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': 'Reverse bevel is indicated for all of the following cast materials except: \nSelect and explain. \nA. Class I, II, B. Cast ceramics, C. Class III, D. Class IV', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Reverse bevel is placed at the expense of the gingival ﬂoor, creating an internal dentinal plane inclining gingival - axially, locking the restoration and preventing proximal displacement. It always has a ﬂat dentinal transition between it and the proximal gingival level.\xa0\nIt can only be used when the gingival ﬂoor has suﬃcient dimensions to accommodate it without decreasing the resistance form of the restoration (ﬂat portion of the gingival ﬂoor). Ideally, reverse bevels are prepared using gingival margin trimmers.\xa0\nThis bevel is indicated for use with Class I, II and III cast materials and infrequently with Class IV. It is not\xa0used with cast ceramics.\n\n\u200bOperative dentistry Modern theory and practice M A Marzouk : Page no 319', 'role': 'assistant'}]