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': 'In balanced force technique used for canal preparation: \nSelect and explain. \nA. Apical force is applied, B. Lateral force is applied, C. Both the forces are applied, D. No force application', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Balanced force concept uses Flex-R ﬁle and is described as "Positioning and pre-loading an instrument through a clockwise rotation and then shaping the canal with a counterclockwise rotation".\xa0\nMany authors discovered that greater risk of instrument damage was associated with clockwise movement.\xa0\nFor best results, preparation is completed in a step-down approach.\xa0\nAfter mechanical shaping of coronal and middle thirds with Gates-Glidden drill, insertion of the instrument is done with a quarter turn clockwise rotation while slight apical pressure is applied.\xa0\nCutting is accomplished by making a "Counterclockwise rotation".\xa0\nThe counter-clockwise rotation and apical pressure act together to enlarge and shape the canal to the diameter of the instrument.\xa0\nThe clockwise rotation should not exceed 90° while the counterclockwise motion must be 120° degrees or greater.', 'role': 'assistant'}]