What tissue forms as a reparative response after several weeks of pulpal irritation by resin composites?

• A. Reparative dentin
• B. Sclerotic dentin
• C. Cementum
• D. Enamel

Answer: (A)

Prolonged irritation of the pulp from a resin-based composite triggers the pulp to defend itself by forming tertiary dentin. When the insult is strong enough to kill some odontoblasts, pulp stem cells respond by differentiating into odontoblast-like cells that lay down reparative dentin along the pulp-dentin border. This newly formed dentin helps seal the pulp from further insult, acting as a protective barrier. Sclerotic dentin is dentin with occluded tubules caused by aging or mild stimuli, not a new reparative tissue formed after pulp irritation. Cementum and enamel are not produced in response to pulpal irritation; cementum forms on root surfaces during development, and enamel forms before eruption. Therefore, the tissue that forms in this reparative scenario is reparative dentin.