Improved osseointegration of long-term stored SLA implant by hydrothermal sterilization

The sandblasted, large-grit and acid-etched (SLA) surface is easy to be contaminated during storage and its surface chemical state is usually changed by different sterilization methods. This causes an undesirable increase in surface hydrophobicity and results in osseointegration degradation. To overcome this problem, a low temperature hydrothermal (HT) sterilization method was proposed in this study. Briefly, 4 weeks-stored pure titanium SLA specimens were sterilized using a sealed glass bottle with pure water in an autoclave set at 121 °C for 20 min. Results showed that, stored SLA specimens were superhydrophobic before and after conventional autoclaving, whereas, HT sterilization decontaminated and endowed stored SLA surface with superhydrophilicity. Osteoblast spreading was greatly enhanced, ALP expression was upgraded and bone nodule formation was obviously promoted on HT sterilized specimens compared with autoclaved ones. More bone formation around HT sterilized specimens was observed and HT sterilization increased bonding strength of implant to bone by 95% and 127% after 2 and 4 weeks of healing, respectively. The simple, feasible HT sterilization restored osseointegration of SLA implant while diminishing recontamination as much as possible. Therefore, it is proposed as a standard sterilization method for implant practitioners and researches.