In the current study, we used an in vitro cell culture system to evaluate the biocompatibility of two implant materials with different surface topography. Our objective was to establish the osseointegration potential of MDIs versus an established regular implant. Disks prepared from the implant material were coated with gelatin to grow cells, and proliferation and osteogenic differentiation parameters were evaluated. Considering that the disks obtained from two different sources varied in diameter, we attached 5-mm silicon rings to the surface of both types of disks in order to standardize the culture area. The use of vacuum grease created a leak-proof culture well that enabled us to grow and treat cells for the required period of time. Also, it was possible to use a limited number of disks as the system was easy to clean, disinfect, and reuse.

As cells were grown on metallic surfaces, it was not possible to detect them using light microscopy. This is why we used florescence microscopy to examine the cells and their functional properties once the experiment was complete. Considering that we were unable to routinely examine the live cells on the disks during the culture period, we grew the same number of cells under identical conditions on a plastic cell culture dish enclosed by the same type of culture rings. These cells were evaluated daily using an inverted light microscope, and based on the cell density and the amount of mineral precipitation in this latter culture, we decided to terminate the experiments with the cells grown on the disks.

Two different cell lines were used in our in vitro system: C2C12 and MC3T3-E1 cells. Both of these cell lines were developed from mouse tissues. C2C12 cells are myogenic, but retain the potential to express osteogenic markers under appropriate signaling events.