Let's start with a little science behind sensitivity. Enamel, the strongest substance in your body, protects the crowns of your teeth. Underneath the enamel lies dentin, a part of the tooth that is less dense than enamel and contains microscopic tubules. When your dentin loses its protective covering, the tubules allow hot, cold, acidic, or sticky foods to stimulate your nerves inside your tooth. This is what causes your discomfort when ingesting these foods.