Residual-Free Micro-Nano Titanium Surfaces via Titanium Blasting and Single Acid-Etching: A Cleaner Alternative

Abstract

Background: Traditional sandblasted large-grit acid-etched (SLA) surface treatments frequently utilize alumina (Al₂O₃) blasting, which may leave residual particles embedded in implant surfaces, potentially compromising biocompatibility and osseointegration. This study investigates a contamination-free alternative: titanium dioxide particle (TiO₂) blasting followed by hydrochloric acid (HCl) etching, aimed at generating a cleaner, hierarchical micro-nano-textured surface.

Methods: Grade IV titanium disks were treated either with TiO₂ sandblasting alone or with an additional HCl etching step. Surfaces were analyzed via atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle measurements, and profilometry. hFOB osteoblasts were cultured to assess adhesion, proliferation, metabolic activity, and morphology.

Results: The combination treatment produced a more homogeneous micro-nano structure with significantly increased roughness and a cleaner surface chemistry. Osteoblast proliferation and metabolic activity were notably improved in the TiO₂ and HCl group. SEM imaging showed a more organized cytoskeletal structure and pronounced filopodia at 72 h.

Conclusions: Titanium blasting combined with HCl etching yields a cost-effective, contamination-free surface modification with promising early-stage cellular responses. This approach represents a safer and effective alternative to conventional SLA treatment.

Keywords: implant surface; in vitro study; micro and micro–nano surface; osteoblasts.

Figure 1

Representative image of the disks used: (left) surface treated with TiO₂ sandblasting; (right) surface treated with combined treatment TiO₂ and HCl.

Figure 2

Atomic force microscopy (AFM) of titanium surfaces used in the study: (a) surface treated with TiO₂ sandblasting; (b) surface treated with combined treatment TiO₂ and HCl.

Figure 3

Schematic representation of SEM inspection images illustrating horizontal and vertical surface morphology across different surface treatments at various magnifications (I) 1 K; (II) 6 K; (III) 6 K; (IV) 8 K. The horizontal view presents a top-down perspective of the disk surface, highlighting the overall distribution of surface features such as pores and microstructures. The vertical view shows a cross-sectional-like morphology that reveals the depth and contours of the surface irregularities, providing insight into the roughness and profile variation created by different surface treatments.

Figure 4

Schematic representation of the water contact angle of two surface treatment samples.

Figure 5

Cell viability represented as % in each group. Cell viability (%) of hFOB cells on TiO₂ sandblasting and TiO₂ and HCl-treated surfaces at 24 h and 72 h. A significant increase was observed over time in both groups, with higher viability in the acid-treated group at 72 h (p < 0.05). *: statistically significant difference (p < 0.05).

Figure 6

hFOB cell proliferation on TiO₂ sandblasting and TiO₂ and HCl surfaces at 24 h and 72 h. A time-dependent increase was observed, with the TiO₂ and HCl group exhibiting significantly enhanced proliferation at 72 h compared to TiO₂ sandblasting (p < 0.05). *: statistically significant difference (p < 0.05).

Figure 7

Metabolic activity of hFOB cells with different surface treatments, significant differences can be observed at day 3, favoring acid-enhanced groups. *: statistically significant difference (p < 0.05).

Figure 8

SEM cell morphology of disks during (a) 24 h and (b) 72 h, under different magnification (I) 1 K; (II) 3 K.

Figure 9

hFOB adhesion and cytoskeleton were evaluated on the surfaces after (a) 24 h and (b) 72 h, (I) FITC; (II) DAPI; (III) merged.