TNF and periapical periodontitis: IL-6 is synthesized at low levels in healthy periapical tissues but might be drastically upregulated during periapical inflammation.25High expression of IL-6 in apical periodontitis is correlated with active symptomatic lesions, but the relation to systemic inflammatory condition showed conflicting results.18IL-6 is a key cytokine expressed and released by several inflammatory cells, including macrophages, associated with bone resorption and host defenses.26Higher IL-6 level is positively associated with the size of the lesion, while higher TNF-a level is associated with exudation.27