If the pulp receives an excessive stimulus, which type of dentin is formed in response?

When the pulp of a tooth receives an excessive stimulus, such as from caries, temperature changes, or trauma, the pulp can respond by forming reparative dentin. Reparative dentin, also known as tertiary dentin, is produced by the odontoblasts in response to injury or irritation. This type of dentin serves as a protective response to help insulate the pulp from further damage and is typically formed more quickly and irregularly than primary or secondary dentin.

Primary dentin is the main type of dentin formed during tooth development, while secondary dentin is formed more slowly throughout life and not in response to irritation. Therefore, they do not relate directly to the situation of excessive stimulus on the pulp. While some might confuse reparative dentin with tertiary dentin, in the context of pulp response to an excessive stimulus, "reparative dentin" specifically emphasizes its role as a protective mechanism and is the most accurate term to describe the dentin formed under these circumstances.