TNFRSF11B and periodontitis: Tobón-Arroyave et al. [36] further explained their results by the fact that osteoclast differentiation regulation is based on the OPG expressed in the microenvironment surrounding osteoclast precursor cells [37]; thus, increased salivary OPG in CP patients might constitute a reflection of the actual biological activity of the basic multicellular unit within the periodontal ligament and alveolar bone and of the existing clinical periodontal status, thus indicating that a negative bone balance persists in periodontitis-affected tissues, which might also explain the findings presented herein.