Endodontics · patient case question
Which material is used specifically to stimulate formation of a reparative dentine bridge?
Patient case: Deep caries on an upper premolar
Patient: Female, 36 years old
Chief Complaint: “Cold drinks hurt on my upper right, but it stops as soon as I swallow.”
Background: Healthy, no medications.
Findings: Tooth #4 has deep occlusal caries approaching the pulp with no radiographic periapical change; it responds sharply but briefly to cold and is not tender to percussion. Tooth #7 in the same patient is non-vital with a well-circumscribed periapical radiolucency; the excised soft tissue was submitted for histopathology.
Show answer and explanation
Correct answer: B. Calcium hydroxide
- A. Glass ionomer bonds to dentine and releases fluoride, making it an excellent base or liner, but it does not induce tertiary dentine formation.
- B. CORRECT. CALCIUM HYDROXIDE has a pH near 12.5. That high alkalinity produces a superficial zone of coagulation necrosis, and the irritation of the underlying odontoblasts and pulp stem cells drives differentiation and deposition of REPARATIVE (tertiary) DENTINE — the dentine bridge. It is also strongly antibacterial for the same reason. Its weaknesses are solubility over time and low strength, so it is placed as a thin liner and covered.
- C. Zinc phosphate is a luting cement with a low initial pH that can irritate the pulp — the opposite of what is wanted here.
- D. Zinc oxide eugenol is palliative and obtundent — eugenol sedates the pulp — but it does not induce a dentine bridge and eugenol inhibits resin polymerisation.
Note: Modern practice increasingly favours calcium silicate bioceramics (MTA, Biodentine) for direct pulp capping, with better long-term seal and comparable bridge formation. Calcium hydroxide remains the keyed answer for the classic dentine-bridge question.