Tooth injuries may be described as uncomplicated and complicated. Uncomplicated injuries do not expose the pulp (tissue at the center of the teeth with nerves and blood vessels). This reduces the chance of infection and loss of the tooth. On the other hand, complicated injuries do expose the pulp to potential infection, which can lead to the death of the pulp. If the pulp dies, pus may begin to build up near the root tip in the jawbone. This is called an abscess, and it can damage the bone around the teeth.

Injuries to a child’s teeth often are classified by the damage caused by trauma. They include:

• Concussion. Minor injury to the periodontal ligament, which is a bundle of connective tissue fibers that anchors the teeth to the jaws. Typically, such injuries do not cause the tooth to be knocked out of alignment.
  
  
• Subluxation. Injury that causes a tooth to become loose in the socket without knocking it out of position.
  
  
• Intrusive luxation. Injury that causes the tooth to be pushed deep into the socket, sometimes to the point that the tooth is no longer visible. The tooth may appear knocked out.
  
  
• Extrusive luxation. Injury that displaces the tooth from its position.
  
  
• Avulsion. An injury that completely knocks a tooth out of place.