Endodontics · single question
What is the most important ion in MTA (Mineral Trioxide Aggregate)?
Show answer and explanation
Correct answer: A. Tricalcium silicate
- A. Tricalcium silicate (Ca₃SiO₅) is the MOST IMPORTANT component/ion in MTA. When MTA sets, tricalcium silicate hydrates to form calcium silicate hydrate gel and releases calcium hydroxide — which is responsible for MTA's high pH (~12.5), antimicrobial activity, biocompatibility, and ability to induce hard tissue formation (dentinal bridge and cementum).
- B. Sodium is not a significant component of MTA.
- C. Calcium hydroxide is a PRODUCT of MTA setting (from tricalcium silicate hydration), not a starting ingredient — and the question asks for the primary ion in MTA itself.
- D. Aluminum is present in the form of calcium aluminate in some MTA formulations, but tricalcium silicate is the primary active component.