Why over-the-counter whitening keeps disappointing people

Strips, pens, LED kits, charcoal pastes, purple toothpastes. People buy them, follow the instructions properly, and then tell us nothing much happened.

That is not usually a failure of effort. It is what the law permits those products to contain.

The legal position, and why it explains everything

In the UK, tooth whitening is legally the practice of dentistry. It can only be carried out by a registered dental professional, and only on the prescription of a dentist who has examined you.

Products that contain or release more than 0.1 per cent hydrogen peroxide, up to a maximum of 6 per cent, may only be supplied to dentists. The first use in each course must be carried out by the dentist, or under their direct supervision, after which they can issue trays for you to continue at home. They may not be used on anyone under 18 except to treat disease.

Anything that can lawfully be sold to the public over the counter is therefore capped at 0.1 per cent hydrogen peroxide or equivalent. That is a fraction of a prescribed concentration.

This is the whole explanation. A 0.1 per cent product can lift some surface staining from tea, coffee, red wine and smoking. It cannot meaningfully change the underlying shade of the tooth, because it does not have the strength to. Nothing about the packaging changes that.

It is also worth knowing that products bought from overseas websites may exceed 6 per cent, which is illegal to supply here and is not a bargain. Higher concentrations used without an examination and without properly fitting trays are how people end up with chemical burns to the gums.

Why a shop-bought tray does not fit

Even with the right gel, delivery matters. A generic tray is made for an average mouth, so the gel pools where there is space and misses where there is not. You get patchy coverage, and gel sitting on the gums rather than on the teeth, which is the main cause of the burning sensation people describe.

Custom trays are made from a scan or impression of your own teeth. The gel stays where it is meant to be, on every surface of every tooth, and away from the gum margin.

What the examination is actually for

The examination before whitening is not a formality. It changes what happens next.

• Decay and gum disease are treated first. Peroxide on an untreated cavity or inflamed gums is uncomfortable and sometimes harmful.
• Fillings, crowns, veneers and bonding do not whiten. If you have any across the front teeth, they will stay the shade they are, and your natural teeth will move away from them. Sometimes the right answer is to whiten first and replace those restorations afterwards to match. You should know that before you start, not after.
• Some discolouration will not respond. Staining within the tooth from an old injury, a root-treated tooth, tetracycline, or fluorosis behaves differently from ordinary surface staining, and some of it does not respond to whitening at all. Those cases need a different plan.
• Sensitivity can be anticipated and managed. Sensitivity during whitening is common and usually temporary. Knowing your history lets us adjust the strength and the wear time rather than you abandoning the course halfway through.

Why the slower approach works better

Peroxide needs contact time to work through the enamel and break down the pigments held inside it. Increasing the strength to compress the process tends to increase sensitivity rather than the result.

Our take-home whitening runs over roughly two to four weeks depending on your course, wearing your custom trays for a set period each day. It is supervised, so if something is not going as expected we adjust it while it is happening.

What we will not do is put a number of shades on it. Starting shade, the cause of the discolouration and your own enamel all affect the outcome, and anyone quoting a guaranteed result is guessing. Your dentist will give you a realistic expectation at the assessment.

Whitening is also not permanent. It fades gradually, faster if you drink a lot of tea, coffee or red wine, or if you smoke. Most people top up occasionally using their existing trays, which is inexpensive once the trays are made.

What it costs

Teeth whitening at Sale Dental Spa is from £275 for a two-week course, and from £450 for a four-week course. That covers the assessment, your custom-made trays, the prescribed gel and supervision through the course. Your dentist confirms which course your teeth need at the examination.

A Smile Design consultation is free if you want to talk it through first. If the underlying shade is not the real issue, or whitening alone will not get you where you want to be, we will say so and go through the alternatives instead. See the teeth whitening page and our fees page, or book at sale-dental-care.portal.dental. You can also call us on 0161 969 7464.