The loss of teeth is largely caused by supporting tissue damage, because of bacterial invasion from the infected root canals. Sixty patients with periapical lesions (PLs) of endodontic origin were included in the study. Clinical and radiological examination was performed. Periapical radiographs were analyzed by two independent observers to determine the size and severity of PLs, using Periapical Index (PAI) scores. The tissue samples collected by periapical curettage during apicoectomy or after dental extractions by alveolar curettage were histologically and immunohistochemically analyzed. The PLs were histologically diagnosed as: periapical granulomas (PGs), granulomas with cystic potential and radicular cysts (RCs) with various degrees of inflammation. Capillary density was evaluated using the angiogenic index after immunohistochemical staining with CD34 monoclonal antibody. A statistically significant correlation was observed between PAI scores and the size of the lesions. 68.33% of cases were PGs, 18.33% PGs with cystic potential and 18.33% RCs with different degrees of inflammation. Seventy-five percent PLs had an angiogenic index 1 and 25% had an angiogenic index 2. Statistically significant differences were obtained between the angiogenic index and lesion size (p<0.05). Capillary density within PLs did not influence the severity scores of lesions detected on radiographs. The angiogenic index appeared not to be associated with the histological lesion type and the intensity of inflammation, but was more likely correlated with the degree of granulation tissue maturation and the size of PLs.