Injectable ß-TCP/MCPM cement associated with mesoporous silica for bone regeneration: characterization and toxicity evaluation.

Calcium phosphate cement has been widely investigated as a bone graft substitute due to its excellent self-setting ability, biocompatibility, osteoconductivity and moldability. In addition, mesoporous materials have been studied as potential materials for application in medical devices due to their large surface area, which is capable of loading numerous biological molecules, besides being bioactive. In this study, bone ß-TCP-MCPM-based injectable cement with mesoporous silica particles was synthesized and characterized in terms of its mechanical properties, microstructure, porosity, injectability, in vitro bioactivity and degradability; together with toxicity effects in CHO-K1 cell culture. The results showed that the ß-TCP-MCPM cement is bioactive after soaking in simulated body fluid solution, and mesoporous silica particles provided better physicochemical properties compared with silica-free cement. Toxicity assays showed low CHO-K1 cell viability after treatment with more concentrated extracts (200 mg ml-1). However, this behavior did not compromise the reproductive capacity and did not promote significant DNA damage in those cells. In conclusion, the ß-TCP-MCPM cement associated with mesoporous silica might be considered as a potential bone substitute for the repair and regeneration of bone defects.

Nanostructured materials based on mesoporous silica and mesoporous silica/apatite as osteogenic growth peptide carriers.

The aim of this work was the preparation of inorganic mesoporous materials from silica, calcium phosphate and a nonionic surfactant and to evaluate the incorporation and release of different concentrations of osteogenic growth peptide (OGP) for application in bone regeneration. The adsorption and release of the labeled peptide with 5,6-carboxyfluorescein (OGP-CF) from the mesoporous matrix was monitored by fluorescence spectroscopy. The specific surface area was 880 and 484 m(2) g(-1) for pure silica (SiO) and silica/apatite (SiCaP), respectively; the area influenced the percentage of incorporation of the peptide. The release of OGP-CF from the materials in simulated body fluid (SBF) was dependent on the composition of the particles, the amount of incorporated peptide and the degradation of the material. The release of 50% of the peptide content occurred at around 4 and 30 h for SiCaP and SiO, respectively. In conclusion, the materials based on SiO and SiCaP showed in vitro bioactivity and degradation; thus, these materials should be considered as alternative biomaterials for bone regeneration.

Bacterial cellulose-hydroxyapatite nanocomposites for bone regeneration.

The aim of this study was to develop and to evaluate the biological properties of bacterial cellulose-hydroxyapatite (BC-HA) nanocomposite membranes for bone regeneration. Nanocomposites were prepared from bacterial cellulose membranes sequentially incubated in solutions of CaCl(2) followed by Na(2)HPO(4). BC-HA membranes were evaluated in noncritical bone defects in rat tibiae at 1, 4, and 16 weeks. Thermogravimetric analyses showed that the amount of the mineral phase was 40%-50% of the total weight. Spectroscopy, electronic microscopy/energy dispersive X-ray analyses, and X-ray diffraction showed formation of HA crystals on BC nanofibres. Low crystallinity HA crystals presented Ca/P a molar ratio of 1.5 (calcium-deficient HA), similar to physiological bone. Fourier transformed infrared spectroscopy analysis showed bands assigned to phosphate and carbonate ions. In vivo tests showed no inflammatory reaction after 1 week. After 4 weeks, defects were observed to be completely filled in by new bone tissue. The BC-HA membranes were effective for bone regeneration.

Fixation of autogenous bone grafts with ethyl-cyanoacrylate glue or titanium screws in the calvaria of rabbits.

This study compared the fixation of autogenous onlay bone grafts with cyanoacrylate glue (Super Bonder) and with titanium screws. Twenty rabbits underwent bilateral parietal ostectomies. Bone segments were fixed anteriorly to the resulting bone defect. In group I, the grafts were fixed with 4 mm long, 1.5 mm diameter screws; in group II, adhesive was used. The animals were killed after 5, 15, 30, 60 and 120 days. Histomorphometric analysis was used to quantify the maintenance of the graft area. Discrete areas of inflammatory reaction were seen in both groups after 5 days and for group II after 15 days. After 30 days, new bone formation was seen at the interface of the grafts. After 120 days, the graft was incorporated into the host bed in group I and partially incorporated in group II. There was a significant statistical difference regarding the mean graft areas between 15 and 120 days (p<0.001) and between fixation methods (p<0.002). Fixation with adhesive promoted a significantly greater area of bone graft than screw fixation, independent of time period. The adhesive was biocompatible, presented similar stability to the screw and maintained the bone area, although there was a delay in graft incorporation.