The objective of this study was to explore the impact of an IRAK-4 inhibitor on the RANK/RANKL pathways in the macrophages THP-1 and peripheral blood mononuclear cells (PBMC) obtained from patients with apical periodontitis when exposed to Enterococcus faecalis and its major virulence factor, the lipoteichoic acid (LTA). The gene discussed is IRAK4; the disease is periapical periodontitis.