Considering the elevated TRAP+ osteoclasts and increased levels of periodontitis associated cytokines (e.g. TNF-α and IL-1β) in the PPDM group, one explanation for the similar severity of periodontal lesions between groups may be that the mice were euthanized 6 weeks after transplantation, and it might take more than 6 weeks for significant differences to appear. This evidence concerns the gene TNF and periodontitis.