withspreadofrelatedtoxicproductsinto theapicalzone. Initially. the defense reaction eliminates noxious sub- stances that exit the canals. Wi th time. however. the host reaction becomes less effective with microbial invasion or spread of toxins into the apical area.Periapical granulomas may arise after quiescence of a periapical abscess or may develop as the initial peri- apical pathosis. These lesions arc not static and may transform into periapical cysts or may demonstrate acute exacerbations with abscess format ion .