Five common myths about tooth whitening

Whitening is one of the treatments with the most misinformation around it. We hear the five sentences below at almost every consultation.

1. "Baking soda and lemon whiten teeth"

Lemon is an acid, baking soda an abrasive. Together they thin the enamel; as enamel thins, the yellowish dentine beneath shows through more. A short-lived shine, then yellower and more sensitive teeth in the long run.

2. "Charcoal toothpaste is natural and harmless"

Activated charcoal removes stain by scraping; scraping leaves scratches in enamel that do not heal. Most charcoal pastes also lack fluoride. For stain, regular scaling and polishing do the same job without wearing enamel away.

3. "Once done, it's permanent"

Whitening lifts the shade a few tones, but tea, coffee, red wine and smoking recolour the tooth. Partial relapse within one to three years is normal; a short top-up is enough.

4. "Fillings and crowns whiten too"

Whitening affects only natural tooth tissue. If there are fillings or crowns at the front, their colour will not match afterwards and they may need replacing. This belongs in the planning conversation from the start.

5. "If it causes sensitivity, it's damaging the enamel"

Sensitivity during treatment comes from the gel temporarily opening the dentine tubules; it is not enamel loss and passes within days. Under a dentist's supervision the gel's concentration and time are set for your gums and teeth.

So what to do

The cause of the colour complaint is found at the examination first: surface stain, the enamel's own structure, or a single tooth darkened after a root canal. Each has a different answer, and whitening is the answer to only one of them.