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Sensitivity relief

Potassium nitrate

Also listed as KNO3, desensitising agent

The classic 'sensitive teeth' ingredient. It calms the tooth nerve over a few weeks of twice-daily use; the benefit is real but moderate.

Moderate evidenceTypical strength: 5% in toothpaste

What it is

Tooth sensitivity happens when exposed dentine lets cold, air or touch reach the nerve through tiny tubules. Potassium ions diffuse along those tubules and damp down nerve firing. It does not block the tubules, so relief builds gradually and fades if you stop.

Most desensitising toothpastes use 5% potassium nitrate, usually alongside fluoride.

How strong is the evidence?

Moderate evidence

An older Cochrane review of six small trials found reductions in measured sensitivity but not in patients' own ratings and called the evidence unclear. Larger network meta-analyses since (125 and 32 trials) found potassium pastes beneficial with moderate certainty, especially for touch-triggered pain, with stannous fluoride and some other agents at least as effective.

What it's used for, checked

Reduces tooth sensitivity

Holds up

Moderate benefit after 2-8 weeks of twice-daily brushing.

Repairs enamel or exposed roots

False

It acts on the nerve; it does not rebuild tooth structure.

Works well with

  • stannous-fluoride
  • sodium-fluoride

Who should be careful

  • If sensitivity is limited to one tooth, is sharp and lingering, or does not ease within about 4 weeks, see a dentist: it can mean decay, a crack or a failing filling.
  • Sensitive-teeth toothpastes are not intended for young children unless a dentist advises it.

The studies

Every citation is checked against its PubMed record.

  1. Potassium containing toothpastes for dentine hypersensitivity.
    Poulsen S, Errboe M, Lescay Mevil Y, Glenny AM · Cochrane Database Syst Rev · 2006 · Systematic review / meta-analysis

    Six small trials: potassium nitrate paste reduced sensitivity to air blast and touch at 6-8 weeks, but patients' own ratings did not improve significantly; the authors judged the evidence insufficient for clear support.

  2. Desensitizing Toothpastes for Dentin Hypersensitivity: A Network Meta-analysis.
    Martins CC, Firmino RT, Riva JJ, et al. · J Dent Res · 2020 · Network meta-analysis

    125 RCTs (12,541 patients). Compared with ordinary fluoride paste, stannous fluoride, potassium salts (alone or combined with stannous fluoride), calcium sodium phosphosilicate, arginine and strontium reduced sensitivity to at least one stimulus, with moderate-to-high certainty.

  3. Comparative efficacy of self-administered dentifrices for the management of dentine hypersensitivity - A systematic review and network meta-analysis.
    Pollard AJ, Khan I, Davies M, Claydon N, West NX · J Dent · 2023 · Network meta-analysis

    32 trials (4,638 adults) with standardised methods: twice-daily toothpastes containing stannous fluoride, potassium with or without stannous, or arginine can be recommended to reduce sensitivity pain.