Desensitizing ingredients in toothpaste work by either:
1. Depolarizing nerve endings to reduce transmission of pain; or
2. By blocking dentinal tubules; this prevents stimuli (e.g., cold drink or air) from causing fluid flow in dentinal tubules, thereby preventing nerve pain inside the tooth from being stimulated. Potassium nitrate is a common nerve desensitizing agent and stannous fluoride is popular agent that reduces sensitivity by occluding dentinal tubules.