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': 'The lap sliding fit in cast restorations is provided by: \nSelect and explain. \nA. 2-5 degree divergence, B. Gingival bevel, C. Both, D. None', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The gingival bevel serves the following purposes:\u200b\n\nWeak enamel is removed. If the gingival margin is in the enamel, it would be weak, if not beveled, because of the gingival inclination of the enamel rods.\u200b\nThe bevel results in a 30-degree metal that is burnishable (on the die) because of its angular design. Bulky 110-degree metal along an unbeveled margin is not burnishable.\u200b\nA lap, sliding fit is produced at the gingival margin. This helps improve the fit of the casting in this region.\nWith the prescribed gingival bevel, if the inlay fails to seat by 50 µm, the void between the beveled metal and the gingival bevel on the tooth may be 20 µm; however, failure to apply such a bevel would result in a void (and a cement line) as great as in the failure to seat.\n\nSturdevant operative dentistry\xa07th Edition, Page No:e106', 'role': 'assistant'}]