A Keyence VK-X1000/1050 (Keyence Deutschland GmbH, Neu-Isenburg, Germany) confocal laser scanning microscopy (CLSM) with a Nikon CF IC EPI Plan 50X (NA: 0.5, NIKON, Osaka, Japan) objective was used for surface measurement. Sa as the amount of the height difference of each point compared to the arithmetic mean of the surface was evaluated with Multi File Analyzer software (2.1.3.89, Keyence Deutschland GmbH, Neu-Isenburg, Germany) according to ISO 25178-2:2012. Therefore, five different areas per samples were characterized five times each with an area of 100 µm × 100 µm each and filtered to receive the surface for roughness evaluation (S-Filter: 0.5 µm; F-Filter: 0.1 mm; Filter type: spline).
As values identified for Sa were not normally distributed across the samples of all materials analyzed in this study (Shapiro-Wilk test [30 (link)]: p < 0.05), medians and 25/75 percentiles were calculated, and statistical analyses were performed using the Kruskal–Wallis test [31 (link)] and post hoc analyses using the Dunn [32 (link)] post hoc test with Bonferroni [33 ] correction. To determine the strength of the effects, Cohen’s r [34 ,35 ] was calculated using the psychometrica platform. The general level of significance (α) was set to 0.05, and for interpretation, the Bonferroni-adjusted p-values were used.
As values identified for Sa were not normally distributed across the samples of all materials analyzed in this study (Shapiro-Wilk test [30 (link)]: p < 0.05), medians and 25/75 percentiles were calculated, and statistical analyses were performed using the Kruskal–Wallis test [31 (link)] and post hoc analyses using the Dunn [32 (link)] post hoc test with Bonferroni [33 ] correction. To determine the strength of the effects, Cohen’s r [34 ,35 ] was calculated using the psychometrica platform. The general level of significance (α) was set to 0.05, and for interpretation, the Bonferroni-adjusted p-values were used.