Final answer:
Zinc Oxide Eugenol (ZOE) should not be used in direct pulp capping because eugenol can irritate the pulp tissue, possibly leading to inflammation or necrosis.
Step-by-step explanation:
Zinc Oxide Eugenol (ZOE) cannot be used in direct pulp capping because the eugenol irritates the pulp tissue. Direct pulp capping is a procedure where a material is placed directly over exposed dental pulp with the aim to facilitate healing and maintain pulp vitality.
Eugenol, a component of ZOE, has been found to be irritating to the pulp and can lead to inflammation or necrosis, hence, it's avoided in this treatment. Instead, materials like calcium hydroxide or Mineral Trioxide Aggregate (MTA) are preferred for their biocompatibility and ability to promote the formation of reparative dentin.