After induction of experimental apical periodontitis, increased Osx-positive cells were not only located on the bone surface but also located within the broadened periodontal ligament area 2 weeks after induction (Fig. 6a1”, b) or within the apical periodontitis lesion 4 weeks after induction (Fig. 7a1”-1”’, b), which failed to form new bone at the bone resorption pit. The gene discussed is SP7; the disease is periapical periodontitis.