Teeth grow and shrink as a result of extreme temperature fluctuations. Microscopic fractures may form over time, enabling heat or cold sensations to pass through to the nerves beneath the tooth enamel. This is usually not harmful but can be uncomfortable for some people. Sticking your tongue against a frozen ice cream cone will feel cool because the ice melts into the mouth creating a cooling sensation. As more ice cream is eaten, less warmth is retained in the stomach and intestines, causing the body to create more saliva which also becomes cold once it enters the mouth. The intense cold stimulus is felt by sensitive nerve endings located in the teeth. Eating hot foods and drinks can also be hazardous to your teeth. The heat from these products can cause or exacerbate existing tooth problems such as cavities or gum disease. It can also lead to the breakdown of collagen in the gums, causing them to recede away from the teeth. If you have any questions about what happens to teeth when they get hot, don't worry about it. However, if you experience pain when eating hot foods, see your dentist soon so any oral issues can be resolved before they become serious.