Characterization and thermal decomposition of synthetic carbonate apatite powders prepared using different alkali metal salts.

Two types of synthetic carbonate apatite [potassium-containing carbonate apatite (CAK) and sodium-containing carbonate apatite (CANa)] were prepared and characterized by thermogravimetric analysis, X-ray diffraction analysis (XRD) and Fourier transform infrared spectroscopy. The chemical formulas of carbonate apatite were determined to be CaK(PO)(CO)(OH) and CaNa(PO)(CO)(OH), respectively. Thermogravimetric analysis showed that the final weight loss at 1,200°C reached about 11.

Characterization and in vitro evaluation of biphasic α-tricalcium phosphate/β-tricalcium phosphate cement.

Biphasic calcium phosphate consisting of hydroxyapatite (HA) and β-tricalcium phosphate(β-TCP) is an excellent bone substitute with controllable bioresorbability. Fabrication of biphasic calcium phosphate with self-setting ability is expected to enhance its potential application as bone substitute. In this study, mixtures of α-TCP and β-TCP with various compositions were prepared through α-β phase transition of α-TCP powder at 1000°C for various periods.

Effects of the method of apatite seed crystals addition on setting reaction of α-tricalcium phosphate based apatite cement.

Appropriate setting time is an important parameter that determines the effectiveness of apatite cement (AC) for clinical application, given the issues of crystalline inflammatory response phenomena if AC fails to set. To this end, the present study analyzes the effects of the method of apatite seed crystals addition on the setting reaction of α-tricalcium phosphate (α-TCP) based AC. Two ACs, both consisting of α-TCP and calcium deficient hydroxyapatite (cdHAp), were analyzed in this study.

Fabrication of bone cement that fully transforms to carbonate apatite.

The objective of this study was to fabricate a type of bone cement that could fully transform to carbonate apatite (CO3Ap) in physiological conditions. A combination of calcium carbonate (CaCO3) and dicalcium phosphate anhydrous was chosen as the powder phase and mixed with one of three kinds of sodium phosphate solutions: NaH2PO4, Na2HPO4, or Na3PO4. The cement that fully transformed to CO3Ap was fabricated using vaterite, instead of calcite, as a CaCO3 source.

Fabrication of carbonate apatite blocks from set gypsum based on dissolution-precipitation reaction in phosphate-carbonate mixed solution.

Carbonate apatite (CO3Ap), fabricated by dissolution-precipitation reaction based on an appropriate precursor, is expected to be replaced by bone according to bone remodeling cycle. One of the precursor candidates is gypsum because it shows self-setting ability, which then enables it to be shaped and molded. The aim of this study, therefore, was to fabricate CO3Ap blocks from set gypsum.

Effect of precursor's solubility on the mechanical property of hydroxyapatite formed by dissolution-precipitation reaction of tricalcium phosphate.

The effect of the solubility of the precursors, alpha tricalcium phosphate (α-TCP) and beta tricalcium phosphate (β-TCP) on the mechanical strength of hydroxyapatite (HAp) bone substitute was investigated. Uniaxially pressed block starting from these precursors were treated hydrothermally with 1 mol/L of ammonia solution at 200°C for various durations. XRD analysis revealed that α-TCP block took 3 h whereas β-TCP block took 240 h for complete transformation to HAp.

Fabrication of microporous calcite block from calcium hydroxide compact under carbon dioxide atmosphere at high temperature.

Effects of carbonation temperature and compacting pressure on basic properties of calcite block were studied using Ca(OH)2 compact made with 0.2-2.0 MPa and their carbonation at 200-800ºC for 1 h.

Fabrication of solid and hollow carbonate apatite microspheres as bone substitutes using calcite microspheres as a precursor.

Spherical carbonate apatite (CO3Ap) microspheres approximately 1 mm in diameter were fabricated by granulation of calcium hydroxide around a core followed by carbonation and phosphatization through dissolution-precipitation reaction. CO3Ap microspheres with high uniformity could not be achieved without using a core. Solid CO3Ap microspheres were obtained using a calcite core whereas hollow CO3Ap microspheres were obtained using a NaCl core.

Preparation of Sr-containing carbonate apatite as a bone substitute and its properties.

Sr-containing carbonate apatite (SrCAp) specimens of varied Sr contents, ranging from 0 to 13.3 mol%, were prepared through a phosphate treatment of set gypsum-and-carbonate mixture at 100°C for 7 days. Effects of Sr content in SrCAp on microstructure, osteoblast-like cell (MC3T3-E1) attachment and proliferation, and alkaline phosphatase (ALP) activity were evaluated.

Hydrothermal calcium modification of 316L stainless steel and its apatite forming ability in simulated body fluid.

To understand the feasibility of calcium (Ca) modification of type 316L stainless steel (316L SS) surface using hydrothermal treatment, 316L SS plates were treated hydrothermally in calcium chloride (CaCl(2)) solution. X-ray photoelectron spectroscopic analysis revealed that the surface of 316L SS plate was modified with Ca after hydrothermal treatment at 200°C. And the immobilized Ca increased with CaCl(2) concentration.

Fabrication of low-crystalline carbonate apatite foam bone replacement based on phase transformation of calcite foam.

Carbonate apatite (CO(3)Ap) foam may be an ideal bone substitute as it is sidelined to cancellous bone with respect to its chemical composition and structure. However, CO(3)Ap foam fabricated using α-tricalcium phosphate foam showed limited mechanical strength. In the present study, feasibility of the fabrication of calcite which could be a precursor of CO(3)Ap was studied.

Tissue-response to calcium-bonded titanium surface.

Our previous study demonstrated that calcium-bonded titanium surface (Ca-Ti) can be obtained by hydrothermal reaction between titanium (Ti) and CaCl(2) and that bone-apatite like formation was observed after immersion in simulated body fluid. The purpose of the study was to determine the in vivo response to Ca-Ti surface using a rodent tibia model. Cylinders of commercially pure Ti were divided into three groups: (1) untreated group; (2) NaOH+hTi group: soaked in 5 mol/L NaOH solution at 60 degrees C then heated at 400 degrees C for 1 h; and (3) Ca-Ti group: hydrothermally treated in the presence of 10 mmol/L CaCl(2) at 200 degrees C for 24 h.

Fabrication of carbonate apatite block based on internal dissolution-precipitation reaction of dicalcium phosphate and calcium carbonate.

In this study, we investigated a novel method for fabrication of carbonate apatite block without ionic movement between precursor and solution by using precursor that includes all constituent ions of carbonate apatite. A powder mixture prepared from dicalcium phosphate anhydrous and calcite at appropriate Ca/P ratios (1.5, 1.

Effects of sintering temperature on physical and compositional properties of alpha-tricalcium phosphate foam.

Effects of sintering temperature on the physical and compositional properties of alpha-TCP foam fabricated using the polyurethane foam method were examined. When a polyurethane foam coated with alpha-TCP slurry was sintered at 1,400-1,550 degrees C, alpha-TCP foam having basically the same fully interconnected porous structure was produced although shrinkage occurred with increasing sintering temperature. On porosity of the alpha-TCP foam, a higher foam porosity of 95% was obtained when sintered at 1,400 degrees C as compared to the 90% porosity obtained at a higher sintering temperature of 1,550 degrees C.

Effects of added mannitol on the setting reaction and mechanical strength of apatite cement.

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.

Effect of temperature on crystallinity of carbonate apatite foam prepared from alpha-tricalcium phosphate by hydrothermal treatment.

The effect of temperature on crystallinity of carbonate apatite (CAp) foam prepared from alpha-tricalcium phosphate (alpha-TCP) foam by hydrothermal treatment was investigated in the present study. The alpha-TCP foams were prepared through a conventional sintering method using polyurethane foam as template. Then, the resultant alpha-TCP foams were hydrothermally treated with Na2CO3 aqueous solution at 100 degrees C, 150 degrees C and 200 degrees C for 72 h.

Fabrication of freeform bone-filling calcium phosphate ceramics by gypsum 3D printing method.

Transformation of gypsum model fabricated by three-dimensional printing (3DP) into hydroxyapatite (HA) by treating in ammonium phosphate solution is possible. However, 3DP powder supplied by the manufacturer contains unknown additives which may be questionable for biomaterials. Accordingly, pure plaster of Paris (POP) powder was used for fabrication in the present study.

Fabrication of B-type carbonate apatite blocks by the phosphorization of free-molding gypsum-calcite composite.

B-type carbonate apatite (CO3Ap) block may be an ideal artificial bone substitute because it is closer in chemical composition to bone mineral. In the present study, the feasibility to fabricate CO3Ap blocks was investigated using compositional transformation, which was based on the dissolution-precipitation reaction of a gypsum-calcite composite with free-molding behavior. For the compositional change, or phosphorization, gypsum-calcite composites of varying CaCO3 contents were immersed in 1 mol/L (NH4)3PO4 aqueous solution at 100 degrees C for 24 hours.

Effects of liquid phase on basic properties of alpha-tricalcium phosphate-based apatite cement.

Effects of liquid phase on the basic properties of alpha-tricalcuim phosphate (alpha-TCP)-based cement, BIOPEX, were investigated by employing three liquid phases: distilled water, neutral sodium hydrogen phosphate solution, and succinic acid disodium salt solution containing sodium salt of chondroitin sulfate. When mixed with neutral sodium hydrogen phosphate or succinic acid disodium salt solution, the initial setting times of the cement were 19.4 +/- 0.

Fabrication of low-crystallinity hydroxyapatite foam based on the setting reaction of alpha-tricalcium phosphate foam.

Low-crystallinity hydroxyapatite (HAP) foam is an ideal material for bone substitutes and scaffolds for bone tissue regeneration, because its interconnected pores provide the space for cell growth and tissue penetration, and its composition induces excellent tissue response and good osteoconductivity. In this study, the feasibility of low-crystallinity HAP foam fabrication was evaluated based on the phase transformation reaction or the so-called dissolution-reprecipitation reaction of alpha-tricalcium phosphate (alpha-TCP) foam granules. When alpha-TCP foam granules were placed in water at 37 degrees C for 1 day, no reaction was observed.

Comparison of the effects of added alpha- and beta- tricalcium phosphate on the basic properties of apatite cement.

Effects of added alpha-tricalcium phosphate (alpha-TCP) and beta-TCP were investigated to shed light on the setting reaction of apatite cement (AC) consisting of tetracalcium phosphate (TTCP) and dicalcium phosphate anhydrous8 (DCPA). Added beta-TCP showed no reactivity, and thus resulted in extended setting time and decreased mechanical strength. In contrast, alpha-TCP dissolved to supply calcium and phosphate ions after initial apatite crystal formation by the reaction of TTCP and DCPA.

Effect of molding pressure on fabrication of low-crystalline calcite block.

We have reported that low-crystalline porous calcite block, which is useful as a bone substitute or a source material to prepare apatite-type bone fillers could be fabricated by exposing calcium hydroxide compact to carbon dioxide gas saturated with water vapor. In the present study, we investigated the effect of molding pressure on the transformation of calcium hydroxide into calcite and the mechanical strength of the carbonated compact. Transformation into calcite was almost completed within 72 h, however, a small amount of Ca(OH)(2) still remained unreacted at higher molding pressure because of incomplete penetration of CO(2) gas into the interparticle space due to dense packing of Ca(OH)(2) particles.

Long-term follow-up of composite resin restorations with self-etching adhesives.

Objective: To test the hypothesis, derived from a previous short-term (7-day) assessment, that the absence of conventional pulp protection is not responsible for long-term pulp complications of composite resin restorations with self-etching adhesives.

Methods: All 150 patients who received the restorations with self-etching adhesives were recalled at least 2 years after the placement of restorations. Of the 47 patients (31%) who responded, 106 restorations aged from 2.

Fabrication of porous low crystalline calcite block by carbonation of calcium hydroxide compact.

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.

Fabrication of biporous low-crystalline apatite based on mannitol dissolution from apatite cement.

Biporous (macro- and microporous) calcium phosphate gains much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, we evaluated the feasibility of biporous, low-crystalline apatite based on dissolution of mannitol from self-setting apatite cement (Biopex). Mannitol--known as a biocompatible, easily dissolved monosaccharide alcohol--was recrystallized to obtain larger crystals.