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 µm), minimally rough (MM: 0.3−0.5 µm), moderately rough (MR: 1.2−1.4 µm), and rough (R: 3.3−3.7 µm). 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.

Keywords: cell proliferation; cytotoxicity; human osteoblasts; surface roughness; titanium; titanium surface roughness.

Figure 1

Ti discs with different roughness degrees (S, MM, MR, and R).

Figure 2

Profilometer surface roughness assessment and analysis: (A) Ti S surface, (B) Ti MM surface, (C) Ti MR surface, (D) Ti R surface.

Figure 3

SEM images: (A) Ti S surface, (B) Ti MM surface, (C) Ti MR surface, (D) Ti R surface.

Figure 4

A bar chart demonstrating the M P% values at days 1, 3, 5, and 10 for HOBs. Error bars represent the SD.

Figure 5

A bar chart illustrating the M cytotoxicity percentage values at days 1, 3, 5, and 10 for HOBs. Error bars represent the SD.

Figure 6

Line plots showing positive but non-significant correlations between proliferation and cytotoxicity for all surfaces from day 3 to day 10 and a non-significant negative correlation at day 1.