Alteration in the chemical composition of a biomaterial may be undertaken to improve its biological properties. The aim of this work was to evaluate the biocompatibility of three chemical compositions of Ricinus communis polyurethane (RCP): RCPp (pure RCP), RCP + CaCO(3), and RCP +Ca(3)(PO(4))(2). RCP cylinders were surgically implanted in rabbit femurs. After 8, 12, and 16 weeks, the femurs were removed, fixed, sectioned, ground, and stained by Stevenel's blue/Alizarin red S for light microscopy and histomorphometry. The osseointegration and osseoconductivity were calculated by means of image analysis and the data were submitted to the Kruskal-Wallis test followed by Dunn's test. Osseointegration was already completed after 8 weeks on RCP + Ca(3)(PO(4))(2) because similar values were found from week 8 to 16, whereas it showed a time-dependent increase on RCPp and RCP +CaCO(3). The osseointegration was greater on RCP + Ca(3)(PO(4))(2) in all periods when compared with RCPp, and after 8 and 12 weeks when compared with RCP + CaCO(3). None of the RCP samples presented osseoconductivity. The present results showed that RCP blended with calcium phosphate improved the biocompatibility by both enhancing and accelerating its osseointegration. Based on the absence of osseoconductivity, RCP was considered to be a bioinert material.

The aim of this study was to investigate the histological and histomorphometrical bone response to three Biosilicates with different crystal phases comparing them to Bioglass ® 45S5 implants used as control. Ceramic glass Biosilicate and Bioglass ® 45S5 implants were bilaterally inserted in rabbit femurs and harvested after 8 and 12 weeks. Histological examination did not revealed persistent inflammation or foreign body reaction at implantation sites. Bone and a layer of soft tissue were observed in close contact with the implant surfaces in the medullary canal. The connective tissue presented few elongated cells and collagen fibers located parallel to implant surface. Cortical portion after 8 weeks was the only area that demonstrated significant difference between all tested materials, with Biosilicate 1F and Biosilicate 2F presenting higher bone formation than Bioglass ® 45S5 and Biosilicate ® vitreo (p=0.02). All other areas and periods were statistically non-significant (p>0.05). In conclusion, all tested materials were considered biocompatible, demonstrating surface bone formation and a satisfactory behavior at biological environment.

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The aim of this study was to evaluate the bone response to three fluorcanasite glass-ceramic compositions with different solubilities (K3, K5, and K8) after implantation in a femur rabbit model. Fluorcanasite glass-ceramic rods were implanted bilaterally in the mid-shafts rabbit femurs. Implants were harvested at 8 and 12 weeks and prepared for histological and histomorphometric analyses at the light microscope level. Bioglass 45S5 rods were used as a control material. At 8 weeks, all fluorcanasite glass-ceramics were entirely surrounded by a nonmineralized connective tissue. At 12 weeks, reduced areas of bone tissue were observed in the cortical area in direct contact with the K3 and K5 fluorcanasite glass-ceramics compared to Bioglass 45S5, whereas no bone tissue was observed in direct contact with the K8 surface. Bone-to-implant contact in the cortical area was affected by the material chemical composition and ranked as follows: Bioglass 45S5>K3>K5>K8 (p=0.001). In the bone marrow, a layer of fibrous connective tissue formed in direct contact with the fluorcanasite glass-ceramics and Bioglass 45S5, and only rarely exhibited contact osteogenesis. All the fluorcanasite glass-ceramics appeared to degrade in the biological environment. The solubility ratio did not alter significantly the biological reply of the fluorcanasite glass-ceramics in vivo. Further modifications of the chemical composition of the fluorcanasite glass-ceramic are required to increase the stability of the material in vivo.