Endodontics · single question
A tooth becomes gray/dark after anterior dental trauma. What caused the discoloration?
Show answer and explanation
Correct answer: B. Pulp necrosis → hemoglobin breakdown products (hemosiderin/iron sulfide) penetrate dentinal tubules
Post-traumatic gray/dark tooth discoloration is caused by pulp necrosis. When pulp tissue undergoes necrosis, red blood cells hemolyze and release hemoglobin breakdown products (hemosiderin, iron sulfide). These iron compounds penetrate dentinal tubules and discolor the dentin from within — producing the characteristic gray or dark discoloration seen radiating from the pulp.
- A. ❌ External staining causes surface color changes — not the gray internal discoloration from trauma.
- B. ✅ Pulp necrosis → hemoglobin breakdown → hemosiderin/iron sulfide in dentinal tubules → gray internal discoloration.
- C. ❌ Enamel fracture exposes yellowish dentin at the fracture site — not the gray discoloration spreading through the whole tooth.
- D. ❌ Fluorosis is a developmental defect — it is not caused or triggered by acute trauma.