Preosteoblast cells adhesion and proliferation increase onto zirconium nitride coated titanium screws

Dental implants integration in the native surrounding maxillary or mandibular bone relies on a complex physiological process known as osseointegration. Endosseous implants have to be integrated in alveolar bone and need to be highly biocompatible, in order to avoid any local or systemic adverse reaction. To date, endosseous implants are mainly produced using metal titanium and, to a lesser extent, metal zirconia. Titanium has been used so far as main constituent of dental implants; recent studies highlighted a higher osseointegration potential of zirconium derivatives such as zirconia (zirconium dioxide), even if these new devices are more expensive than titanium ones. In this study chemical and morphological characteristics of titanium implants (endosseous screws) coated with zirconium nitride have been evaluated by SEM and EDX analysis, along with their in vitro bioactivity. SEM and EDX analysis confirmed that zirconium nitride completely covered titanium implant surface. Moreover, murine pre-osteoblasts (MC-3T3 cells) were seeded onto titanium and zirconium nitride coated screws, in order to evaluate their adhesion and proliferation. After 24 hours of incubation, SEM analysis highlighted a significantly higher number of cells adhering and spreading onto zirconium nitride coated surfaces. After 7 days, cells grown onto zirconium nitrite coated surface create a more complex and interconnected environment compared to uncoated ones. These data suggest that the proposed zirconium nitride coating of titanium implant surface could be a valuable alternative to the use of pure titanium devices, accounting for the growing market requests for metal-free restorations.