Dental shock refers to a slight damage to the periodontal membrane when the tooth is subjected to an external force, usually without a very obvious defect in the dental tissue, in which case it may manifest as a feeling of partial elongation of the tooth, such as an uncomfortable sensation of biting. Because there is periodontal membrane damage, the teeth may be slightly loose and the gums may ooze blood. The pulp vitality is inconsistently expressed after tooth concussion. Some affected teeth show no pulp vitality after tooth concussion, but the pulp vitality may return to normal after a few weeks or months. In other cases, the pulp may be viable after a concussion, but the pulp slowly becomes necrotic at a later stage, in which case root canal treatment should be considered.