Effect of wet storage on the bioactivity of ultraviolet light- and non-thermal atmospheric pressure plasma-treated titanium and zirconia implant surfaces

The aim of this study was to evaluate whether combining two treatments to avoid biological aging of the surface of titanium and zirconia implants; ie., storage in an aqueous solution after ultraviolet light (UV) or non-thermal atmospheric pressure plasma (NTP) treatment, yielded surface bioactivity comparable to that following post-15-min UV or NTP treatment storage under air or immediately after UV or NTP treatment. Grade IV titanium discs modified by large grit sand-blasting and acid-etching (SLA) and smooth zirconia discs were irradiated with UV or NTP and their surface properties were evaluated immediately and after storage for 8 weeks in distilled H2O (dH(2)O) and a sealed container under air. Approximately 15-30 nm-sized nano-protrusions were formed only on SLA surfaces in dH(2)O immediately after UV or NTP treatment. Immediate dH(2)O storage after UV or NTP treatment prevented hydrocarbon contamination and maintained elevated amounts of Ti and Zr. After 8 weeks, unlike zirconia, protein adsorption, cellular adhesion, and cytoskeletal development of MC3T3-E1 cells on SLA surfaces stored in dH(2)O immediately after UV treatment were further exceeding those immediately after UV or NTP treatments. UV treatment of SLA implants followed by wet storage can not only maintain but also strengthen bioactivity during shelf storage.