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': "Which is not a non-radiographic methods of determining the working length: \nSelect and explain. \nA. Tactile sensation., B. Apical periodontal sensitivity., C. Paper point method., D. Bergman's Method.", 'role': 'user'}, {'content': 'Answer: D \nExplanation: NON-RADIOGRAPHIC METHODS\nTactile Sense\nIf the coronal portion of the canal is not constricted, an\xa0experienced clinician may detect an increase in resistance\xa0as the file approaches the apical 2-3 mm. This detection\xa0is by a tactile sense. it is ineffective in root canals with\xa0an immature apex and is highly inaccurate if the canal is\xa0constricted throughout its entire length of if it has excessive curvature. This method should be considered as a\xa0supplementary method. If the canals are not preflared,\xa0determination of the apical constriction by tactile sensation would be possible in only one-third of the cases\nApical Periodontal Sensitivity\nBased on the patients’, responses, dentists observe the ‘eye\xa0twitching’ sign. This is no more an acceptable method.\xa0Leads to too shorter determination of working length, in\xa0cases of inflamed tissues and overestimation in cases of\xa0non-vital teeth with periapical pathology\nPaper Point Method\nPaper points in the root canals with immature apex are\xa0the most reliable means determining the working\xa0lengths. This method is gently pass the blunt end of\xa0the paper point into the canal after profound anaesthesia is achieved. The moisture or blood on the portion\xa0of the paper point that passes beyond the apex may be\xa0an estimation of working length. This method cannot be\xa0used in weeping canals. This is a supplementary method.\xa0Paper points with millimetre marking have been introduced, recently.', 'role': 'assistant'}]