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': 'A 7 year old female patient complains of multiple carious teeth and has the habit of frequent snacking, is fond of chocolates and does not brush twice daily. Intra-oral examination shows grossly carious deciduous mandibular molars and proximal caries with mandibular canines. Which type of finish line was used during the crown preparation in the restored  tooth shown in the post-operative radiograph of this patient? \nSelect and explain. \nA. Chamfer, B. Feathered edge, C. Chisel, D. Shoulder', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Adequately contoured stainless steel crowns have maintained function and the relationship of the\xa0primary teeth in the arch. The gingival margin of the preparation on the proximal surface should\xa0 be a smooth feathered edge with no ledge or shoulder present.\nThe stainless steel crown (SSC) is an extremely durable restoration. Children with extensive decay,\xa0large lesions or multiple surface lesions in primary molars should be treated with stainless steel\xa0crowns. Because of the protection from future decay provided by their feature of full coverage and\xa0 their increased durability and longevity, strong consideration should be given to the use of SSCs in\xa0 children who require general anesthesia.', 'role': 'assistant'}]