A toothache can be a sign of an infection or of inflammation. A tooth that aches also is usually sensitive to sugar, cold foods, heat or pressure. The pain level of a toothache can range from mild to severe. If a toothache is not treated it can get worse.
Tooth decay is caused by bacteria that lives in plaque. The bacteria sticks to tooth enamel. It uses sugars and starches from food to make acids that dissolve important minerals in the enamel. Results of decay include holes, weak spots and the destruction of the outer surface of a tooth. When the decay reaches the middle layer of the tooth it causes inflammation and creates a toothache.
Pulpitis occurs when the pulp of the tooth becomes inflamed, causing pressure on the nerve and affecting the tissue around the tooth. In most cases, pulpitis is a result of a trauma, such as repeated dental procedures or hitting your tooth on an object.
An abscess is an infection in the throat, face or mouth that starts out as a tooth infection. Bacteria from the tooth infection reach the gums and then the throat, cheeks and jaw, resulting in severe pain for the patient. In some cases, the infection can reach the facial bones.
If tooth enamel is lost, nerve endings inside the tooth can be exposed, causing severe pain. Changes in temperature, e.g. going from hot to cold weather, can irritate the nerve endings. Such changes cause fluid in the tubules to circulate. The movement of fluid pulls on the nerve endings, causing pain. Sweet and sour foods also can irritate the nerve.
Gum disease is also a serious infection that can cause severe pain if left untreated. This chronic bacterial infection grows in the gums and reaches the bones that support the teeth. The gums can become so inflamed that a tooth's roots are exposed, making the tooth sensitive to food.