Endodontic pathologies are inflammatory diseases that cause immunological changes in the pulp and periodontium. Inflammatory reactions caused by pulpal diseases and toothache in the periodontium cause changes in the content of gingival crevicular fluid (GCF). Molecular tests of teeth with irreversible pulpitis, apical periodontitis, and with root resorption have shown an increase in some inflammatory mediators in GCF. The main inflammatory mediators measured in GCF in tests; Interleukin 8 (IL-8), Substance P (SP), Matrix metalloproteinase 2,8,9 (MMP-2,8,9), Neurokinin A, Calcitonin gene-related peptide (CGRP) and Tumor necrosis factor-alpha (TNF- α). It is thought that these changes in the GCF content may help in the diagnosis of pulpal diseases, determining the severity and choosing the right treatment. In this section, the relationships between endodontic pathologies and inflammatory mediators contained in DOS are presented.