In the diabetes group, the expression of TNF-α was strongly positive in the gingival epithelial layer, granular layer and stratum spinosum cells, fibroblasts, vascular endothelial cells, osteoblasts, osteoclasts and the cytoplasm of bone marrow stromal cells, and was positively expressed in the gingival epithelial basal layer (Fig. 5). Here, TNF is linked to diabetes mellitus.