It was found that, in human periodontitis biopsies, RANKL mRNA expression levels were increased, while OPG expression levels were decreased, thus reducing the OPG/RANKL ratio.25Therefore, PDLSCs-CM at 1 μg/mL may demonstrate the benefits in reducing bone destruction as indicated by an increased OPG/RANKL ratio. The gene discussed is TNFRSF11B; the disease is periodontitis.