This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
[{'content': 'Calcium silicate based material is: \nSelect and explain. \nA. MTA, B. Geristore, C. Dieket, D. Retroplast', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Mineral trioxide aggregate was developed by Dr Torabinejad in 1993.\xa0\nIt contains tricalcium silicate, dicalcium silicate, tricalcium aluminate, bismuth oxide, calcium sulfate and tetracalcium aluminoferrite.\npH of MTA is 12.5.\n\nTextbook of Endodontics Nisha Garg 3rd Ed', 'role': 'assistant'}]