Baking Soda and Your Teeth: What the Dental Evidence Shows

Baking soda has been in toothpaste for well over a century, which makes it one of the few home remedies that mainstream dentistry actually adopted rather than merely tolerated. The evidence is reasonable and the limits are clear — and the limits are the part that gets left out.

Why it works at all

Two things. It is a mild abrasive, so it physically removes the film of stained pellicle that coffee, tea, red wine and tobacco leave on enamel. And it is alkaline, which briefly neutralises the acids produced by plaque bacteria after you eat.

The abrasivity number

Dentistry measures how hard a paste scours using Relative Dentin Abrasivity (RDA). Anything under 250 is considered safe for daily use; most commercial toothpastes sit somewhere between 30 and 150. Pure baking soda scores in the region of 7 — remarkably low, and lower than a great many "gentle" pastes on the shelf. That is the genuinely useful finding here: it cleans stain at an abrasivity that does not chew through enamel.

"Low abrasivity" is not "no abrasivity", and technique still matters more than product. Scrubbing hard, with any paste, is how people wear notches into their teeth at the gum line.

What it will not do

It will not whiten teeth in the sense the word is used in advertising. Peroxide-based products bleach the tooth structure itself; baking soda removes what is sitting on top of it. If your teeth are naturally yellow-toned, or discoloured from the inside — trauma, tetracycline, age — no amount of bicarbonate will change that, and a dentist is the honest next step.

It also does not prevent decay. That job belongs to fluoride, which has the strongest evidence base in preventive dentistry. Swapping a fluoride toothpaste for a jar of baking soda is a clear downgrade, and it is the single most common mistake in this area.

If you want to use it

• Easiest route: buy a toothpaste that contains it. You get bicarbonate, fluoride and a formulation someone has actually tested. Look for a national dental association's seal of acceptance.
• Occasional paste, if you like. A little bicarbonate dampened into a paste, once or twice a week, used gently. Not as a replacement for your fluoride paste — in addition to it.
• As a rinse: half a teaspoon in a glass of warm water, swished and spat, is a long-standing way to reduce acidity in the mouth. Genuinely useful after vomiting, when brushing straight away risks scrubbing acid-softened enamel. Spit it out; do not swallow it.
• Do not mix it with lemon juice. A perennial internet suggestion, and a bad one — the acid attacks enamel and the fizzing does nothing for you.
• Not with braces or certain dental work. Ask your dentist first; abrasives and orthodontic adhesives are not always friends.

The taste problem

Plain bicarbonate tastes salty and slightly soapy, and that is the real reason most people abandon it rather than any dental consideration. Commercial pastes solve this. This is not a minor point: the best oral hygiene routine is the one you actually do twice a day.