Influence of rhBMP-2 and rhBMP-7 in fibrin on osseointegration of SLA implants: a preclinical evaluation

This in vivo study investigated the effect of recombinant human bone morphogenetic proteins-2 and -7 (rhBMP-2 and rhBMP-7) in both contained and non-contained defects on the osseointegrative capacity of sandblasted, large-grit and acid-etched (SLA) titanium implants in a rabbit tibia model. 32 SLA titanium implants were divided into SLA, SLA-F (with fibrin matrix), SLA-F-rhBMP-2 and SLA-F-rhBMP-7 groups. Implants were inserted into the tibiae of eight rabbits, with four rabbits euthanized at 2 and 8 weeks (n = 4). Fluorescent bone labeling procedure was conducted for the rabbits that would be euthanized 8 weeks post-implant placement, injecting tetracycline, xylenol orange and calcein blue every 2 weeks. Histomorphometric analysis was used to measure the height of new bone, periodic bone formation (PBF), bone-to-implant contact (BIC) and bone area (BA) ratios. All data were analyzed using one-way ANOVA with Tukey's post hoc test at a significance level of 0.05. SLA-F-rhBMP-2 group exhibited significantly greater new bone formation compared to SLA-F group at 8 weeks at the supracrestal peri-implant region (P = 0.048). Conversely, all groups showed similar bone healing quality at the interface between the implants and the existing bone. No significant differences were found in the PBF, BIC or BA values. Within the limitations of this preclinical study, fibrin-delivered rhBMP-2 significantly increased bone formation in supracrestal peri-implant regions, which can be interpreted as non-contained defects. At the bone-implant interface, neither rhBMP-2 nor rhBMP-7 added benefit.