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Poor bone quality and quantity are often related to implant failure. Synthetic bone grafts may be used to enhance the formation of new bone in bone defects. The purpose of this animal study was to determine the efficacy of bioactive glass particles of narrow size range (300 to 335 µm, Biogran) in the treatment of bone defects prior to implant placement. On both sides of the mandible of six beagle dogs, areas of partial edentulousness were created by the removal of the intra-alveolar septa to obtain large defects, instantly filled on one side with bioactive glass particles. The other side was left empty as a control. After a healing period of 4 months, three oral implants each were placed in the glass-treated area and in the control zone. In three dogs, the implants were left subgingival for 3 months after which histologic sections were made. In the remaining three dogs, the implants were functionally loaded with a fixed partial prosthesis for 7 weeks before sacrifice. Qualitative and quantitative analysis of both groups revealed statistically significantly more bone tissue and higher remodeling activity at the interface and at a distance of implants placed in glass-treated areas, compared to implants placed in untreated regions. Implant placement in bioactive glass-filled defects was not jeopardized, on the contrary. [ABSTRACT FROM AUTHOR]

This article reports a novel, simple route for synthesis of sol-gel derived porous, bioactive glass ( BG) microspheres using chitosan ( CTS) as a biomolecular template in the acid-catalyzed sol-gel process. The use of CTS, which is a natural biocompatible polymer with a unique molecular structure, allowed the synthesis of BG microparticles with a spherical shape, 5-10 μm in size. Furthermore, pores with a size of 5-40 nm were created entirely throughout BG microspheres, which were formed by removing the network of CTS present initially in the CTS-BG composite microparticles via heat-treatment at 600°C for 2 h. These porous BG microspheres induced the vigorous precipitation of apatite crystals on their surface when immersed in simulated body fluid for 24 h, thus suggesting their excellent bioactivity . [ABSTRACT FROM AUTHOR]

Bioresorbable calcium phosphate-polymer composite implants are a desirable alternative to the traditional metal bone-healing devices. Incorporation of antimicrobial drugs into the composite material and their sustained delivery may dramatically reduce the risk of implant infections. The paper reports the fabrication of drug-incorporated bioresorbable CaP-polymer nanocomposites that can be used for fracture fixation devices and at the same time function as local delivery systems. Vancomycin was incorporated into β-tricalcium phosphate (β-TCP)- and biphasic CaP (BCP)-based composites containing ≤30 vol.% polycaprolactone (PCL) or polylactic acid (PLA), during their high pressure consolidation at 2.5 GPa and room temperature. The antibiotic release was studied in Tris buffer solution at 37 °C. Up to 5 wt% vancomycin could be included without compromising material's integrity upon immersion into Tris solution. Vancomycin release profile was found to depend on the specific surface area of the test specimens and on the composite porosity. β-TCP-30 vol.% PLA composites were found to have the best combination of compression strength and drug release pattern. Complete drug release was accompanied by only negligible material dissolution suggesting a diffusion mechanism of release. In the context of bone-healing applications, such a release-dissolution pattern will allow local prophylaxis against implant-related infection at the early stages after implantation followed by a much more slow dissolution of the load-carrying device. [ABSTRACT FROM AUTHOR]

The main objective of this paper was to investigate the effect of transmission of force on bone cells that were attached to a deformable membrane. We functionalized a silastic membrane that measured 0.005 inches thickness and coated it with an extra cellular matrix (ECM) protein, fibronectin (FN). MC3T3-E1 osteoblast-like cells were cultured on the functionalized FN-coated membrane after which cell attachment and proliferation were evaluated.We observed an immediate attachment and proliferation of the bone cells on the functionalized membrane coated with FN, after 24 hours. Upon application of a mechanical force to cells cultured on the functionalized silicone membrane in the form of a dynamic equibiaxial strain, 2% magnitude; at 1-Hz frequency for 2 h, the osteoblast cells elicited slightly elevated phalloid in fluorescence, suggesting that there was reorganization of the cytoskeleton.We concluded from this preliminary data obtained that the engineered surface transduced applied mechanical forces directly to the adherent osteoblast cells via integrin binding tripeptide receptors, present in the FN molecules, resulting in the enhanced cellular attachment and proliferation. [ABSTRACT FROM AUTHOR]

Bioactive glass (BG) is an effective synthetic bone graft material. BG granules of narrow size range (300-355 µm) have the ability to form new bone tissue inside excavations produced by in vivo resorption. Previously, we demonstrated that BG stimulates the differentiation of cultured osteoblast precursors if the glass surface was biomimetically modified by the formation of bone-like apatite and adsorption of serum proteins. We now report that modified BG can also increase the rate at which multipotential rat bone marrow stromal cells (rMSC) will undergo osteogenesis. BG promoted rMSC osteogenesis both when cells were plated in contact with BG and when cells were not directly in contact with the BG. Alkaline phosphatase activity, a marker of bone cell differentiation, was used as an indicator for osteogenesis. Alkaline phosphatase activity of rMSCs exposed to osteoinducers such as ascorbate, dexamethasone, and BMP-2 was enhanced in the presence of BG. The stimulatory effect of BG was more pronounced in rMSC cultures with low basal alkaline phosphatase activity than in those with higher activity. The enhanced differentiation of rMSCs was associated with both a change in rMSC morphology and altered chemical composition of the cell culture media. rMSCs cultured on BG in the presence of BMP or dexamethasone exhibited a more rounded osteoblast-like appearance as compared with cells grown on tissue culture plastic. In the presence of BG, elevated levels of calcium and silicon in the culture medium were observed throughout the 7-day culture period, suggesting a continuous dissolution of surfacemodified BG and resulting release of BG dissolution products. The data suggest that both surface- and solutionmediated events play a role in the osteogenic effect of BG. [ABSTRACT FROM AUTHOR]

Previous studies demonstrated the capacity of bioactive glass particles of narrow size range (300–355 μm, Biogran®) to stimulate bone tissue formation without contact with pre-existing bone tissue. Chemical interactions between the bioactive glass and the surrounding tissue fluids caused the glass transformation. This study quantifies the time-dependent transformation process. Particles were implanted in the jaws of beagle dogs and resected after 1, 2, 3, 6, 12 and 24 months. Microchemical analysis was performed using a scanning electron microscope equipped with an energy dispersive X-ray analysis system. After one month, Na-ions were leached out and the particles transformed into two layers. In the center, a Si-rich gel was found on the outer surface, a Ca- and P-rich shell. After two months, the concentration levels of the outer Ca- and P-rich shell remained. In the center the Si-concentration decreased and the Ca and P concentration increased. After three months, Si disappeared completely from the center of the particle, while the Ca and P concentration increased. At one and two years, the Ca and P concentrations in the transformed particles equalled those of bone tissue, turning the transformed particle into a chemical equivalent of the bone mineral phase. [ABSTRACT FROM AUTHOR]

All non-noble metals and alloys will release metallic species into the body. This raises the issue of amount and fate, i.e. transport and storage, of these metal dissolution products. For titanium, the nature and extent of these systemic effects remain mostly unknown. In this study we investigated titanium levels in alleged target tissues in rabbits, both with and without a titanium implant functioning in the absence of wear, and compare these results to the limited body of literature concerning systemic levels of titanium. Titanium fibre felts were implanted into the tibia of rabbits. At various time points, lung, spleen, and muscle samples were collected from these rabbits as well as two groups of control rabbits. The samples were analysed for titanium concentration using electrothermal atomic absorption spectrophotometry. The data for the implant groups show that titanium levels in these tissues do not increase in comparison with controls up to 1 y after implantation. [ABSTRACT FROM AUTHOR]

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An alternative skeletal fixation by bone ingrowth into porous coatings has been studied. Stainless steel fiber coatings using different fiber diameters (50-100 μm) and different pore sizes have been tested. Plugs, intramedullary rods and various types of knee prostheses have been implanted in dogs in non functional and also in functional loading conditions. Histological and mechanical evaluation of the bone implant interface has been performed. Consistent bone ingrowth was observed for implants in non functional conditions if the pore size exceeded 70 μm. Ingrowth in functional loading conditions requires rigid initial stability of the implant and intimate contact of implantcoating and surrounding bone tissue. [ABSTRACT FROM AUTHOR]

Bioglass specimens were implanted in 11 dogs for periods ranging between two and twelve weeks in order to study the short term bonding behaviour of bioglass coated on metal. Metal fibre porous coated specimens without bone growth inducive microlayer were implanted as controls. The conclusions reached pertain to the validity of push out test results, bioglass short term bonding and the effect of the dipping procedure to coat bioglass on metal: [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate bone growth around bioactive glass particles in bone defects in comparison to hydroxylapatite particles. The bioactive glass particles were implanted in the partial edentulous jaws of Beagle dogs in two different compositions and several sizes and size ranges. After 1, 2, 3, 6, 12 and 24 months the samples were harvested and processed for undecalcified sectioning. Histological analysis showed a superior response of the bioactive glass particles of composition A and narrow size range (300-355 μm). Besides extensive osteoconductive properties, the bone repair was also stimulated by bone growth in the internally eroded particles. The data demonstrate conclusively that the well known corrosion reactions of the bioactive glass lead to the formation of protective pouches. In these protective pouches formation of new bone is detected without this bone being connected to the bone tissue outside the particles. These islands of newly formed bone tissue function as nuclei for further bone growth and enhance the repair of the defect. [ABSTRACT FROM AUTHOR]

Calcium-phosphate ceramic particulates are often used as filler material for enhanced repair of dental bone defects. Although evidence of bone ingrowth in the scaffold of these particles has been described, it is not observed consistently. Fibrous tissue often encapsulates these particles, which can subsequently become dispersed into the surrounding tissues or even exfoliated. The aim of the present study was to evaluate bioactive glass granules (Biogran™)* as a filler for osseous lesions, and to compare them with two commercially available Hydroxylapatite (HA) granules. The particulates were implanted in the jaws of five beagle dogs, resected and evaluated after 1, 2, 3, 6 and 12 months of implantation. Histological analysis revealed an improvement in repair of all the lesions. A massive osteoconductive bone growth was seen near the walls of the bony cavities, but in greater amounts around the bioactive glass granules than around the HA materials. On top of this massive growth a trabecular bone growth was observed in the centre of the bony cavities. These trabeculae were associated with the glass particles, which exhibited osteophilic properties, while fibrous tissue separated the bone tissue from the HA particles. The centres of many of the particles are excavated, and are subsequently filled by newly formed bone tissue. This internally formed bone tissue is not necessarily connected to the surrounding bone tissue, and functions as a nucleation site for further bone repair. For the mesenchymal cells within the eroded glass particles this inner environment acts as a stimulus to differentiate into osteoblasts and to start their osteogenetic potential. This phenomenon was not observed around the HA materials. If the latter were surrounded by fibrous tissue, disintegration of the surface by giant cells was observed. [ABSTRACT FROM AUTHOR]

Bioactive glass has the ability to bond with bone, but it cannot be used as a load bearing device due to its limited mechanical properties. By reinforcing bioactive glass with a ductile second phase, a structurally reliable material is obtained. The aim of the present study was to evaluate histologically and morphometrically the interfacial behaviour of submerged composite dental root implants. Therefore, bulk land composite implants were subgingivally installed in the partially edentulous jaws of Beagle dogs and harvested after 4 and 16 months. Histologically, the connection between the implants and bone tissue could be clearly demonstrated. This bone connection is mainly located at the cortical bone level. In the vicinity of the infraaveolar nerve a fibrous tissue contact was found. It is shown that surgical trauma, motion at the glass to tissue interface, and gross ion dissolution from the material adversely affect the interfacial osteogenesis. If these factors are controlled, bone bonding is found over a larger area than the initial area of contact between the implant and bone tissue. This means that bone grows out along the implant surface, starting from the initial contact area. No difference was observed between the interfacial behaviour of bulk bioactive glass and intact fibre reinforced bioactive glass implants. [ABSTRACT FROM AUTHOR]