With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Brittany Murphy was a person.
text_B: The idea of a Tooth Worm is an erroneous theory of dental caries , periodontitis and toothache ætiology .. dental caries. dental caries. periodontitis. periodontitis. toothache. toothache. Once widespread , the belief is now obsolete , having been superseded by more scientific rationales .. It was supposed that the disease was caused by small worms resident within the tooth , and eating it away .
not_related.