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': 'Type of cyst that contains an epithelial lined cavity that is open towards the  root canal of the aﬀected tooth is known as: \nSelect and explain. \nA. Periapical true cyst, B. Periapical pocket cyst, C. Periapical pseudocyst, D. Degenerative cyst', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Periapical pocket cyst:\n\nThe cyst contains an epithelial-lined cavity that is open towards the root canal of the aﬀected tooth.\xa0\nIt was originally designated as bay cyst and is now redesignated as the periapical pocket cyst.\nThe periapical pocket cyst is probably initiated by the accumulation of neutrophils around the apical foramen in response to microbial bioﬁlm present in the apical portion of the root canal.\xa0\nThis forms a\xa0microabscess that gets enclosed by the proliferating epithelium, forming a collar with epithelial attachment on contacting the root tip.\xa0\n\nTextbook of Endodontics Nisha GARG 3rd ED', 'role': 'assistant'}]