Science.

How the ingredients work, what the trials measured, and where the evidence stops.

• How desensitising toothpastes are tested: Schiff air score, tactile probe and VAS explained
  Desensitising toothpastes are tested by provoking a sensitive tooth on purpose and writing down what happens, three ways: an examiner directs a short blast of air at the exposed neck of the tooth and grades the reaction
• How nano-hydroxyapatite seals dentine tubules: the mechanism, step by step
  Nano-hydroxyapatite seals a dentine tubule by settling into the open end of the channel and onto the dentine around it, where repeated brushing builds a deposit of the same calcium phosphate mineral the tooth itself is m
• How potassium nitrate is thought to calm a sensitive tooth, and why the mechanism is still unproven
  Potassium nitrate is thought to work by raising the potassium concentration around the nerve endings inside a tooth until those endings stop passing signals on, a working model that dates from the 1970s and has never bee
• The Cochrane review on potassium toothpastes: what it found, what it did not, and what has happened in the twenty years since
  The 2006 Cochrane review pooled six randomised trials of potassium toothpastes and found that the two instrument tests improved at six to eight weeks while the patients' own assessment of their sensitivity did not, and i
• What happens inside a dentine tubule when you drink something cold
  Cold at the surface of exposed dentine chills the fluid sitting in the open tubules; the fluid contracts, the column is pulled outwards, and the nerve endings at the pulp end of the channel read that movement as a short,