A bright smile results from removing surface stains, correcting underlying discolouration, or altering the tooth’s visible surface. Professional whitening with carbamide or hydrogen peroxide is the safest evidence-based method. Abrasive home remedies risk enamel loss. The key is matching the cause of discolouration to the correct treatment.
Tooth colour comes from two sources: extrinsic stains on the enamel surface and intrinsic discolouration within the dentine layer beneath. Extrinsic stains are deposited by tannins in coffee, tea and red wine, by tobacco and by certain mouthwashes containing chlorhexidine. Intrinsic discolouration is caused by factors such as ageing (dentine naturally darkens over time), tetracycline antibiotic use, fluorosis, or trauma to the tooth.
Identifying which type is present determines which treatment will actually work. A professional clean and polish will clear extrinsic stains effectively. Intrinsic discolouration requires either a bleaching agent that diffuses through enamel into dentine, or a restorative covering such as a veneer or composite.
Professional teeth whitening uses a peroxide-based gel, either hydrogen peroxide or carbamide peroxide, applied directly to the tooth surface. The peroxide molecule is small enough to penetrate enamel and reach the dentine layer, where it oxidises the pigment compounds responsible for discolouration. Enamel mineral content is not removed; the chemical reaction targets colour molecules, not tooth structure.
At Battersea Smiles, whitening is carried out with custom-fitted trays made from impressions of your teeth, ensuring the gel is distributed evenly and contact with the gums is minimised. Chair-side or in-clinic treatments use higher-concentration gels and produce faster results, typically noticeable after a single session. Take-home tray systems use lower concentrations applied over one to two weeks, with results that are equally effective but achieved more gradually.
The greatest risk to enamel does not come from professional-grade peroxide but from physically abrasive products. The Relative Dentine Abrasivity (RDA) scale measures how aggressively a product wears tooth surfaces. The accepted safe upper limit is RDA 250. Several charcoal-based toothpastes exceed this threshold, and daily use over months can thin both enamel and exposed dentine.
Lemon juice and bicarbonate-of-soda pastes, widely circulated as home remedies, lower the oral pH to a range where enamel begins to demineralise. Whitening strips sold without professional supervision may contain unregulated peroxide concentrations, and poor tray fit allows gel to pool against gum tissue, causing chemical irritation rather than effective treatment.
Some teeth, particularly those darkened by tetracycline or with intrinsic grey tones, do not respond adequately to peroxide alone. In these cases, restorative options provide a predictable colour outcome.
| Option | Best for | Approximate cost | Limitation |
|---|---|---|---|
| Professional whitening | Extrinsic and mild intrinsic staining | £300–£600 | Does not change existing restorations |
| Composite bonding | Localised discolouration, chips or small gaps | £200–£450 per tooth | Can stain over time; requires polishing |
| Porcelain veneers | Severe discolouration or multiple teeth | £700–£1,200 per tooth | Irreversible; requires enamel reduction |
Composite bonding places tooth-coloured resin directly onto the enamel surface without significant drilling. Porcelain veneers require a thin layer of enamel to be removed so the veneer sits flush, which makes the procedure permanent.
The decision depends on three factors: the cause of discolouration, how many teeth are affected, and whether existing restorations are present.
Evidence from peer-reviewed dentistry literature indicates that professionally supervised peroxide whitening does not permanently alter enamel hardness or mineral structure when used as directed. Temporary sensitivity occurs because peroxide causes a short-term change in the fluid within dentine tubules, not structural damage.
Correctly aligned teeth are easier to clean and have fewer overlapping surfaces where stains accumulate. Patients undergoing Invisalign treatment at Battersea Smiles often combine it with a whitening course at the end of treatment, so the final result addresses both alignment and colour at the same time.
Results from a professionally supervised whitening course typically last one to three years, depending on diet and habits such as smoking or high coffee consumption. Top-up treatments with custom trays can extend this indefinitely without the need to start the process from scratch.
Whitening toothpastes work by abrasion or by low concentrations of peroxide. Those with an RDA below 70 and added peroxide can remove light extrinsic staining, but they cannot alter intrinsic discolouration and are not a substitute for a professional whitening course.
In the UK, teeth whitening by a dental professional is restricted to patients aged 18 and over. This is governed by the Cosmetic Products Regulation 2013, which limits the supply of peroxide-containing whitening products to registered dental practitioners treating adults only.
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