A dental cavity is the most common cause of a toothache. A cavity is a hole in the outermost layers of the tooth. These layers, the white enamel and the yellow dentin layer below, serve to protect the inner living tooth tissue, called the pulp. The pulp is where the nerves and blood vessels reside. Cavities are caused when bacteria in the mouth convert simple sugars into acid. The acid and saliva dissolve the enamel and dentin.
Often a cavity is not noticed by a patient until they deepen and collect food debris. The pulp of the tooth can become irritated by the bacterial toxins and, reactive to hot, cold, sour or sweet, thus causing toothaches. Unchecked, the pulpal injury may result in the death of the pulp tissue, creating a dental abscess or tooth infection. a small swelling or gum blister may be present near the affected tooth. Tooth abscesses are a very serious dental emergency and must be treated immediately. Erupting wisdom teeth and periodontal (gum) disease can also cause significant pain and discomfort and should be evaluated promptly.