**4. Characteristics of dentin and bone**

 Dentin and bone are mineralized tissues. Dentin is cell-free matrix without a blood vessel, while bone includes osteocytes and vessels. However, dentin and bone are almost the same in chemical components. They consist of biological apatite (HAp: 70%), collagen (18%), non-collagenous proteins (NCPs: 2%), and body fluid (10%) in weight volume (**Table 1**). BMPs and FGFs are matrix-binding proteins,



#### **Table 1.**

*Chemical components (wt/v%) of human dentine and bone.* 

**Figure 2.** 

*DDM and DBM. BMPs and FGFs, matrix-binding proteins in NCPs. Collagen, mainly type I collagen.* 

while OCN is a mineral-binding protein in NCPs [13]. The small integrin-binding ligand, N-linked glycoprotein (SIBLING) family, including dentin sialophosphoprotein (DSPP), dentin matrix protein 1 (DMP1), bone sialoprotein (BSP), and osteopontin (OPN), are secreted into the ECM during the biomineralization [23–26]. The SIBLING phosphoproteins (DSPP, DMP1, BSP, OPN) bind to titanium beads [27]. DDM and DBM are mainly type I collagen (95%); the remaining is made up of NCPs, including a small amount of growth factors. Briefly, DDM and DBM are acid-insoluble collagen-binding bone morphogenetic proteins (BMPs) [28–30] and fibroblast growth factors (FGFs) [31–34] (**Figure 2**).
