Effect of platelet-rich and platelet-poor plasma on 3D bone-to-implant contact: a preclinical micro-CT study

Effect of leukocyte and platelet-rich plasma on osseointegration after implant placement in mouse maxilla

Introduction

Osseointegration, the direct contact between an implant and bone, can be achieved by direct and/or indirect osteogenesis. Platelet-rich plasma accelerates tissue regeneration, wound healing, and osseointegration. This study aimed to analyze the effects of leukocyte and platelet-rich plasma (L-PRP) on direct and indirect osteogenesis after implant placement in a mouse maxilla.

Methods

Blood was collected from the tail vein of 4-8-week-old male ICR mice and L-PRP was obtained after double-spin cycle centrifugation. After the right upper first molars of 4-week-old ICR mice were extracted while under deep anesthesia, the alveolar sockets were prepared with a drill, and titanium implants blasted with hydroxyapatite/β-tricalcium phosphate were placed into the cavity filled with 1.5 μL of L-PRP. Samples were collected from the animals 3-28 days after implantation, and immunohistochemistry for osteopontin, Ki67 (cell proliferation marker), cathepsin-K (osteoclast marker), and osteonectin (osteoblast marker) was performed.

Results

Cell proliferation was significantly higher in the L-PRP group than in the control group on postoperative days 3 and 5. The activities of osteoclast-lineage cells and osteoblasts increased significantly on day 5 in the L-PRP group, indicating that L-PRP evoked an active cellular response. Indirect osteogenesis was significantly higher on days 7, 14, and 28, and the osseointegration rate was significantly higher on day 28 in the L-PRP group compared with the control group.

Conclusions

L-PRP enhances osseointegration by promoting mesenchymal cell proliferation, osteoclastic and osteoblastic activities, and indirect osteogenesis.

Platelet-rich plasma alone is unable to trigger contact osteogenesis on titanium implant surfaces

PURPOSE

Osseointegration consists of bidirectional bone formation around modified implant surfaces by contact osteogenesis and distance osteogenesis. This study tested whether contact osteogenesis on the surface of a modified titanium (Ti) implant is stimulated by cytokines in the blood.

METHODS

In the first two types of experiments, sandblasted, large-grit, acid-etched Ti implants and turned Ti tubes were inserted into rabbit tibiae. To exclude the influence of distance osteogenesis, the tubes were inserted into the tibiae, and implants were placed inside the tubes. In a third type of experiment, the implants and tubes were inserted into the rabbit tibiae, and platelet-rich plasma (PRP) or recombinant human bone morphogenetic protein-2 (rhBMP-2) was applied topically. Four weeks after implantation, undecalcified specimens were prepared for histomorphometry. Bone-to-implant contact (BIC) and bone area per tissue (BA) were measured, and the data were analysed using one-way ANOVA at a significance level of 0.05.

RESULTS

When the response of bone to Ti tubes with implants was compared to that without implants (first experiment), little bone formation was found inside the tubes. The mean BIC of implant specimens inside the tubes was 21.41 ± 13.81% in a second experiment that evaluated bone responses to implants with or without Ti tubes. This mean BIC value was significantly lower than that in the implant-only group (without tubes) (47.32 ± 12.09%, P = 0.030). The third experiment showed that rhBMP-2 significantly increased contact osteogenesis on the implant surface, whereas PRP had no effect (mean BIC: 66.53 ± 14.06% vs. 16.34 ± 15.98%, P = 0.004).

CONCLUSIONS

Platelet-rich plasma alone is unable to trigger contact osteogenesis on the modified titanium implant surface.