Fig. 2

Various reparative dentin was deposited on the wall of the root canal, impeding dye penetration into the infected dentin. (A) Tooth 36 (left mandibular first molar) with periapical lesions in a 23-year-old man. (A-1) Apical section of mesial root canal (black arrow in A) (×40). (A-2/3) Magnifications of the area of the root canal wall indicated by the box in (A-1) (×100 and ×200), showing the reparative dentin with disordered and curved tubules clearly demarcated from normal dentin, resembling mineralized fibrous scar tissue (yellow arrow). (B) Tooth 16 (right maxillary first molar) with periapical lesions in a 21-year-old woman. (B-1) Apical section of palatal root canal of tooth B (black arrow in B) (×40). (B-2/3) Progressive magnifications of the area of the root canal wall indicated by the box in (B-1) (×100 and ×200), showing osteodentin, presenting traces of cells in its bone-like structure and no tubules in its matrix (yellow arrow)