Abstract
This study was designed to identify lymphocytes and to compare the lymphocyte distribution in endoodontically treated periapical lesions with that in endodontically untreated periapical lesions by way of immunohistochemical staining. Twenty-one human dental periapical lesions were obtained, frozened, serially sectioned to $4-5{\mu}$, and stained using the three-stage indirect immunoperoxidase technique and monoclonal antibodies for detecting the presence of B,T lymphocyte and T suppressor cell. Following results were obtained; 1. All of the examined periapical lesions had positive staining for B,T lymphocyte and T suppressor cell. 2. The concentration of T lymphocytes in 18 lesions diagnosed as periapical cyst and granuloma in both groups was greater than that of B lymphocytes and 2 periapical lesions identified as abscess in treated lesions had more positive B lymphocytes than positive T lymphocytes. 3. The average numbers of T,B lymphocytes and T suppressor cells in Endodontically treated lesions were lower than those of untreated lesions, but no statistically significant difference was noted. 4. When the distribution ratios of T lymphocytes to B lymphocytes and T suppressor cells to T lymphocytes were compared in Endodontically treated lesions by the histological aspects of the lesions and at the intervals of the duration after Endodontic treatment, a statistically significant change was not found. 5. The mean values of T lymphocytes, B lymphocytes and T suppressor cells in Endodontically treated lesions were markedly decreased in the specimens obtained at 3 month after Endodontic treatment, but no statistically significant difference was found.