Critical Questions Surrounding the Shot-Blasting Treatment of Titanium Dental Implants

This review addresses four controversial aspects of shot blasting in the surface treatment of titanium dental implants. Shot blasting, which involves the projection of abrasive particles onto the titanium surface, is widely used to achieve surface roughness that promotes osteoblastic activity and, consequently, high levels of osseointegration. The first issue examined is the effect of residual alumina particles that remain embedded in the titanium surface after blasting. It has been shown that these residues-typically not exceeding 8% of the surface-can actually enhance osseointegration and even exhibit mild bactericidal properties. The second issue concerns the use of titanium dioxide particles for blasting. Our findings indicate that due to its low abrasiveness, titanium dioxide produces minimal surface roughness and low surface energy, resulting in limited osteoblastic adhesion, inferior fatigue performance, and reduced osseointegration compared to alumina-blasted surfaces. The third topic focuses on the role of compressive residual stress induced by grit blasting. Residual stress contributes to increased surface hydrophilicity, enhancing osteoblast adhesion and mineralization, as evidenced by elevated alkaline phosphatase levels. Finally, the fourth issue involves the effect of acid etching following grit blasting. This treatment introduces microroughness superimposed on the macroroughness generated by grit blasting. In vivo studies demonstrate that grit blasting is the primary driver of osseointegration, while acid etching provides only a marginal improvement in bone-implant contact.