TNFRSF11A and periodontitis: The host immune response to the presence of periodontopathogenic microorganisms activates several cytokine systems involved in alveolar bone resorption in periodontitis; among them is the receptor activator of nuclear factor‐κB (RANK)/receptor activator of nuclear factor‐κB ligand (RANKL) system, which depends on the interleukin (IL)‐23/IL‐17 axis.