Tooth pain or toothache usually refers to the pain occurring around the teeth or jaws. In most instances, toothaches are caused by either tooth or jaw problems, such as a cavity, a cracked tooth, an exposed tooth root, gum disease, disease of the jaw joint, or spasms of the muscles used for chewing. The severity of a toothache can range from mild to chronic and excruciating. The pain may be aggravated by chewing or by extreme cold or heat. A thorough oral examination, including dental x-rays, can help determine the cause, whether the toothache is coming from a tooth or a jaw problem.

Sometimes, pain around the teeth and jaws can be symptoms of diseases of the heart, such as angina or heart attack, or of the ears, such as inner or external ear infections, and sinuses, like air passages of the cheek bones. The pain of angina, which is due to the inadequate supply of oxygenated blood to the heart muscle because of narrowing of the arteries, usually occurs in the chest or arm. However, in some cases of angina, a toothache or jaw pain, are the only symptoms of heart problem.

Infections and diseases of the ears and sinuses can also cause toothache. Thus, evaluations by both dentists and doctors are sometimes necessary to diagnose medical illnesses causing toothache. Otherwise the common dental causes of toothache include dental cavities, dental abscess, and gum diseases, irritation of the tooth root, cracked tooth syndrome, temporo-mandibular disease, impaction, and eruption.

The most common cause of toothaches is however, dental cavities. Dental cavities are holes in the two outer layers of a tooth, called the enamel and the dentin. The enamel is the outermost white hard surface and the dentin is the yellow layer lying just beneath the enamel. Both layers serve to protect the inner living tooth tissue called the pulp, where the blood vessels and nerves reside. Certain bacteria in the mouth convert simple sugars into acidic solutions. The acid softens, and, along with saliva, dissolves the enamel and dentin, creating small holes, or cavities. Small, shallow cavities are not that painful and may go unnoticed by the patient. The larger deeper cavities tend to collect food particles. The inner living pulp of the affected tooth thus gets irritated by bacterial toxins or by foods that are cold, hot, sour, or sweet, causing toothache. Toothaches from these larger cavities are the most common reasons for visits to dentists.

Treatment of a small and shallow cavity usually involves a dental filling, using amalgam, composite resin or glass ionomer cement. However, in the case of a larger cavity, an onlay or a crown is capped on the affected area. Treatment of a cavity that has penetrated deep enough and injured the pulp requires either a root canal procedure or extraction of the affected tooth. Injury to the pulp can lead to death of pulp tissue, resulting in tooth infection, or dental abscess. The root canal procedure involves removing the dying pulp tissue, thus avoiding or removing possible tooth infection, and replacing it with an inert material. This procedure is used in an attempt to save the dying tooth from extraction and is very painful.