A dental abscess is caused by bacteria that get in the pulp of your tooth or in the gums surrounding the tooth. The pulp can become infected when you have a deep cavity Cavities The hard outer surface on your teeth is called the enamel. The pulp is deep inside the tooth and contains blood vessels and nerves. Bacteria can damage different parts of the tooth. Cavities... read more or a cracked tooth.
Your body attacks the infection with large numbers of white blood cells. The dead white blood cells become the pus that forms the abscess.
A dental abscess causes:
Eventually the abscess can break open, letting the pus drain.