In 2019, the study by Teodorescu et al. [38] in a population of patients affected by aggressive and chronic periodontitis observed significantly greater values of RANKL and the RANKL/OPG ratio in the saliva of the periodontitis patients in comparison with the healthy group, although no differences were observed between the two periodontitis stages, even if they were positively associated with bleeding and probing. The gene discussed is TNFSF11; the disease is periodontitis.