When the protective layer of teeth (enamel) is worn away or gums recede, the dentine underneath becomes exposed. When the exposed dentine comes in contact with hot, cold, sweet or sour food and drinks, it can trigger a sharp short sensation called tooth sensitivity. Sensodyne Rapid Relief is a daily fluoride toothpaste that acts rapidly against tooth sensitivity, while still providing the benefits of a regular paste like strong teeth and health gums. It starts to act rapidly by building a mineral-like layer over exposed dentine and within microscopic channels.