SLA Surface Formation on Titanium-Based Dental Implant Materials: A Comparative Study of TiZr, cpTi, and TC4

Aims Surface characteristics play an important role in early osseointegration and implant stability. This study compared the surface morphology, 3-dimensional topography, elemental composition, phase characteristics, residual stress, and microhardness of titanium–zirconium alloy (TiZr), commercially pure titanium (cpTi), and Ti–6Al–4V alloy (TC4). Four surface conditions were evaluated: machined (M), sandblasted (SB), acid-etched (AE), and sandblasted, large-grit, acid-etched (SLA). We further evaluated whether the final SLA surface characteristics were consistent with a sequence-dependent mechanical–chemical surface evolution process. The study aimed to clarify material-dependent responses to SLA treatment and provide an experimental basis for matching implant materials with surface-treatment strategies. Methods A 3 × 4 factorial design was used. TiZr, cpTi, and TC4 specimens received M, SB, AE, or SLA treatment. Scanning electron microscopy (SEM) and 3-dimensional profilometry were used to characterize surface morphology. Three-dimensional profilometry was also used to measure arithmetical mean height (Sa) and developed interfacial area ratio (Sdr). Energy-dispersive X-ray spectroscopy (EDS) was used to assess elemental composition. X-ray diffraction (XRD) and sin²ψ analysis were used to evaluate phase characteristics and residual stress, respectively. Surface microhardness was measured using Vickers microhardness testing. Two-way analysis of variance (ANOVA) was used to evaluate the effects of surface treatment, material, and their interaction. Results All 3 materials showed similar treatment-dependent trends. SLA produced hierarchical surfaces that combined the rough framework created by sandblasting with micro-/submicrometer-scale pores. These surfaces were distinct from those produced by SB or AE alone. The SLA groups had the highest Sa (1.475-1.849 μm) and Sdr (6.736%-9.113%) values ( p < .001). After acid etching of the sandblasted surfaces, EDS signals attributable to residual aluminum oxide (Al₂O₃) were below the detection limit. All specimens showed compressive residual stress. The SB groups showed the greatest compressive stress, whereas the SLA groups retained moderate stress except for TC4. Microhardness followed the order SB > SLA > AE > M in all 3 materials. Surface treatment was the dominant factor and accounted for 76.7%–97.0% of the total variation. Conclusion SLA treatment produced hierarchical surfaces by retaining the large-scale topography created by sandblasting and introducing finer-scale features through subsequent acid etching. The findings are consistent with a sequence-dependent surface formation process. Although the magnitude of the responses varied among TiZr, cpTi, and TC4, the overall treatment-dependent patterns were similar across the 3 materials. Clinical Relevance The consistent surface responses of TiZr, cpTi, and TC4 to SLA treatment support their suitability for SLA-treated dental implants. These findings provide practical guidance for selecting titanium-based implant materials in different clinical indications, including narrow-diameter implant applications, immediate loading protocols, and cases with compromised bone quality.