Potassium Nitrate Mechanism — NDEB AFK MCQ
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Correct answer: A — Depolarisation of nerve fibres, preventing repolarisation and reducing nerve transmission
Potassium nitrate (5% in desensitising toothpastes) acts by increasing the extracellular potassium concentration around intradental nerve fibres. This depolarises the nerve and prevents repolarisation, blocking nerve signal transmission. Unlike tubule-occluding agents (stannous fluoride, calcium sodium phosphosilicate, strontium salts), potassium nitrate does not physically block tubules — it directly reduces nerve excitability. It requires 2-4 weeks of regular use for significant clinical effect.
Reference: Heymann – Sturdevant's Art and Science of Operative Dentistry, 7th ed., 2019