Pediatric Dentistry · patient case question
Two years later the replanted tooth has developed a persistent gray-brown discoloration. What is the underlying cause?
Patient case: Avulsed Central Incisor on the Soccer Field
Patient: 8-year-old male
Chief Complaint: “His tooth got knocked out at soccer practice.”
Background: Healthy, immunizations current, no allergies. Tooth #8 was avulsed 35 minutes ago. The coach placed it directly into a container of Hank’s Balanced Salt Solution from the sideline kit. No loss of consciousness, no other injuries.
Medications: None
Vital Signs: BP 100/64 mmHg · HR 98 bpm · RR 20 · T 98.6°F
Findings: Empty socket at #8 with no alveolar fracture. The avulsed tooth is intact with a wide open apex and short root (approximately two-thirds formed). Adjacent teeth #7 and #9 are firm and respond within normal limits.
Show answer and explanation
Correct answer: B. Breakdown products of red blood cells within the dentinal tubules
- A. Incorrect. Endotoxins are inflammatory mediators, not pigments. They contribute to periapical pathosis but do not themselves color dentin.
- B. Correct. Trauma ruptures pulpal vessels and blood enters the dentinal tubules. Hemoglobin is degraded to hemosiderin and related iron-containing pigments, which stain dentin gray-brown and are visible through the translucent enamel.
- C. Incorrect. Leukocyte breakdown does not generate a chromogenic pigment in meaningful quantity, and it is not a recognized cause of intrinsic tooth discoloration.
- D. Incorrect. Excess fluoride during tooth development causes fluorosis — diffuse white opacities or, when severe, brown mottling with pitting. It would have been present since eruption and would affect multiple teeth.
Note: Post-traumatic discoloration does not by itself confirm necrosis. Some discolored teeth remain vital, and a proportion of gray teeth lighten over time. Base the endodontic decision on the full picture: sensibility testing, percussion, and radiographic follow-up.
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