As soon as you inhale, your teeth hurt, which may be caused by cold air stimulation of the pulp nerves, and is commonly associated with dentin hypersensitivity, wedge-shaped defects, dental caries and pulpitis. 1. Dentin hypersensitivity: due to enamel loss or defects on the tooth surface, the dentin is exposed and the dentin tubules are stimulated when inhaling, causing pain. 2. Wedge-shaped defects: If you brush your teeth horizontally for a long period of time, it may lead to gum recession, and also cause wedge-shaped defects in the neck of the teeth, where the dentin is relatively thin, and when you inhale, the cold air will go through the dentin and reach the pulp cavity, which will cause the symptoms of toothache. 3. Dental caries: If dental caries is more serious, resulting in deep holes in the teeth, it can also trigger inflammation of the dental nerve, a breath toothache. 4. Pulpitis: If you suffer from pulpitis, injuring the nerve of the tooth, you will also have a toothache when you breathe in. If you have a toothache when you breathe in, it is recommended that you go to a regular hospital dentist as soon as possible to determine the type of dental disease and standardize the treatment as soon as possible.