Influence of novel sessile drop measurement techniques on the quantification of wettability on dental implant...

Scale-dependent wetting analyses requires sophisticated generation of drops with adequate, variable drop sizes. Advanced drop shape analysis systems enable the generation of drops from micro- to picoliter range. This study investigates the influence of different drop generation techniques and measurement settings on wetting results on differently modified titanium surfaces.

Different titanium surfaces, thoroughly characterized by SEM, roughness, and XPS analyses, were included in this study: machined (M), etched (A), grit-blasted (SL), grit-blasted and acid-etched (SLA). To quantify wetting behavior, water drops were generated by three techniques yielding micro, nano and pico drops, respectively. In total, the drop volume varied from 0.3 nL to 1000 nL and the number of droplets added to generate a final drop volume from 1 to 200 drops.

With smaller drop volumes, hydrophilicity increased on the A, SL and SLA surface. Furthermore, fewer droplets used to generate the same final volume resulted in increased hydrophilicity. In general, the drop volume has less impact than the droplet number. Additionally, the applied drop dispensing technique influences the contact angle results.

The study results suggest that multiscale topographies should be evaluated using multiscale wetting approaches. Since wetting analysis results depend on both surface properties and measurement conditions, such as drop application technique and size, careful interpretation of generated data is mandatory.