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 giromatic handpiece for endodontic instrumentation operates by a: \nSelect and explain. \nA. Rotating motion, B. Oscillating motion, C. Zig-Zag motion, D. All of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Classification of endodontic instruments according to method of use:\nGroup I: Hand-operated endodontic instruments\xa0\nExample: Broaches, files, reamers.\xa0\nGroup II: Nonrotary endodontic instruments\xa0\n\nEngine driven instruments:\xa0\n\n– Reciprocating or quarter-turn motion.\n–\xa0Vertical stroke along with quarter-turn motion.\n\nUltrasonic and sonic instruments\xa0\n\nGroup III: Rotary endodontic instruments used with a handpiece\n\nSlow speed rotary stainless steel instruments.\nNiTi rotary instruments.\n\nKey concepts\xa0\nCommonly used reciprocating handpiece is Giromatic handpiece. It rotates with quarter-turn motion at 3000 rpm.\nSince this motion (quarter turn to and fro\xa0oscillation) resembles motion of steering of a ship, it is called Giromatic.', 'role': 'assistant'}]