Your teeth have nerves which can be irritated by cold temperature, especially ice. These nerves are hidden away in the deeper layers and roots of your teeth. When exposed, these nerves are set off by temperature changes. This may occur due to damage to the teeth from brushing too hard, teeth grinding, plaque build-up, acidic foods, vomiting. or trauma to the teeth. Diseases of the gums can also lead to tooth sensitivity, such as gum recession, and gingivitis.