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': 'Main drawback of calcium hydroxide apexification compared with MTA: \nSelect and explain. \nA. More treatment time, B. Incomplete apical barrier, C. Incomplete coronal barrier, D. Reduced physical strength of dentin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Apexification with calcium hydroxide is almost similar when compared with MTA about given options, except achieved physical strength of dentin, which is comparatively less in Ca(OH)2.', 'role': 'assistant'}]