The junctional epithelium（JE） is the gingival portion of the dento- gingival tissue interface attached the tooth surface. Its unique location possesses a significant role in tissue homeostasis and defense against microorganisms and their products. Several studies have shown that the tissue structure, rapid renewing and immune response of JE play an active role in the periodontal defense response. The paper is to review the research progress in these fields so as to elucidate the pathogenesis of periodontitis.
