Foam toothpaste vs traditional paste — which actually cleans better?

Two categories share a shelf labelled toothpaste. They behave very differently in the mouth.

What each format is ¶

Traditional paste — a viscous gel of water, humectants (glycerin, sorbitol), silica abrasives, surfactants (typically SLS), and the active (fluoride, hydroxyapatite, or peroxide). High coverage; mechanical scrub; standard 10cl tube.

Foam (mousse) toothpaste — same chemistry, whipped or aerated. Comes out of the tube already light and bubbly. Lower abrasive load. Higher water content. Often premium-priced.

What changes in actual use ¶

• Coverage. Foam spreads across more surfaces per ml — better interdental and gumline reach. Paste tends to concentrate on the front faces unless you take 30 seconds to redistribute.
• Abrasion. Foam typically has RDA 30–60; paste 70–120. Foam is gentler on enamel; paste cleans extrinsic stain faster.
• Fluoride delivery. Roughly equivalent at the same labelled concentration. The whipping doesn't reduce the active.
• Taste/feel. Foam reads lighter, less medicated. Paste reads more familiar.
• Compatibility with electric brushes. Foam works better with sonic/oscillating brushes — less splatter, no over-foaming.

When foam wins ¶

• Sensitive teeth, exposed root surfaces, or recession history
• Gum disease history (gentler around inflamed tissue)
• People who brush hard (less abrasion compensates)
• Children (lower foaming, less swallowed paste)
• Whitening maintenance phase (low RDA holds enamel)

When paste wins ¶

• Heavy extrinsic stain (coffee/tea drinkers; need higher RDA to lift)
• Cost (paste is dramatically cheaper per use)
• People who associate "foaming" with clean psychologically
• Easier travel — paste tubes don't depressurize at altitude

The SLS question ¶

Sodium lauryl sulphate is the foaming agent in most traditional pastes. It's not dangerous, but it can irritate sensitive oral mucosa and is implicated in mouth ulcers for ~20% of users. Foam toothpastes more often use milder surfactants (cocamidopropyl betaine, decyl glucoside). If you get recurrent ulcers, try SLS-free for a month.

The foam isn't the cleaning. The surfactant is.

Cost honest take ¶

Foam pastes typically cost 2–3× traditional pastes per gram of active. The premium pays for the gentler abrasive, the cleaner surfactants, and the format. Whether that's worth it depends on whether you'd otherwise use a sensitivity toothpaste anyway.

Whipped or scrubbed — same active, different abrasion.

More: the two-minute ritual — the technique both formats rely on.

Disclaimer. Editorial, not medical advice.