Why is calcium hydroxide contraindicated as the medicament for pulpotomy in a primary tooth?

Correct answer: A. It provokes chronic irritation leading to internal resorption

• A. CORRECT. The high pH of calcium hydroxide (around 12.5) is intensely alkaline and causes a superficial necrosis of the pulp stump. In PERMANENT teeth this triggers a reparative dentine bridge. In PRIMARY teeth the response is different — the richly vascular primary pulp reacts with chronic inflammation and recruits odontoclasts, producing INTERNAL RESORPTION that perforates the root and results in early tooth loss.
• B. It does not directly injure the developing successor; the problem is confined to the primary root.
• C. Grey discolouration is associated with MTA and with pulpal haemorrhage, not with calcium hydroxide.
• D. Setting time is not the reason for the contraindication — calcium hydroxide sets adequately.

Note: Primary pulpotomy medicaments: formocresol has been the historical standard, with MTA, ferric sulphate and sodium hypochlorite now widely used. Calcium hydroxide is reserved for permanent teeth.