Unalloyed titanium, often referred to as commercially pure grade 4 titanium (CpTi), usually contains some trace elements of carbon, oxygen, nitrogen and iron (American Society for Testing and Materials international standards). These trace elements improve the mechanical properties of CpTi and are found in higher amounts from grade 1 to 4 CpTi. Many dental implants are made from grade 4 (G4) CpTi, in order to improve its fatigue strength, and companies have also used grade 5 (G5) titanium alloys (Ti-6Al-4 V), which contains metals including vanadium and aluminum.

In the present study, standardised implantoplasty procedure was performed on both G4 (Straumann, model number 021.4512, bone-level implant diameter 4.1 mm, Regular CrossFit®, SLA® 12 mm Roxolid®) and G5 (Biohorizons, model number PBR50105, RBT 5.0 × 12 mm, 5.7 Platform) implants. Implant particles were released from both types of implants (Fig. 1). The smaller particle size generated from G5 implants is likely to be due to the G5 alloy having a higher hardness. Typical G5 alloy has a hardness of 36 (HRC, Rockwell C) compared to 23 (HRC, Rockwell C) of G4. Some TiO₂ spheres were detected. This is because when titanium implant surface is exposed to air, titanium oxide (TiO₂) film is formed on the implant surface. This layer (1.5–10 nm thickness) is formed due to the high affinity of Ti for oxygen. This in turn could contribute to a certain degree of resistance to corrosion of titanium implants. G5 implant particles contain vanadium (Fig. 2), and vanadium ions were released into simulated body fluid and DMEM following 10 days immersion (Fig. 3 and 4).