Sinus Mucosa Thinning and Perforations after Sinus Lifting Performed with Different Xenografts: A Histological Analysis in Rabbits

Background: Experimental studies have shown a progressive thinning and perforations of the sinus mucosa associated with sharpened edges and the cutting projections of graft particles used simultaneously for maxillary sinus augmentation. Hence, the aim of the present study was to evaluate the damaging effects of two different bovine grafts on the sinus mucosa after sinus augmentation. Methods: Twenty New Zealand rabbits received a bilateral sinus lifting using, as fillers, two different types of deproteinized bovine bone in granules, one processed at low temperature (low-T group), and the other at high temperature (high-T group). Thinned mucosa sites (<40 µm) and perforations were evaluated in the sinus mucosa that were in contact with graft granules after 2 and 10 weeks, in ten animals per period. Results: After 2 weeks of healing, the number of thinned mucosa sites was 118 in the low-T group, and 149 in the high-T group (p = 0.191). At the 10-week assessment, the thinned sites increased to 237 and 195 sites, respectively. The numbers of sinus mucosa perforations after 2 weeks were eight and three in the low-T and high-T group, respectively. At the 10-week evaluation, the perforations increased to 19 in the low-T group, and to 14 in the high-T group. Conclusions: The contact with bovine xenografts yielded thinning and perforations of the sinus mucosa. Despite the differences in characteristics and dimensions, no differences were found between the two xenografts in the numbers of thinning mucosa sites and perforations. However, a trend of more events was found in the low-T compared to the high-T group.

Healing of Experimental Periodontal Defects Following Treatment with Fibroblast Growth Factor-2 and Deproteinized Bovine Bone Mineral

The aim of this study was to investigate the effects of fibroblast growth factor (FGF)-2 used in combination with deproteinized bovine bone mineral (DBBM) on the healing of experimental periodontal defects. Periodontal defects created in rats were treated by FGF-2, DBBM, FGF-2 + DBBM, or left unfilled. Microcomputed tomography, histological, and immunohistochemical examinations were used to evaluate healing. In vitro cell viability/proliferation on DBBM with/without FGF-2 was assessed by WST-1. Cell behavior was analyzed using scanning electron and confocal laser scanning microscopy. Osteogenic differentiation was evaluated by staining with alkaline phosphatase and alizarin red. Bone volume fraction was significantly greater in FGF-2 and FGF-2 + DBBM groups than in other groups at 2 and 4 weeks postoperatively. In histological assessment, newly formed bone in FGF-2 and FGF-2 + DBBM groups appeared to be greater than other groups. Significantly greater levels of proliferating cell nuclear antigen-, vascular endothelial growth factor-, and osterix-positive cells were observed in FGF-2 and FGF-2 + DBBM groups compared to Unfilled group. In vitro, addition of FGF-2 to DBBM promoted cell viability/proliferation, attachment/spreading, and osteogenic differentiation. The combination therapy using FGF-2 and DBBM was similarly effective as FGF-2 alone in the healing of experimental periodontal defects. In certain bone defect configurations, the combined use of FGF-2 and DBBM may enhance healing via promotion of cell proliferation, angiogenesis, and osteogenic differentiation.

Application of Bone Morphogenetic Protein 7 Enhanced the Osteogenic Differentiation and Mineralization of Bone Marrow-Derived Stem Cells Cultured on Deproteinized Bovine Bone

The growth of bone morphogenetic protein 7 (BMP-7) has been applied for tissue regeneration due to its osteoinductive properties. The aim of this research is to analyze the enhancing effects of BMP-7 on the osteogenic differentiation and mineralization of human bone marrow-derived stem cells cultured on the bovine bone particle. After the stem cells were loaded onto the bone graft material, their morphology was observed on day 7. Viability assays based on the application of fluorescent stains were used for qualitative analyses. Alkaline phosphatase activity assays and Alizarin red staining were used for the assessment of osteogenic differentiation on days 7 and 14. Next-generation mRNA sequencing was applied to evaluate global gene expression. Gene ontology and pathway analysis was used to propose the underlying mechanism. Fibroblast-like morphology was attained with the stem cells. The cells were shown to be firmly attached to the bone particle. Most of the stem cells produced an intense green fluorescence. The relative cellular viability assay values for BMP-7 groups at 0, 10, and 100 ng/mL on day 7 were 0.295 ± 0.003, 0.250 ± 0.002, and 0.240 ± 0.003, respectively (p < 0.05). Alkaline phosphatase activity was significantly higher in BMP-7 groups at concentration of 100 ng/mL compared to the control on days 7 and 14 (p < 0.05). The results of the mineralization assay showed significantly higher values for BMP-7 groups at 100 ng/mL concentration when compared with the control (p < 0.05). The expression of RUNX2 was increased with application of BMP-7 and mitogen-activated protein kinase pathway was associated with the target genes. Overall, this study shows that in vitro application of BMP-7 increases alkaline phosphorylase activity and mineralization of stem cells culture on deproteinized bovine bone mineral. The study suggests that combining stem cells with osteoinductive growth factors with scaffolds can have synergy effects on osteogenic differentiation.