Figure 3. Morphology and biomechanical properties of mineralized tissue by dental pulp cells on titanium. Scanning electron microscopic (SEM) images of days 14 (A,B,C), 28 (D,E,F), and 42 (G,H,I) mineralized tissue by dental pulp cells in 3 culture conditions. Tissue on the polystyrene (A,D,G) depicts accretion of fibrous and small globular (arrow) structures, and rounded cells (asterisk). Tissues on titanium (E,F,H,I) depict laminar structure with small globules (arrow) and rounded cells (asterisk) on the surface. The crack appearance is seen as an artifact due to tissue contraction. Fibrous structures embedded within the lamina (arrow) are seen in the tissue on titanium (I). Bar = 20 µm for all panels. (J) A representative elemental spectrum obtained from energy-dispersive spectroscopy (EDS) of day 42 mineralized tissue on the machined titanium. Ca: calcium. P: phosphorus. Ti: titanium. (K) Calcium-to-phosphorus molar ratio of mineralized tissue in the 3 different culture conditions. Data are shown as the mean ± SD (n = 3). (L,M) Biomechanical properties of the tissue cultured in 3 different culture conditions: polystyrene, machined titanium (machined Ti), or dual-acid-etched titanium (DAE Ti). Hardness (L) and elastic modulus (M) measured by 200 mN maximum load nano-indentation. Data are shown as the mean ± SD (n = 3).