe, Legal Whitening

The Rules in Short

In UK law, whitening teeth counts as practising dentistry, so only people on the General Dental Council register may do it. In practice that means a dentist, or a hygienist or therapist acting on a dentist's prescription.

Any whitening product with more than 0.1% and up to 6% hydrogen peroxide may be supplied only through a dental professional. Before the first use, a dentist has to examine you to make sure whitening is safe for you, and the first application must be done by the dentist or under their direct supervision. Under-18s are excluded unless the aim is to treat or prevent disease, and concentrations above 6% cannot legally be used at all. Strips, pens and other products sold directly to shoppers may contain no more than 0.1%, which limits them largely to surface stain; they cannot meaningfully lighten the tooth.

The Trouble with Salons and Kiosks

Whitening in a beauty salon, at a shopping-centre stand or at a pop-up event, carried out by anyone not on the dental register, is illegal, and the General Dental Council has brought prosecutions. The gels involved tend to be too weak to work or not legal to supply, and some rely on chlorine dioxide, an ingredient that can wear away enamel. Some operators try to sidestep the rules by asking you to put the tray in yourself, which makes it no more legal and no safer.

What is missing is an examination. Bleaching teeth that have decay, cracks or gum disease can hurt, and it hides problems that need attention. One-size trays let the gel spill onto the gums, where it burns, and if something goes wrong, no qualified clinician is responsible for fixing it. You can look up anyone offering whitening on the GDC's online register in a minute or two.

What Professional Whitening Involves

At Peninsula Dentists there are two systems to choose from, and both begin in the same way.

• A dental examination. Dr Pei looks for decay and gum disease and makes a note of any fillings, crowns or veneers, since those will stay the colour they are.
• A digital scan. Your trays are made from an iTero Element scan rather than putty, so they hug the teeth and hold the gel in place.
• Fitting. We try the trays in, demonstrate how much gel goes in each and how long to wear them, and note the shade you are starting from.
• Boutique. Professional gel in your trays for a short spell each day, normally over two to three weeks, followed by a review.
• Enlighten. Two weeks with the trays at home, then a finishing appointment in the practice, with a guaranteed B1 shade. We are an Enlighten Centre of Excellence.

Either way, the peroxide soaks through the enamel and breaks up the pigment molecules responsible for darker teeth, so the tooth lightens from within. Yellowish teeth tend to respond best; greyer teeth take longer, and we will explain what is realistic.

Is It Safe?

It is, when a dentist prescribes and oversees it with regulated gel. Short-lived sensitivity is the most common side effect and wears off after you finish, and trays made for your teeth keep the gel off the gums. Correctly used, professional whitening leaves enamel intact, and it has been part of everyday dentistry for decades.

Some people we will not whiten: anyone under 18, unless it is to treat a dental problem; anyone pregnant or breastfeeding, purely as a precaution; and anyone with decay or gum disease that has not yet been treated. Teeth that are sensitive already can usually still be whitened with a gentler routine, and our whitening sensitivity guide explains how.

Dentist Whitening or a Shop Kit?

Shop products are not hazardous in the way illegal salon treatments can be, but with only 0.1% peroxide they do little that a decent toothpaste cannot. If your natural shade is noticeably darker than you want, expect to be underwhelmed.

What Whitening Cannot Change

Restorations do not lighten. Crowns, fillings, veneers and bonding stay their current colour, so if you have any on the teeth that show, we will plan to refresh or replace them after whitening, and if new bonding or veneers are planned, whitening goes first. Certain kinds of discolouration are stubborn: a tooth that has darkened after its nerve died, and the banded grey staining that some childhood antibiotics cause, both respond less well, and we will tell you plainly at the consultation what is achievable. Since everyone responds differently, we show you a realistic target before you begin instead of promising a set number of shades. Enlighten is the one route with a fixed target, its guaranteed B1, and we confirm at your consultation whether your teeth suit it.

Keeping Teeth White

• Hold on to your trays and use top-up gel from the practice now and then
• Follow coffee, tea or red wine with a mouthful of water, and sip cold dark drinks through a straw
• Stay away from cigarettes, which bring stain back fast
• Brush with fluoride toothpaste morning and night
• Book regular hygiene visits with Stefanie Goodall, whose Airflow polishing lifts surface staining

Most people keep their new shade for a year or longer, depending on habits. Because the trays stay with you, a short top-up brings the colour back with no need for a fresh course. Our guide to keeping teeth white goes further.

What It Costs at Peninsula Dentists

Boutique home whitening costs £350, or £315 on a dental plan, and covers your examination, the scan and trays, the professional gel and a review appointment. Enlighten, with its guaranteed B1 shade, costs £650, or £585 on a plan.² Among the practices around Greenwich and SE London we checked in October 2026, home whitening runs from roughly £295 to £499 and Enlighten from £645 to £750, so both of ours sit towards the lower end. If you are having Invisalign or a composite bonding package, Boutique whitening is already part of it. There is no charge for a whitening consultation; the £40 deposit comes back once you have attended. More detail is on our whitening page.

Questions

This guide explains the options in general terms. Only an examination can tell you which of them suits your own teeth.