Teeth have a soft core called dental pulp. The pulp extends from the crown — the visible part of the tooth — to the tip of the tooth's root in the jawbone. The pulp contains nerves, blood vessels and connective tissue. When a tooth is cracked or has a deep cavity, bacteria can enter the pulp. Left untreated, bacteria and decaying material can cause a serious infection or a tooth abscess, leading to pulp death, bone loss and loss of the tooth itself. Signs and symptoms may include swelling around your face and neck, a hole in your tooth, toothache or tooth pain, gum swelling, and temperature sensitivity.