A tooth abscess is a sac of infected material called pus in a tooth or the gums.

Abscess Between Tooth and Gum
Abscess tooth
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Bacteria cause a tooth abscess. It begins when bacteria invade and infect a tooth. This results in pus build-up. When the pus is unable to drain, an abscess results.

Conditions that allow bacteria to invade a tooth include:

  • Severe tooth decay
  • Break or crack in a tooth that lets bacteria invade the pulp
  • Failed root canal treatment