Guided bone regeneration using rhGDF-5- and rhBMP-2-coated natural bone mineral in rat calvarial defects.

OBJECTIVES: The aim of the present study was to assess the influence of either recombinant human growth and differentiation factor 5 (rhGDF-5)- or recombinant human bone morphogenetic protein 2 (rhBMP-2)-coated natural bone mineral (NBM) on guided bone regeneration in a rat calvarial defect model. MATERIAL AND METHODS: Two monocortical critical-size calvarial defects (diameter 6 mm, depth 1.5 mm) were prepared in a total of 90 rats each (n=180 defects) and randomly allocated to the following groups: (1) NBM+collagen membrane (BG), (2) rhBMP-2+NBM+BG, (3) rhGDF-5+NBM+BG, (4) autogenous bone (AB)+BG, or (5) untreated control (C). At 1, 2, 4, 8, 16, and 24 weeks, dissected blocks were processed for histological [e.g. area (mm(2)) of mineralized tissue (MT)] and immunohistochemical (osteocalcin - OC, angiogenesis - TG) analysis. RESULTS: At 2 weeks, both coated NBM groups exhibited the formation of a thin hard tissue bridge underneath the BG. All test groups revealed significantly higher mean MT values than the C group at 24 weeks. rhBMP-2+NBM+BG-treated defects revealed significantly higher mean MT values in comparison with the AB+BG (8 and 24 weeks), NBM+BG (2 and 4 weeks), and rhGDF-5+NBM+BG (2, 16, and 24 weeks) groups, respectively. Immunoreactions to either OC or TG were comparable in all test groups. CONCLUSION: It was concluded that (i) all treatment procedures investigated supported bone regeneration at 24 weeks and (ii) rhBMP-2 might have the potential to improve the outcome of healing, particularly during the early stages of healing.

Cytotoxicity and proinflammatory effects of titanium and zirconia particles.

BACKGROUND: To assess the effects of differently sized titanium (Ti) and zirconia (Zr) particles on (1) the metabolic activity of osteosarcoma-derived osteoblasts (SaOs-2) and human gingival fibroblasts (HGF) and (2) the cytokine expression of monocytes (THP-1) METHODS: Ti (60-80 nm and 100 nm) and Zr (2 µm and 75 µm) particles were incubated with SaOs-2, HGF, and THP-1 cells. At days 0, 2, 4, and 7 and 0, 1, 2, and 4 (THP-1), the mitochondrial activity was assessed and enzyme-linked immunosorbent assays were used to determine interleukin (IL)-1 beta and IL-6 concentrations of stimulated THP-1 at day 1. RESULTS: Ti60-80, Ti100, Zr2, and Zr75 particles were associated with gradual and significant within-group decreases in the viability of SaOs-2 and HGF cells. These effects were less pronounced in the Zr group. Similar to control cells, THP-1 did not reveal any significant increases in IL-1 beta and IL-6 concentrations. Viability of THP-1 was merely impaired in the presence of Ti100. CONCLUSIONS: Ti and Zr particles had a detrimental effect on the viability of SaOs-2 and HGF, but no proinflammatory effect on THP-1.

Influence of different air-abrasive powders on cell viability at biologically contaminated titanium dental implants surfaces.

Studies have indicated that oral biofilm formation at structured titanium surfaces interferes with cell adhesion and proliferation, and its removal by means of conventional treatment procedures may not be sufficient to render these surfaces biologically acceptable. Therefore, the aim of the study was to evaluate the influence of different air-abrasive powders on cell viability at biologically contaminated titanium dental implant surfaces. Intraoral splints were used to collect an in vivo biofilm on sandblasted and acid-etched titanium discs for 48 h. A single (1x) and repeated (2x) use of four different powders (amino acid glycine or sodium bicarbonate particles; range of mean particle size (d(v50)):20-75 microm) was applied at two distances (1 and 2 mm) and angles (30 degrees and 90 degrees) to the surfaces. Specimens (2x) were incubated with SaOs-2 cells for 7 days. Residual biofilm (RB) areas (%), and surface alterations (SEM) (1x and 2x), as well as SaOs-2 cell viability, expressed as mitochondrial cell activity (MA) (counts/second) (2x specimens), were assessed. Comparable mean RB areas were observed within and between groups after both 1x (RB: 0.0% +/- 0.0% to 5.7% +/- 5.7%) and 2x (RB: 0.0% +/- 0.0%) treatments. All surface treatments did not lead to MA (2x) values comparable to the sterile control group. However, sodium bicarbonate particles resulted in significantly higher MA (2x) values than amino acid glycine powders of different sizes. This was associated with pronounced alterations of the surface morphology (2x). Within the limits of the present study, it was concluded that SaOs-2 cell viability at biologically contaminated titanium surfaces was mainly influenced by the particle type of the powder.