Which material is LEAST cytotoxic for repairing a root perforation?

Correct answer: C. Mineral trioxide aggregate

• A. Amalgam is dimensionally unstable at its margins, corrodes, and tattoos the adjacent soft tissue.
• B. Composite requires a dry, isolated field and effective bonding, neither of which is achievable inside a bleeding perforation.
• C. CORRECT. MTA is the material of choice for perforation repair. It is highly biocompatible, sets in the presence of blood and moisture — exactly the conditions inside a perforation — seals well, and is osteoconductive, so cementum and bone will form directly against it. Healing rather than chronic inflammation is the expected outcome.
• D. Zinc oxide-eugenol releases eugenol, which is cytotoxic to periodontal cells at the concentrations found adjacent to the material.

Note: Prognosis after perforation depends on three things: the LEVEL (crestal perforations are worst, because they communicate with the sulcus), the SIZE, and the TIME to repair. Seal immediately.