Purpose : To investigate the change of bone healing process after endodontic treatment of the tooth with an apical lesion by fractal analysis. Materials and Methods Radiographic images of 35 teeth from 33 patients taken on first diagnosis, 6 months, and 1 year after endodontic treatment were selected. Radiographic images were taken by JUPITER Computerized Dental X-ray $System^{(R)}$. Fractal dimensions were calculated three times at each area by Scion Image $PC^{(R)}$ program. Rectangular region of interest $(30 imes30)$ were selected at apical lesion and normal apex of each image. Results : The fractal dimension at apical lesion of first diagnosis $(L_0)$ is $0.940{pm}0.361$ and that of normal area $(N_0)$ is $1.186{pm}0.727(p<0.05)$. Fractal dimension at apical lesion of 6 months after endodontic treatment $(L_1)$ is $1.076{pm}0.069$ and that of normal area $ (N_1)$ is $1.192{pm}0.055(p<0.05)$. Fractal dimension at apical lesion of 1 year after endodontic treatment $(L_2)$ is $1.163{pm}0.074$ and that of normal area $(N_2)$ is $1.225{pm}0.079(p<0.05)$. After endodontic treatment, the fractal dimensions at each apical lesions depending on time showed statistically significant difference. And there are statistically significant different between normal area and apical lesion on first diagnosis, 6 months after, 1 year after. But the differences were grow smaller as time flows. Conclusion : The evaluation of the prognosis after the endodontic treatment of the apical lesion was estimated by bone regeneration in apical region. Fractal analysis was attempted to overcome the limit of subjective reading, and as a result the change of the bone during the healing process was able to be detected objectively and quantitatively.