The Response of Osteoblast-Like SaOS-2 Cells to Modified Titanium Surfaces

Purpose: To study the effects of different chemically modified titanium surfaces on the proliferation, differentiation, adhesion, and apoptosis of osteoblast-like SaOS-2 cells. Materials and Methods: In this work, six different titanium materials were tested and compared to each other: (1) glazed; (2) unglazed; (3) unglazed and alkali-etched; (4) unglazed, sandblasted, acid- and alkali-etched; (5) unglazed and coated with zirconium nitride; and (6) unglazed, sandblasted, and acid-etched. The production of alkaline phosphatase (ALP), tumor necrosis factor alpha (TNF-α), matrix metalloproteinase-2, and the expression of adhesion proteins (integrin α3β1, vinculin) were evaluated using ELISA. Finally, the apoptosis of cells was analyzed by flow cytometry. Results: The most significant differences were found for unglazed sandblasted acid- and alkali-etched titanium discs compared with unglazed titanium discs. The production of TNF-α was decreased after 24 hours, as was the production of ALP after 72 hours. In contrast, the expression of integrin α3β1 was increased after 6 hours. None of the titanium discs showed an apoptotic effect on cells. Conclusions: This study has shown that physical surface treatments (such as surface roughness) play a more important role than chemical modifications. Generally, chemical modifications such as acid- and alkali-etching can affect the wettability of titanium surfaces, making a surface hydrophilic or hydrophobic according to the modification. The cell attachment is better on hydrophilic surfaces, while hydrophilic surfaces may slightly decrease the expression of ALP activity.