Which luxation injury carries the WORST prognosis for pulpal survival?

Correct answer: D. Intrusive luxation

• A. Subluxation loosens the tooth without displacement — the PDL is stretched but the neurovascular supply is largely intact, and the prognosis is the best of the group.
• B. Lateral luxation displaces the tooth and usually fractures the socket wall, but the crush injury is less extensive than in intrusion.
• C. Extrusive luxation stretches and may sever the apical vessels, but the PDL damage is less severe than crushing; prognosis is intermediate.
• D. Correct. INTRUSIVE luxation (axial displacement of the tooth into the alveolar bone) has the worst prognosis of the luxation injuries. It crushes both the apical neurovascular bundle and the periodontal ligament against the socket wall, producing very high rates of pulp necrosis (near-universal in mature, closed-apex teeth), replacement resorption/ankylosis and marginal bone loss.

Note: Immature (open-apex) teeth have far better revascularization potential after intrusion than mature teeth, and are frequently allowed to re-erupt spontaneously.