Tooth decay is the main cause of toothaches for children and adults. Bacteria in your mouth thrive on the sugars and starches in the food we eat. The bacteria form a sticky plaque clinging to the surface of teeth. Acids produced by the bacteria in plaque erodes the enamel, creating a cavity. The first sign of decay may be a sensation of pain when eating something sweet, very cold or very hot. Other causes of a toothache can include an accumulation of food and debris between teeth, inflammation or infection at the root of the tooth or in the gums, trauma to the tooth, including injury or grinding the teeth, sudden fracture of the tooth or tooth root. A sinus infection can also be felt as pain in the teeth.
A toothache often requires some sort of treatment by your dentist.