If the tongue touches the tooth, it hurts, if it is a toothache, it may be caries, periapical inflammation, if it is a tongueache, it may be a mouth ulcer. 1. Dental caries: Dental caries is mainly caused by bacterial residue on the teeth that destroys the tooth tissues to form cavities, which in severe cases leads to the exposure of the tooth nerve, which is stimulated by the tongue when it touches the teeth, thus causing pain. 2. Periapical inflammation: Periapical inflammation may be caused by bacterial infection, or physical or chemical stimulation, due to inflammation stimulation, the tongue touches the teeth when there will be pain, and there will also be persistent dull ache, occlusal pain, swollen gums and so on. 3. Mouth ulcers: recurrent, traumatic mouth ulcers are more common, occurring in the lips, tongue, cheeks and soft palate, if the tongue mucosa is damaged, if the ulcer occurs in the tongue, touching the teeth to stimulate the tongue will appear pain. If the tongue touches the teeth and hurts, go to the hospital in time to see a doctor, and after clarifying the cause of the disease, actively treat it, so as not to delay the condition.