Immunological Profile of Periapical and Periodontal Lesions: Current Concepts in the Role of T Cells

Periapical lesions of endodontic origin and periodontitis are the two common chronic conditions that constitute the immunoinflammatory responses to putative oral pathogens. Both the conditions encompass similar patterns of development and pathologic mechanisms of host-mediated tissue destruction and subsequent establishment of the lesion. This host inflammatory response is attributed to a large array of immune cells that play a regulatory role in the protective and destructive pathways culminating in these two diseases. Hence, knowledge of the host response involved in their pathogenesis is essential to comprehend the disease process and thus aid in establishing proper therapeutic strategies to keep the host response under control. This review will focus on the pivotal role played by the T cells and its various subsets, namely the T helper (Th)1, Th2, Th17, Treg, Th22, and Th9, and elicit deeper insights on the Th1/Th2 and the Th17/Treg paradigm.