Which luxation injury causes the MOST severe damage to the periodontal ligament and pulp?

Correct answer: A. Intrusion

• A. CORRECT. INTRUSION drives the tooth axially into its own socket, crushing the periodontal ligament between root and bone along its entire length and simultaneously severing the apical neurovascular bundle. It combines the worst features of every other luxation, and carries the highest rates of pulp necrosis, ankylosis and inflammatory resorption of any injury short of avulsion.
• B. Concussion involves injury to the supporting structures with NO displacement or mobility — the mildest injury of the group.
• C. Lateral luxation displaces the tooth sideways with an associated alveolar plate fracture, damaging the ligament on one aspect but sparing the rest.
• D. Extrusion partially displaces the tooth out of the socket, tearing the ligament but crushing comparatively little of it; the prognosis is considerably better.

Note: Severity ranking: concussion < subluxation < extrusion < lateral luxation < intrusion < avulsion.