Figure 14. Disintegrated gutta-percha as potential cause of endodontic failures. As clusters of fine particles (a), they induce intense circumscribed tissue reaction (TR) around the particles. The regular demarcated area in (a) is magnified in (b). Note that the fine particles of gutta-percha (* in c, GP in d) are surrounded by numerous mononuclear cells (MNC). Magnifications: (a) 30x, (b) 80x, (c) 200x, and (d) 750x. (From Nair, 2002.)