AIM:To observe the expression of TLR2 and TLR4 on mast cells( MCs) in the periapical tissues from different types of human chronic periapical diseases,and to analyze the role of TLR2 and TLR4 on tryptase-positive MCs in the immunopathogenesis of human chronic periapical diseases.METHODS:A total of 60 donors,including healthy control group,periapical granuloma group and periapical cyst group,were enrolled in the study.The periapical tissue specimens were fixed in 10% buffered formalin and stained with hemato...