Objective: Possible changes in the biological potential of titanium (Ti) over time have never been examined; it is assumed that the biological properties, particularly osseointegration capability, of titanium surfaces are stable. The objective of this study was to test the hypothesis that the protein adsorption capacity and cell attractiveness of Ti, which are critical to the process of osseointegration, change over time during its use.
Materials and methods: Ti disks with three different surface topographies were prepared: machined, acid-etched and sandblasted. Some disks were tested for biological capacity immediately after the processing and some after being stored under dark ambient conditions for 4 weeks. Protein adsorption capacity of Ti was examined using albumin and fibronectin. Cell attractiveness of titanium was evaluated by examining the number of rat bone marrow-derived osteoblasts attached to Ti disks.
Results: For all surface types, protein adsorption capacities of 4-week-old Ti disks were substantially lower than the matching fresh Ti disks (
e.
g., the amount of fibronectin adsorbed to 4-week-old acid-etched surfaces during 24 hours was approximately 50% of that on the freshly prepared acid-etched surfaces). The number of osteoblasts attached to 4-week-old acid etched surfaces was only 30% and 50%, respectively, at 6 hours and 24 hours of culture, of that seen on freshly prepared acid-etched surfaces. These biological phenomena were associated with the loss of superhydrophilicity on 4-week-old Ti surfaces.
Conclusions: The degrading trend of protein adsorption capacity and osteoblast attractiveness of Ti surfaces during 4 weeks of storage after processing was remarkable. This time-dependent biological degradation was demonstrated in three different Ti surfaces: acid-etched, machined and sandblasted surfaces. We suggest that this phenomenon requires immediate further study for possible substantial commercial, scientific and research impacts in the field.
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