In-Vitro Phenotypic Response of Human Osteoblasts to Different Degrees of Titanium Surface Roughness

Abstract: Objectives: This study aimed to investigate human osteoblast (HOB) responses towards
different degrees of titanium (Ti) implant surface roughness. Methods: Four degrees of Ti surface
roughness were investigated on a micrometer roughness scale: smooth (S: 0.08–0.1 m), minimally
rough (MM: 0.3–0.5 m), moderately rough (MR: 1.2–1.4 m), and rough (R: 3.3–3.7 m). HOB cells
were cultured, expanded, and maintained according to the supplier’s protocol. Cell proliferation
and cytotoxicity were assessed at day 1, 3, 5, and 10 using alamarBlue and lactate dehydrogenase
colorimetric assays. Data were analyzed with one-way ANOVA, two-way ANOVA, and Tukey’s post
hoc test (p = 0.05 for all tests). Results: There was no significant difference in the cell proliferation or
cytotoxicity of the HOB cells in contact with the different degrees of Ti surface roughness. There was,
however, a significant time effect on cell proliferation (p < 0.0001) with different exposure durations
for each roughness degree. Furthermore, a positive correlation (non-significant) between proliferation
and cytotoxicity was observed for all investigated degrees of surface roughness. Conclusion:
All investigated roughness degrees showed comparable HOB proliferation, with the MR surface
presenting the highest percentage, followed by the R, MM, ad S, surfaces, respectively. The S surface
showed the highest cytotoxic effect on HOBs; however, it did not reach the cytotoxic level suggested
by the ISO for any medical device to be considered cytotoxic.