To establish an evaluation model for peri-implant vasculature in the mouse femur in order to analyze spatio-temporal dynamics of vasculature around implants using a feasible and reliable method.

C57BL/6 mouse femurs were performed vascular perfusion with radiopaque agents and then scanned by Micro-CT with particular scanning and reconstruction parameters to image and quantify angiogenesis around implants in the distal ends. The left femurs were assigned to the perfusion experiment group with transcortical defects (Φ1 mm) for implant placement, while the right femurs were assigned to the negative control group without implant surgery. Mice were sacrificed on Day 1, 3, 7 and 14 post-surgery. Histological examination was performed simultaneously for comparison as the positive control group. The baseline was confirmed not significant by comparisons between varied timepoints within the negative control group. The vascular parameters in the perfusion experiment group were analyzed by using One-Way ANOVA and the Turkey′s test (P<0.05) .

We proposed a modified method by managing decalcified samples with implants pushed-out before Micro-CT scanning and setting up low-pass Gaussian filter σvalue and threshold. In contrast to the negative control group, there was significant difference between the peri-implant vasculature on Day 7 and the counterpart on Day 1 and Day 3 post-surgery. The peri-implant vasculature on Day 7 displayed higher vascular volume (F = 14.340, P_{1 d}<0.001, P_{3 d} = 0.001), vascular volume fraction (F = 16.230, P_{1 d}<0.001, P_{3 d}<0.001) and vessel thickness (F = 9.427, P_{1 d} = 0.006, P_{3 d} = 0.002) compared with those on Day 1 and 3. The number of vessel branches was also larger on Day 7 compared with that on Day 1 (F = 4.723, P_{1 d} = 0.019). Meanwhile, peri-implant vasculature decreased significantly from Day 7 to Day 14 with a reduction of 58% on the vascular volume fraction (F = 16.230, P = 0.006) and 35% on the average vessel thickness (F = 9.427, P = 0.041). The histological observation was in accordance with the outcomes above.

We proposed a feasible and low-cost Micro-CT modified method for observing and quantitating three-dimensional dynamics of angiogenesis around implant. The dynamic variation of peri-implant vasculature was observed, that is, the vasculature first increased together with vasodilated and then decreased. At its peak, the branch grew into collateral vessels around titanium implants within 7 days post-surgery.