Effects Of Storage Medium And UV Irradiation On Acid Etched Titanium Implant Surface

Rapid and firm establishment of bone-titanium integration mainly depends on the titanium implant surface characteristics and bioactivity. A series of recent studies reported titanium surfaces undergo a progressive change in their biologic characteristics after processing, resulting in a significant decrease in cell attachment, proliferation, differentiation and osseointegration capability, which was defined as the biological aging of titanium. The objective of this study was to investigate the combined effects of storage medium and UV irradiation on acid etched titanium implant surface characteristics and bioactivity.Firstly, titanium disc were sandblasted and acid etched, cleaned ultrasonically in dH2O and dried by nitrogen airflow (SLAnew), and stored in air (SLAold) or dH2O (modSLA) in a sterile environment for4weeks. Then, the4-week-old pecimens were irradiated by UV under ambient conditions using a15W bactericidal lamp for24hours (UV-SLA, UV-modSLA). The surface characteristics of the five group samples (SLAnew, SLAold, modSLA, UV-SLA, UV-modSLA) were detected. Spontaneously formed nanostructures were observed on water-stored surfaces (modSLA,UV-modSLA) with a size of about15nm in diameter. From XPS measurements, the carbon level showed varying degrees of rise for SLA old and modSLA than for those freshly prepared samples. However, when the samples stored for4weeks after processing were irradiated by UV, the carbon level dropped down and meanwhile increase Ti-OH groups. Except the group of SLAold, all the samples exhibited superhydrophilic. MC3T3-E1cells were cultured on the five group sample surfaces to detect the cell attachment, proliferation and differentiation. Compared with SLAnew, the cellular reponse of SLAold droped down significantly, while there was no statistical differences between modSLA and SLAnew. After UV treatment, the cellular reponse on UV-SLA and UV-modSLA increased, and showed even better bioactivity than SLAnew. UV-modSLA exhibited the greatest capacity of cell attachment, proliferation and ALP and OC expression.Besides, a total of160implants (32for each group) were inserted into the tibial metaphyses and femoral condyles of40rabbits. After3and6weeks, the rabbits were euthanized for removal torque tests and histomorphometric analysis. UV irradiated implants exhibited higher bone-implant contact (BIC) and bone area (BA), and UV-modSLA implants showed the highest removal torque value (RTV)In conclusion, this study investigated the surface characteristics and biocompatibility of freshly prepared SLA surfaces and SLA surfaces stored in air or dH2O for4weeks and then with or without UV treatment. Spontaneously formed nanostructures were observed on water-stored surfaces and UV irradiation could effectively eliminate the biological aging accompanied hydrocarbons contamination either titanium implant stored in air or water. UV photofunctionalization was effective in further enhancing the already increased bioactivity by using dH2O as storage medium, and the effect of UV treatment was much more overwhelming than storage medium. This study provids a unique way for the development of new generation titanium implants.