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PubMed1994

Paradiaphyseal calcific tendinitis with cortical bone erosion.

OBJECTIVE: To determine the clinical, radiologic, and histologic features of calcific tendinitis with cortical bone erosion. METHODS: The records of 6 patients with paradiaphyseal calcific tendinitis and adjacent bone cortex erosion were reviewed. RESULTS: Calcific tendinitis involved the linea aspera in 4 patients, the bicipital groove in 1 patient, and the deltoid insertion in another. Calcium deposits were associated with cortical bone erosions, revealed on plain radiographs in 4 patients and computed tomography scans in 2. Bone scans were performed in 2 patients and showed local hyperfixation of the isotope. In 4 patients, suspicion of a neoplasm led to a biopsy. Calcium deposits appeared to be surrounded by a foreign body reaction with numerous giant cells. Apatite crystals were identified by transmission electron microscopy and elemental analysis in 1 surgical sample. CONCLUSION: Paradiaphyseal calcific tendinitis with cortical bone erosion is an uncommon presentation of apatite deposition disease.

Adult↗

PubMed2006

Prospective use of electrospun ultra-fine silicate fibers for bone tissue engineering.

Electrospinning involves the generation of a jet of viscous solution, and results in the formation of ultra-fine fibers. Silicate fibers prepared using this technology and via the sol-gel process were evaluated as scaffolds for bone tissue engineering. We found that human osteoblastic MG63 cells successfully adhered on individual silicate fibers, and proliferated on them. In an apatite-formation ability study, spherical particles covered the fibers after soaking in simulated body fluid for 7 days. Energy dispersive X-ray analysis revealed that Ca/P atomic ratio of the particles was similar to that of human bone. In addition, X-ray diffraction analysis revealed that crystalline structure of the particles agreed with that of apatite. These results suggest that electrospun silicate fibers are a potential candidate for scaffolding material in bone tissue engineering.

Apatites↗

PubMed1993

A new bioactive glass--ceramic as a coating material on titanium alloy.

Apatite--wollastonite-containing glass--ceramic (A--W . GC) has a strong ability to bond to bone and relatively high mechanical strength. Therefore, as a bulk material it has recently been applied clinically even in load-bearing sites. In this study, we modified A--W . GC by altering its composition ratio with the removal of CaF 2 and the addition of B 2O 3, and examined the potential use of the resulting new glass--ceramic as a material for coating on a titanium (Ti) alloy. The bioactivity of this new coating (NC) material and its bonding ability to bone were investigated mechanically and histologically. After implantation of the Ti alloy plate coated with this material into the tibiae of rabbits for 2, 3, 4, 8, and 25 weeks, a detaching test was performed. The detaching failure load of the NC plates was compared with those of A--W . GC plates, hydroxyapatite (HA) plates, and uncoated Ti alloy plates implanted in the same way. The failure load of NC was as high as that of A--W . GC for all periods, whereas it was significantly higher at 3 and 4 weeks than that of HA. Uncoated Ti alloy showed lower failure loads for all periods, differing significantly from the other materials. There was no breakage or detachment of the coating layer observed after the detaching test. Histological examinations by CMR, Giemsa surface staining, and SEM-EPMA showed that NC bonded directly to bone without any intervening soft tissue layer. A calcium--phosphorus-rich layer (apatite layer) was observed within the coating layer, as is the case in A--W . GC. These results indicate that this new glass--ceramic has earlier bone-bonding ability and high mechanical strength, making it a promising coating material.

Animals↗

PubMed1989

Transformation of biphasic calcium phosphate ceramics in vivo: ultrastructural and physicochemical characterization.

Specially prepared biphasic calcium phosphate (BCP) macroporous ceramics consisting of an intimate association of beta tricalcium phosphate (beta-TCP) and hydroxyapatite (HA) with beta-TCP/HA weight ratios of 15/85, 35/65, and 85/15 were implanted in surgically created periodontal osseous defects in dogs and recovered after 6 months. A decrease in average size of crystals in BCP ceramics and an increase in the size of microporosities in the surface and at the core of the ceramic after implantation were observed, indicating that in vivo dissolution has taken place. The resorbability (reflecting in vivo dissolution) of BCP ceramics depended on their beta-TCP/HA ratios, the higher the ratio, the greater the resorbability. The formation of microcrystals with crystallographic properties and Ca/P ratio similar to those of bone apatite crystals were also observed. The abundance of these crystals were directly related to the beta-TCP/HA ratio of the BCP ceramic before implantation. The formation of the bone apatite-like crystals may be due to the precipitation of calcium and phosphate ions released from the dissolving ceramic crystals (the beta-TCP component dissolving preferentially to the HA component). Results from this study suggested that one of the means of controlling resorbability (in vivo dissolution) of BCP ceramic is by varying its beta-TCP/HA ratio.

Animals↗

PubMed1991

Bone-bonding ability of P2O5-free CaO.SiO2 glasses.

An apatite- and wollastonite-containing glass-ceramic (A.W-GC) has been reported to form a tight bond with living bone through an apatite layer formed on its surface. This layer is considered to be formed by dissolution of Ca2+ and HSiO3- ions from the glass-ceramic into the surrounding body fluids. In order to confirm this proposed mechanism for the surface reaction of A.W-GC, three kinds of glass in the systems CaO-SiO2, CaO-SiO2-CaF2, and CaO-SiO2-P2O5 were implanted into the tibiae of rabbits for 3 or 8 weeks. Contact microradiography and SEM-EPMA showed that all three kinds of glass formed a Ca,P-rich layer in combination with a Si-rich layer on their surfaces within 3 weeks and formed a direct bond with bone via these layers. The detaching test, performed 8 weeks after implantation, showed that the loads required to detach the implants from the bone were almost equal for the phosphorus-free and the phosphorus-containing glasses. It was concluded that even P2O5-free CaO.SiO2 glass formed a Ca,P-rich layer on its surface and bonded tightly with living bone. If glasses and glass-ceramics release at least Ca2+ and HSiO3- ions, this would be sufficient for them to form the Ca,P-rich layer on their surfaces in vivo, enabling them to bond directly with bone.

Animals↗

PubMed1993

Organoapatites: materials for artificial bone. III. Biological testing.

This article reports on the in vivo testing of new artificial bone materials we have termed "organoapatites." These materials consist of mineral networks in which organic polymers are intimately dispersed by nucleation and growth of apatite crystals from a mother liquor containing the organic substances. Organoapatites were tested as implants in adult canine cortical bone for periods in the range from 12-35 weeks and fluorochromes were used in the model to investigate the kinetics of bone growth or repair. The analysis of histological samples was carried out using histomorphometric methods as well as fluorescence microscopy. Results showed excellent apposition of poly(amino acid) organoapatites with mineralized bone and fibrous encapsulation when a synthetic polyelectrolyte was the only organic component. This observation suggests that the molecularly dispersed organic dopant amounting to only 2-3% by weight of the microstructure can play a critical role in the tissue response to the implant. Relative to apatite controls, organoapatites were also found to have greater resistance to fragmentation in vivo and those containing amino acid units revealed interfacial bioerosion accompanied by regeneration of mineralized tissue. Design of organoapatite compositions and microstructures may therefore be useful in achieving the specific rate of biological response which is clinically desired.

Animals↗

PubMed1994

Ultrastructural study of the A-W GC-bone interface after long-term implantation in rat and human bone.

The interface between apatite- and wollastonite-containing glass-ceramic (A-W GC) and bone after long-term implantation was studied by scanning and transmission electron microscopy (SEM and TEM) using rat and human specimens. First, particles of A-W GC (100-220 microns in diameter) were implanted into rat tibiae, and specimens were prepared for observation at 24, 48, 72, and 96 weeks after the operation. These long-term specimens showed an A-W GC-bone interface different from that at an earlier stage, which was investigated in our previous studies. SEM showed that the Ca-P-rich layer was wider, suggesting that leaching of ions from the A-W GC had continued even after bonding with bone. In some regions, the material particles were evidently replaced by the bone. TEM showed that the intervening apatite layer had become indistinct, and that A-W GC had intermingled with bone at the interface. In some regions, the surface of the A-W GC was degraded. These findings suggest that the surface region of A-W GC is slowly replaced by bone. Second, a human bone specimen, which included A-W GC particles (300-700 microns in diameter) implanted as a bone filler for about 75 weeks was harvested and investigated. Excellent A-W GC-bone bonding was observed, and the ultrastructure of the interface was similar to that in rats after long-term implantation. This finding demonstrated that A-W GC possibly worked in human bone in the same way as in rat bone, showing excellent bioactivity.

Adult↗

PubMed1994

Calcium phosphate formation on sol-gel-derived bioactive glasses in vitro.

When soluble salts are used in the sol-gel processing of bioactive glasses, the resulting materials are not homogeneous. To produce homogeneous gel-glasses, a sol-gel method using all alkoxide precursors was developed. In this work the in vitro bioactivity of the new all-alkoxide gel-glasses is investigated. Three compositions in the system, CaO-P2O5-SiO2, were studied. Solid samples were soaked in Tris buffer and simulated body fluid (SBF), and the rate of formation of hydroxy carbonate apatite (HCA) on the surface of the glasses was measured by Fourier transform infrared spectroscopy. The solutions were analyzed before and after reaction by inductively coupled plasma. All compositions studied formed a hydroxy carbonate apatite (HCA) layer within 8 h in both test solutions. The HCA layer grew rapidly when SBF was used.

Apatites↗

PubMed2004

Evaluations of bioactivity and mechanical properties of poly (epsilon-caprolactone)/silica nanocomposite following heat treatment.

A composite material consisting of poly(epsilon-caprolactone) (PCL) and silica was prepared and evaluated as a bioactive bone substitute. The composite was synthesized by the co-condensation of tetraethyl orthosilicate and PCL and end-capped with triethoxysilane (Si-PCL). The as-prepared specimens were subjected to an initial heat treatment of 2 days at 60 degrees C, followed by further heat-treatments at 100 degrees C, 150 degrees C, and 200 degrees C for 24 h. The tensile mechanical properties of the heat-treated specimens were determined, and additional specimens were exposed to a simulated body fluid (SBF) for different periods of time. The SBF exposure led to the deposition of a layer of apatite crystals on the surface of the composites. It was found that increasing the second heat-treatment temperature produced an increase in tensile strength and Young's modulus of the composite but a decrease in the initial rate of apatite formation. These phenomena are explained in terms of the condensation reaction that takes place between the silanol groups in the silica and Si-PCL as the heat-treatment temperature is increased.

Apatites↗

PubMed2007

Plasma-controlled nanocrystallinity and phase composition of TiO2: a smart way to enhance biomimetic response.

This contribution sheds light on the role of crystal size and phase composition in inducing biomimetic apatite growth on the surface of nanostructured titania films synthesized by reactive magnetron sputtering of Ti targets in Ar+O(2) plasmas. Unlike most existing techniques, this method enables one to deposit highly crystalline titania films with a wide range of phase composition and nanocrystal size, without any substrate heating or postannealing. Moreover, by using this dry plasma-based method one can avoid surface hydroxylation at the deposition stage, almost inevitable in wet chemical processes. Results of this work show that high phase purity and optimum crystal size appear to be the essential requirement for efficient apatite formation on magnetron plasma-fabricated bioactive titania coatings.

Apatites↗

PubMed2004

Porous Ti-6Al-4V alloy fabricated by spark plasma sintering for biomimetic surface modification.

Porous compacts with both biological and biomechanical compatibilities and high strength were developed. Spherical powders of Ti-6Al-4V alloy, which were either as received or surface modified with the use of calcium ions by hydrothermal treatment (HTT), were fabricated by a spark plasma sintering process. The porous compacts of pure Ti were used as reference materials. Porosity was approximately 30%, and compressive strengths were 113 and 125 MPa for the as-received Ti alloy powders and those modified by the HTT process, respectively. The bending strength and elastic modulus of as-received Ti alloy powders were 128-178 MPa and 16-18 GPa, respectively. Each of the compacts was immersed in simulated body fluid (SBF). The amount of adsorption/precipitation of calcium phosphate through the compacts was measured by weight change and was observed by SEM. The compacts were covered with calcium phosphate after 2 weeks of immersion in SBF. The compacts of Ti alloy had plenty of precipitated apatite crystals, and modification by HTT accumulated more precipitation. Because calcium phosphate is a mineral component of bone, apatite, which is precipitated on the surface of the compacts, could adsorb proteins and/or drugs such as antibiotics. It is expected that a large amount of proteins and/or drugs could be impregnated when the porous compacts developed are used.

Alloys↗

PubMed2004

Surface modification of titanium implant by microarc oxidation and hydrothermal treatment.

Surface modification of titanium implant is processed by microarc oxidation and hydrothermal treatment. A porous surface with a biologically active bone-like apatite layer was formed. The apatite layer consists of very fine crystals and high crystallinity and is integrated with the titanium alloy substrate with a graded structure without a distinct interface. Such a bioactive layer is expected not only to enhance the bony ingrowth into the porous structure, but also to improve the interlocking between implant and bone.

Alloys↗

PubMed1990

Fluoride effects on bone crystals.

Fluoride is known to have biological effects on bone cells as well as physicochemical effects on bone crystals. This review concentrates on the latter. Fluoride increases the stability of the apatite lattice and decreases the solubility of the apatite crystals. In bone mineral, this ion has been shown to affect bone crystal structure by increasing crystallinity and reducing specific surface area. These changes in turn lead to changes in the chemistry of bone mineral. Bone mineral deposition is delayed by fluoride. This ion does not diffuse into bone already formed, but is incorporated during mineralization. Subsequently fluoride tends to accumulate in the most highly mineralized bone. Bone treated with fluoride has been shown to be more resistant to acid dissolution than normal bone, which would explain the reduced rate of resorption of fluoridated bone. The distribution of fluoride in bone is not uniform, but its net effect is to increase bone mineral density probably by an increased packing of bone crystals. Finally, there is a debate as to whether fluoride produces a bone of different quality. Whether these changes in the quality of bone will prove to be helpful or harmful remain to be determined.

Animals↗

PubMed2004

A study on biomineralization behavior of N-methylene phosphochitosan scaffolds.

Biomimetic growth of calcium phosphate over natural polymer may be an effective approach to constituting an organic/inorganic composite scaffold for bone tissue engineering. In this work, N-methylene phosphochitosan (NMPCS) was prepared via formaldehyde addition and condensation with phosphoric acid in a step that allowed homogeneous modification without obvious deterioration in chitosan (CS) properties. The NMPCS obtained was characterized by using FT-IR and elemental analysis. The macroporous scaffolds were fabricated through a freeze-drying technique. A comparative study on NMPCS and CS scaffold biomimetic mineralization was carried out in different media, i.e, a simulated body fluid (SBF) or alternative CaCl(2) and Na(2)HPO(4) solutions respectively. Apatite formation within NMPCS and CS scaffolds was identified with FT-IR, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) and X-ray diffractometery (XRD). The results revealed alternate soaking of the scaffolds in CaCl(2) and Na(2)HPO(4) solutions was better than soaking in SBF solution alone in relation to apatite deposition on the scaffold pore walls. Biomineralization provides an approach to improve nature derived materials, e.g., chitosan derivative NMPCS properties e.g., compressive modulus, etc. SEM image of a NMPCS/apatite composite scaffold.

Apatites↗

PubMed1986

Crystal-associated matrix components in rat incisor enamel. An electron-microscopic study.

Sections of glutaraldehyde-OsO4-fixed, plastic-embedded rat incisor enamel were left untreated, stained, decalcified (1% formic acid in 10% sodium citrate), or decalcified-stained. The presence of apatite crystals was monitored with electron diffraction. After brief decalcification and staining, apatite crystals and matrix components were visualized in the same field. The ghost was continuous with crystal fragments, and the coat appeared as a dense line next to crystals and ghosts. Position of ghosts and crystals at the ameloblast-enamel junction (AEJ) of the secretion zone suggested that there may be a lag of no more than 1/5 min between the elaboration of ghost and crystal. A major change in enamel morphology occurs between the AEJ and the deep enamel of the secretion zone. The ghost becomes thinner, the coat more pronounced, and the crystal enlarges. There is only little change from the deep secretion to the maturation zone enamel.

Animals↗

PubMed1980

Analysis of the crystal arrangement in collagen fibrils of mineralizing turkey tibia tendon.

Mineralized pieces of tendons from the tibio-tarsus of turkeys were (i) shock-frozen, freeze-dried, embedded and cut without staining, or (ii) fixed, embedded and stained after sectioning. Micrographs were taken with an electron microscope on longitudinally cut sections. The center-to-center distances of neighboring apatitic needles within collagen fibrils were measured. For shock-frozen and freeze-dried specimens, the average of these distances is 4.7 nm and the most frequent value 4.2 nm; for the fixed and stained specimens, 3.8 nm and 3.6 nm, respectively. Laser diffraction of the electron micrographs showed a dumbbell-like intensity pattern (two diffuse maxima of intensity on the equator, one on each side of the central spot), giving an average distance of about 6 nm. This value represents the upper range of the direct measurements. The measurements demonstrate that the arrangement of the collagen microfibrils is mainly preserved during mineralization. However, using laser diffraction, distances of 9-11 nm were also observed. Such large distances can also be demonstrated by X-ray diffraction on collagen fibrils stained under special conditons. this may indicate that special conditions of apatitic mineralization or staining may alter the arrangement of the microfibrils.

Animals↗

PubMed1993

ESR study of 13C-enriched carbonated calciumapatites precipitated from aqueous solutions.

The ESR spectrum of X-irradiated carbonated apatites precipitated from aqueous solutions was studied at carbonate contents ranging from approximately 5.4 up to 12.4 wt%. 12C- as well as 13C-enriched samples were prepared and examined with ESR after dying until constant weight at 25 degrees C and 400 degrees C. In these carbonated apatites, two CO3(3-) radicals were detected, one of which is derived from B-type carbonate situated at a phosphate lattice site. The other CO3(3-) most probably arises from CO3(2-) ions situated at OH- lattice sites. In contradistinction to the B-type contribution, the A-type contribution to the overall ESR signal decreases in absolute terms with increasing carbonate concentration. In addition, the line shape and the complete set of principal g-values of the A1-signal found in previous studies could be determined, corroborating the assignment of A1 to a surface O- ion.

Apatites↗

PubMed1975

The effect of D-penicillamine of the skeletal development of rat foetuses.

Rats received 20, 50 or 100 mg/animal D-penicillamine i.p. twice daily on days 15, 16, 17, 18, and 19 of gestation, i.e. a total dose of 200, 500 resp. 1000 mg/animal. At all dosages the number of fetal resorptions did not increase significantly. Weight of the 20 day old embryos as well as length of the long bones in the extremities in the 100 mg-group showed a significant decrease. Numerous skeletal alterations could be observed in the 1000 mg-group such as absence, deformations or incomplete mineralisation of bones. Light microscopic examinations revealed an inhibition of the ossification as well as a decrease of number and size of the trabecula and of the thickness of the perichondrial bone sheath. A swelling of the collagenous fibrils can be demonstrated with the electron microscope. The first apatite crystals aggregate in collagen-free areas. The fusion of these aggregates to homogenously mineralized trabecula is inhibitied. In contrast to bones from untreated embryos, mineralized areas show varying content of collagen and apatide crystals. A regular spatial relationship between apatite crystals and collagenous fibrils does not develop. These findings show that even after the so-called "critical period" malformations can be pproduced by substances which disturb synthesis and maturation of the mesenchymal intercellular substance.

Abnormalities, Drug-Induced↗