Methods: RBM surfaced implants with 3.5mm in diameter and 8.5mm in length were designated as control group and implants surface treated with various diameters of nanotubes (30nm, 70nm, 100nm) of the same shape and size were designated as experimental group. The implants were placed in rabbit femurs and maintained unloaded for 4 and 12 weeks. After this period, the animals were sacrificed and Micro-CT analysis, histomorphometric analyses (bone to implant contact; BIC, bone volume; BV) and removal torque test were performed.
Results: In micro CT analysis, the bone volume at 12 weeks were significantly higher than at 4 weeks (p<0.05). The results also showed that 70nm experimental group had the highest bone volume at 4 and 12 weeks. However, there was no statistically significant difference (p>0.05). In histomorphometric analyses, the BIC value and BV value measured within three consecutive macro threads(Macro BV) at 12 weeks showed significantly higher value than at 4 weeks (p<0.05). 70nm experimental group displayed the highest BIC and Macro BV values at 4 weeks whereas 30nm experimental group showed the highest BIC and BV result at 12 weeks. The results from removal torque test revealed that 70nm experimental group had the significantly higher RTV result compared to other groups at 4 weeks (p<0.05), showing similar pattern to the result from Micro CT, histomorphometric analyses in that 70nm experimental group showed the highest value at 4 weeks whereas 30nm experimental group showed the highest value at 12 weeks.
Conclusion: 30nm and 70nm TiO2 nanotubes may have positive effects on osteogenesis and osseointegration around implants depending on the time of healing.