IADR Abstract Archives
Characterization of a Novel Strontium Containing Bioactive Glass based Calcium Phosphate Cement
Objectives: The aim of this study was to investigate the effect of strontium and immersion media on crystal phase development and properties of a novel bioactive glass based calcium phosphate cement (CPC).
Methods: Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder and Ca(H2PO4)2 salt with a 2.5% solution of Na2HPO4. Samples were immersed in either 10 mL of Tris buffer solution or 10 mL of SBF for 1h, 1d, 7d and 28d. X- Ray Diffraction (XRD) was performed to assess phases formed after immersion. Compressive strength was measured after each time point and the fracture surfaces were studied under SEM. Cytotoxicity studies were performed using MC3T3-E1 osteoblasts. Cells were exposed to cement conditioned media and cell viability was assessed using an MTT assay.
Results: XRD showed that the amount of Sr2+ in the glass and the immersion media used influenced phases formed and mechanical properties.
In Tris buffer a mixture of octacalcium phosphate (OCP) and hydroxyapatite (HA) was present at 1h and 1d, followed by transformation to a strontium-containing hydroxyapatite (SrHA) after 7d and 28d. This process was delayed when cements were immersed in SBF. Compressive strength increased with Sr2+substitution up to Sr25 and decreased for higher Sr2+ substitutions in both Tris buffer and SBF. Overall higher values were recorded when SBF was used. Compressive strength was strongly influenced by the interlocking of the crystals and their morphology as seen by SEM. Cements resulted non cytotoxic.
Conclusions: A novel method to develop a bone substitute forming in-vitro SrHA as a final product by using a bioactive glass as a precursor was shown.
The immersion media influenced phases formed and properties of the CPC. SrHA formed as a final phase of the cement in both Tris and SBF. However SBF delayed transformation of OCP to HA and resulted in higher strength values. Further studies to assess how cements affect ALP activity and cell proliferation are ongoing.These novel injectable bioactive glass cements are promising materials for dental and orthopaedic applications in bone grafting.
Methods: Glasses were produced by progressively substituting strontium for calcium. Cements were prepared by mixing the glass powder and Ca(H2PO4)2 salt with a 2.5% solution of Na2HPO4. Samples were immersed in either 10 mL of Tris buffer solution or 10 mL of SBF for 1h, 1d, 7d and 28d. X- Ray Diffraction (XRD) was performed to assess phases formed after immersion. Compressive strength was measured after each time point and the fracture surfaces were studied under SEM. Cytotoxicity studies were performed using MC3T3-E1 osteoblasts. Cells were exposed to cement conditioned media and cell viability was assessed using an MTT assay.
Results: XRD showed that the amount of Sr2+ in the glass and the immersion media used influenced phases formed and mechanical properties.
In Tris buffer a mixture of octacalcium phosphate (OCP) and hydroxyapatite (HA) was present at 1h and 1d, followed by transformation to a strontium-containing hydroxyapatite (SrHA) after 7d and 28d. This process was delayed when cements were immersed in SBF. Compressive strength increased with Sr2+substitution up to Sr25 and decreased for higher Sr2+ substitutions in both Tris buffer and SBF. Overall higher values were recorded when SBF was used. Compressive strength was strongly influenced by the interlocking of the crystals and their morphology as seen by SEM. Cements resulted non cytotoxic.
Conclusions: A novel method to develop a bone substitute forming in-vitro SrHA as a final product by using a bioactive glass as a precursor was shown.
The immersion media influenced phases formed and properties of the CPC. SrHA formed as a final phase of the cement in both Tris and SBF. However SBF delayed transformation of OCP to HA and resulted in higher strength values. Further studies to assess how cements affect ALP activity and cell proliferation are ongoing.These novel injectable bioactive glass cements are promising materials for dental and orthopaedic applications in bone grafting.