This report examines three clinical cases of root-filled teeth with primary endodontic lesions. During endodontic surgery, an area of incomplete root bifurcation beginning in the coronal or middle third of the root surface and terminating at or near the apical foramen were observed. The radicular grooves of two teeth were eliminated using a round bur ("saucerization"), and the resulting defect was filled with a bone substitute or calcium sulfate and covered by an absorbable collagen membrane. The other tooth was extracted, the groove was eliminated with a similar technique, and the tooth was replanted. Bacteria have been reported in chronic epical lesions. Our observations suggest that after conventional endodontic therapy, the etiology of a nonresolving primary endodontic lesion may be bacteria of endodontic origin sequestered within the protective confines of an apical-radicular groove.