Which dental material most effectively stimulates dentinal bridge formation?

Correct answer: C. Calcium hydroxide

• A. INCORRECT. Zinc oxide eugenol (ZOE) has a mild obtundent/soothing effect and provides a bacterial seal, but it does not directly stimulate odontoblast activity or dentinal bridge formation. Eugenol can be cytotoxic to pulp cells at higher concentrations.
• B. INCORRECT. Glass ionomer cement releases fluoride and provides good seal, but it is not the primary material known for inducing dentinal bridge formation. It is used for base/liner purposes and in ART restorations.
• C. CORRECT. Calcium hydroxide (Ca(OH)₂) is the classic material for stimulating reparative dentinal bridge formation. Its high pH (~12.5) creates an alkaline environment that induces differentiation of pulp stem cells into odontoblast-like cells, which then form a mineralized dentinal bridge. It is the traditional gold standard for direct pulp capping and pulpotomy in primary teeth.
• D. INCORRECT (partially). MTA (Mineral Trioxide Aggregate) is increasingly preferred over calcium hydroxide for direct pulp capping due to its superior sealing ability and biocompatibility, and it also stimulates dentinal bridge formation. However, in classic INBDE teaching, calcium hydroxide remains the answer for 'which material stimulates dentinal bridge formation,' as this is its defining mechanism of action. MTA is a newer alternative.