In dental pulp irritation tests, where is the material placed and for how long is it left in place?

• A. Placed in class 3 cavities in human teeth for 4 weeks
• B. Placed on enamel surfaces of extracted teeth for 2 weeks
• C. Placed in dentin tubules of teeth with caries for 6 weeks
• D. In class 5 cavity preparations in intact, noncarious teeth of monkeys or other suitable animals, left in place for 1 to 8 weeks

Answer: (D)

The test looks at how dental pulp reacts to a material by placing it in a cervical (class V) area of intact, noncarious teeth in an animal model and leaving it there for a period of 1 to 8 weeks. This setup provides a controlled environment where the pulp and surrounding dentin are normal, and the material can be in contact with dentin tubules near the pulp without confounding factors from caries or extensive decay. The 1–8 week window allows observation of the range of pulpal responses—from initial irritation and inflammation to longer-term reparative changes like dentin formation—so histologic assessment can reveal biocompatibility.

Other options don’t fit because they either involve teeth that aren’t suitable for a living pulp response (enamel surfaces of extracted teeth), place the material in locations that don’t reliably expose the pulp (class III cavities or carious dentin), or use an animal model in a way that aligns with the standard, ethical pulp irritation protocol (intact, noncarious teeth with a class V preparation) and a defined duration that captures the expected pulp response.