Reconstruction of mandibular bone defects using biphasic calcium phosphate bone substitutes with simultaneous implant placement in mini-swine: A pilot in vivo study.

This study aimed to investigate implant osseointegration using a new strategy of biphasic calcium phosphate (BCP) bone substitutes with simultaneous implant placement in mandibular reconstruction. Additionally, the temporal transcriptional profile associated with the early biological processes during osseointegration was determined. BCP and hydroxyapatite (HA) bone substitutes with simultaneous implant placement were grafted into mandibular defects created in mini-swine. Radiographic, histological, and biochemical analyses were applied for evaluation of osseointegration effects at 4 months after the grafting procedure. Bone formation around the implant was assessed by the bone area percentage (BA%) and the bone-implant-contact percentage (BIC%). The biomechanical evaluation was performed by the implant pullout test and the removal torque test. Microarray technology was utilized for gene expression comparison analysis at day 14 postoperatively. Radiographic and histological observation indicated enhanced bone formation in the BCP group compared to the HA group. Histomorphometric analyses of BA% and BIC% as well as biochemical analyses of the maximal pull-out force and the ultimate shear strength were all significantly greater in the BCP group (p < 0.05). Transcriptional analysis at an early stage of osseointegration revealed that genes belonging to biological processes associated with cell proliferation, development, osteogenesis, angiogenesis, and neurogenesis as well as the osteogenesis-related TGF-β/BMP and WNT signaling pathways were upregulated in the BCP group. In conclusion, the reconstruction of mandibular defects using BCP with simultaneous implant placement resulted in superior osseointegration effects. A number of candidate genes that were differentially expressed may contribute to the superior osseointegration effects.