With no explanation, label text_A→text_B with either "not_related" or "related".
text_A: Ivan Lendl has won 94 singles titles.
text_B: Dental compomers are materials which are used in dentistry as restorative material .. restorative material. dental restorative materials. They were introduced in the early 1990s as a hybrid of two other dental materials  : dental composites and glass ionomer cement .. dental composites. dental composites. glass ionomer cement. glass ionomer cement. They are also known as polyacid-modified resin composites .. They are used for restorations in low stress -- bearing areas
not_related.