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': 'Given technique is called as: \nSelect and explain. \nA. Standardized technique, B. Balanced force technique, C. Stepback technique, D. Crown down technique', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Crown-Down Technique\nNumerous modifications of the original step-down technique have been introduced, including the description of the crown-down technique. The more typical step-down technique includes the use of a stainless steel K-file exploring the apical constriction and establishing working length.\xa0\nIn contrast, a crown-down technique relies more on coronal flaring and then determination of the working length later in the procedure.\nThe more typical crown-down, or double-flare\xa0technique consisted of an exploratory action with a small file, a crown-down portion with K-files of descending sizes, and an apical enlargement to size\xa0 #40\xa0 or similar.\xa0 The original technique included stepping back in 1-mm increments with ascending file sizes and frequent recapitulations with a small K-file and copious irrigation. It is further emphasized that significant wall contact should be avoided in the crown-down phase to reduce hydrostatic pressure and the possibility of blockage. Several studies demonstrated more centered preparations in teeth with curved root canals shaped with a modified double-flare technique and Flex-R files compared to shapes prepared with K-files and step-back technique.\xa0\nA double-flare technique was also suggested for ProFile rotary instruments.', 'role': 'assistant'}]