ABSTRACT
Apatite cement containing porogen can be a useful material for the fabrication of biporous (macro- and microporous) apatite, which has gained much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, the effects of added mannitol on the setting reaction and mechanical strength of apatite cement were evaluated. Apatite cements containing 0-40 wt% of mannitol were prepared and allowed to set in 0.9% saline kept at 37 degrees C for 1-7 days. Although the diametral tensile strength (DTS) value increased with time, it decreased with the amount of added mannitol. SEM observation and XRD analysis revealed that mannitol had no inhibitory effect on the transformation reaction of apatite cement to apatite. It was thus concluded that mannitol was a good candidate for the fabrication of biporous apatite because it is biocompatible, exhibits satisfactory dissolution behavior, and that it caused no inhibitory effects on the compositional transformation to apatitic material.
Subject(s)
Bone Cements/chemistry , Chondroitin Sulfates/chemistry , Hydroxyapatites/chemistry , Mannitol/chemistry , Succinates/chemistry , Biocompatible Materials/chemistry , Bone Substitutes/chemistry , Chondroitin Sulfates/ultrastructure , Crystallization , Drug Combinations , Materials Testing , Stress, Mechanical , Sugar Alcohols/chemistry , Tissue Scaffolds/chemistryABSTRACT
Calcium carbonate (CaCO(3)) has been widely used as a bone substitute material because of its excellent tissue response and good resorbability. In this experimental study, we propose a new method obtaining porous CaCO(3) monolith for an artificial bone substitute. In the method, calcium hydroxide compacts were exposed to carbon dioxide saturated with water vapor at room temperature. Carbonation completed within 3 days and calcite was the only product. The mechanical strength of CaCO(3) monolith increased with carbonation period and molding pressure. Development of mechanical strength proceeded through two steps; the first rapid increase by bonding with calcite layer formed at the surface of calcium hydroxide particles and the latter increase by the full conversion of calcium hydroxide to calcite. The latter process was thought to be controlled by the diffusion of CO(2) through micropores in the surface calcite layer. Porosity of calcite blocks thus prepared had 36.8-48.1% depending on molding pressure between 1 MPa and 5 MPa. We concluded that the present method may be useful for the preparation of bone substitutes or the preparation of source material for bone substitutes since this method succeeded in fabricating a low-crystalline, and thus a highly reactive, porous calcite block.
Subject(s)
Biocompatible Materials/chemical synthesis , Calcium Carbonate/chemistry , Calcium Hydroxide/chemistry , Nanostructures/chemistry , Nanostructures/ultrastructure , Carbon/chemistry , Crystallography/methods , Elasticity , Hardness , Particle Size , Porosity , Surface Properties , Tensile StrengthABSTRACT
It is well known that apatite cement causes inflammatory response if it is exposed to blood before setting. In this respect, the hemostatic procedure is very important. However, it has not been clarified how initial hemostasis affects the other basic properties of apatite cement. In the present study, the effect of initial hemostasis on the setting reaction was simulated by allowing the apatite cement paste to be hardened in an incubator for 1 to 30 minutes and then immersed in saline up to 7 days. We found faster transformation of apatite cement to apatitic mineral and higher mechanical strength of the set mass when the cement paste underwent a longer pre-hardening period. We also found that earlier exposure of apatite cement to saline resulted in a set mass with larger porosity. It is thought that the larger porosity of the cement is caused by the penetration of liquid into the cement paste, thus leading to lower mechanical strength and slower transformation of the apatite cement to apatitic mineral. We concluded, therefore, that hemostatic procedure is important not only to prevent inflammatory response but also to obtain a set mass with higher mechanical strength and faster transformation to apatitic mineral.
Subject(s)
Calcium Phosphates , Chondroitin Sulfates , Dental Cements , Hemostatic Techniques , Hydroxyapatites , Succinates , Analysis of Variance , Calcium Phosphates/chemistry , Chondroitin Sulfates/chemistry , Crystallography, X-Ray , Dental Cements/chemistry , Dental Stress Analysis , Hardness , Hydroxyapatites/chemistry , Materials Testing , Microscopy, Electron, Scanning , Porosity , Succinates/chemistryABSTRACT
Biopex sets upon mixing with its liquid phase due to chelate reaction between sodium succinate and calcium phosphate, then gradually transforms to apatite. As a result of apatite formation, set Biopex shows excellent tissue responses and good osteoconductivity. However, Biopex would be washed out when the paste is exposed to body fluid before its setting reaction. Washed out cement causes an inflammatory response. In this investigation, therefore, sodium alginate was added to the liquid phase of Biopex and its effects on washout properties and transformation to apatite were studied. We found that cement remaining ratio, an index of the anti-washout property, of the Biopex increased by increasing the amounts of added sodium alginate to reach 100% when the liquid phase of Biopex contained 0.6% or more sodium alginate. Biopex gradually transformed to apatite regardless of the amount of added sodium alginate at least when the concentration of the sodium alginate in the liquid phase was 1.0% or less. It is concluded therefore, that addition of sodium alginate is very useful for Biopex to acquire the anti-washout property.
