1. Flow cytometric analysis of memory T cell subsets (TSCM, TCM, TEM, TTE, TRM) in periodontitis tissue as compared with healthy periodontal tissue
2. To investigate the expression profile of cytokines (IL-2, TNF-?, IFN-?, RANKL), granzyme B in different subsets of periodontal tissue memory T cells
3. To study anatomical localization of periodontal tissue TRM that express CD103 by immunohistochemistry