TNF-a production to increase disease progression is triggered by endotoxins.31The role of TNF-a expression on bone resorption and exacerbation is established in apical periodontitis.21TNF-a is a potent inducer of bone resorption among other cytokines in apical periodontitis.32TNF-a interferes with autophagy and modulates pro-inflammatory responses, cell differentiation, proliferation, and death.31TNF-a expression is correlated with the amount of macrophages in the surrounding tissues, indicating the production of this cytokine and inflammation status.18 This evidence concerns the gene TNF and periapical periodontitis.