Different titanium surface treatment influences human mandibular osteoblast response

Background: Six titanium disks with six different surface treatments were examined: SS: smooth (polished) surface; TPS: plasma spray; C 100: sand blasting by aluminum oxide (Al2O3) empty set 100 mum and acid etching; C150: sand blasting by Al2O3 empty set 150 mum and acid etching; B60: sand blasting by zirconium oxide (ZrO2) empty set 60 mum and acid etching; and B 120: sand blasting by ZrO2 empty set 120 mum and acid etching. Methods: The surface characteristics were determined by scanning electron microscopy (SEM) observation and a roughness tester. Raman spectroscopy was used to determine the presence of residual substances on the samples. Cells were seeded onto the disk and after 24 hours, 6 days, and 12 days were observed under SEM and growth curves generated with a cell counter. Some samples were used to determine alkaline phosphatase activity (ALP), using a colorimetric assay. Results: SEM observation revealed drastic differences in surface microtopography, with a higher cell density on sand-blasted and acid-etched (SLA) samples than SS and TPS, and more regularly aligned cells on B60 and B120 surfaces than on the others. The growth curves showed a greater adhesion of cells on the etched/blasted surfaces compared to the SS and TPS surfaces. The number of cells increased on all the SLA samples, especially B60, throughout the experiment. At the same time, there was considerable ALP activity on the B60 sample, while it remained at extremely low levels on SS and TPS surfaces. Raman analyses revealed Al2O3 debris on C100 and C150, partly explaining the poorer performances of these two surface treatments, since this substance was shown to be toxic for cultured osteoblasts. Conclusions: Surface treatments influence the growth and the metabolic activity of cultured osteoblasts, and B60 seems to be the most favorable surface inducing a more pronounced proliferation of cells together with a high differentiation degree.