(1) TLR4/NF-κB signaling pathways in dental mesenchymal/epithelial cells in T1DM rats are activated, which results in the aggravation of proliferation and the apoptosis of those cells, as well as the inhibition of SMAD1/5/8 phosphorylation leading to decreased odontoblasts differentiation and dentin formation. This evidence concerns the gene SMAD1 and type 1 diabetes mellitus.