Corrosion Resistance of Titanium Dental Implant Abutments: Comparative Analysis and Surface Characterization

Metals subjected to the oral environment are prone to corrosion over time and this can be harmful. Metallic restoration components such as dental subgingival implant abutments are exposed to pH changes and different ions while in contact with saliva. The aim of the study was to evaluate the corrosion resistance of titanium dental implant abutments and to compare and contrast the surface characteristics of these alloys before and after corrosion. The corrosion examination (E_corr, j_corr, OCP, polarization curve) of two implant abutments (TiDesign EV, Astra Tech, Dentsply, York, PA, USA; Individual Titanium Abutment, Apollo Implants Components, Pabianice, Poland) was performed in 0.9% NaCl and 5% HCl. Moreover, specimens were investigated using SEM-EDS before and after the corrosion test. The value of j_corr in NaCl was higher for Astra (34.2 × 10^-8 ± 2.5 × 10^-8 A/cm²) than for Apollo (8.8 × 10^-8 ± 2.5 × 10^-8 A/cm²). Whereas, in HCl, the opposite relationship was observed (Astra 2.9 × 10^-4 ± 0.8 × 10^-4 A/cm² and Apollo 62.7 × 10^-4 ± 9.3 × 10^-4 A/cm²). An average reactive anodic current density in NaCl for Astra amounted up to ~0.2 × 10^-5-1.5 × 10^-5 A/cm², while for Apollo-up to ~3.3-9.7 × 10^-7 A/cm². The composition of both alloys after corrosion in NaCl demonstrated some changes: a decrease in the Ti, and Al and an increase in oxygen content. Hence, both alloys after corrosion in HCl demonstrated some minor changes in the elemental composition. Based on the results it can be concluded that: 1. Astra and Apollo abutments revealed good corrosion resistance and a passivation layer on the surface. 2. Apollo abutments exhibited better corrosion resistance in a neutral environment, suggesting that Astra abutments were found to be more resistant to corrosion in an acidic medium.