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': 'Intracoronal retainer placed in the abutment teeth has the following disadvantage \nSelect and explain. \nA. It is unaesthetic, B. They cannot provide support and stability, C. Difficult laboratory procedure, D. Difficult to repair and replace', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Internal or precision attachments\nAdvantages:\n\nImproved aesthetics, by elimination of a visible retentive component and vertical support.\n\nDisadvantages:\n\nDifficulty in repair and replacing.\nGreater cost to the patient.\nInability to use in teeth having short clinical crowns and tissue-supported distal extension denture bases.', 'role': 'assistant'}]