Teeth whitening: what works, what doesn't, what's a scam

Whitening is the treatment patients ask about most — and the one with the most nonsense sold around it. Here’s the honest version, sorted by what the evidence says.

The only thing that whitens: peroxide

Tooth color lives partly inside the enamel. Anything that genuinely whitens must penetrate it — and the only widely proven agents are hydrogen peroxide and carbamide peroxide. Everything else is either stain removal (surface polish) or marketing.

Method	Does it work?	Typical result
In-clinic whitening	Yes	4–6 shades in one visit
Dentist take-home trays	Yes	3–5 shades over 1–2 weeks
Pharmacy strips (EU)	Somewhat	1–2 shades, front teeth only
Whitening toothpaste	Surface stains only	Back to baseline, not beyond
Charcoal powder	No	Abrasive; can worsen yellowing long-term
LED “light-activated” home kits	The gel does the work	The light is theater

Why the dentist version costs more — and when it’s worth it

EU regulations cap over-the-counter peroxide at 0.1%, versus up to 6% for professional treatment. That difference is most of the result. In-clinic whitening also comes with gum protection, a shade plan, and a desensitizing protocol — the things that make the difference between “brighter” and “brighter but ouch”.

If your budget is limited, dentist-supervised take-home trays are the best value per euro: professional-strength gel in custom trays, at roughly half the in-clinic price.

Who shouldn’t whiten (yet)

• Untreated cavities or gum inflammation — peroxide on an open cavity hurts badly. Fix first, whiten after.
• Crowns and fillings in the smile zone — they don’t whiten. Plan the shade before replacing visible restorations, not after.
• Under 18, pregnant, or breastfeeding — no safety data, so we don’t.

The question to ask before paying anyone

“What peroxide concentration will be used, and who checks my teeth first?” If the answer is vague or nobody examines you before treatment, walk away — that includes beauty salons, where whitening by non-dentists is illegal in most of the EU for good reason.

A checkup before whitening isn’t upselling; it’s the difference between a great result and a painful one.