Does whitening damage enamel? Five myths examined
The five claims about whitening we hear most often, and what the evidence actually says.
Teeth whitening attracts more misinformation than almost any other dental procedure. Here are the five statements we hear most.
"Whitening wears away enamel"
It does not. The active agent in whitening gels — hydrogen peroxide or carbamide peroxide — does not abrade enamel; it chemically breaks down the coloured molecules within enamel and dentine. The structure stays; the colour changes.
What does cause wear is prolonged use of abrasive "whitening" toothpastes, which lighten mechanically by scouring the surface rather than chemically.
"It works the same for everyone"
It does not. The effect is good for staining from tea, coffee and smoking and for age-related yellowing. For tetracycline staining, fluorosis and single dark teeth after trauma, results are limited or a different approach is needed. Starting shade, dentine thickness and enamel translucency all vary from person to person.
"My fillings will whiten too"
They will not. Composite fillings, porcelain crowns and veneers are unaffected by whitening gel. In patients with restorations on the front teeth, a colour mismatch appears afterwards and those restorations may need replacing. Discussing that beforehand is better than discovering it later.
"I can achieve the same with a supermarket product"
Over-the-counter products contain lower concentrations, and — more importantly — nobody has assessed the state of your mouth. Gel passing over an open cavity can reach the nerve; unsupervised application can burn the gum; stock trays overflow onto soft tissue and cause chemical irritation.
In many patients the discolouration comes largely from calculus and surface deposits — after a professional clean, whitening may turn out to be unnecessary.
"Do it once and it is permanent"
It is not. Staining foods and drinks and the passage of time gradually return the shade. A top-up every one to two years may be needed; keeping your take-home trays reduces that to a short application.
In short: whitening is safe and predictable in people found suitable after a dental assessment. The decision looks first at the health of the mouth, and only then at its colour.
