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PubMed1977

Ultrastructural study of apatite crystal dissolution in human dentine and bone.

The width and thickness of normal apatite monocrystals were determined in human dentine and alveolar bone on non-decalcified thin sections made perpendicular to the c axis. A mean width (L) of 364.50 A +/- 14.50 A and 562.10 A +/- 19 A was respectively found for dentine and bone monocrystals, whereas their mean thickness (E) was respectively 103.30 A +/- 2.70 A and 79.10 A +/- 3.10 A. The study of the ratio L.E.-1 for dentine and bone monocrystals showed a plate-like configuration which was more accentuated in bone crystals. Apatite crystal dissolution was studied during the carious process in dentine and bone resorption during advanced periodontal lesions. It could be shown that, in both conditions, one or several central core lesions developed along the c axis of the crystals. These central core lesions, extending laterally along (100) planes, progressively fused together, leading to the splitting up of the monocrystals into two thin plates by a complete destruction of the central part of the monocrystal.

Adolescent↗
PubMed1992

Evaluation of the apical sealing ability of apatite root canal sealer.

The apical sealing ability of a tricalcium phosphate sealer was compared with that of three other sealers. Seventy roots of human incisors were cleansed and shaped and randomly assigned to one of seven groups of ten roots each. The root canal systems were obturated with gutta-percha and one sealer using the lateral-vertical condensation technique. The canal was sealed with Roth's sealer, Sealapex, Kerr root canal sealer, or Sankin apatite root sealer (Type I, II, or III). One group was filled with gutta-percha without sealer to serve as a control. After the roots were immersed in silver nitrate, the degree of dye penetration was measured under a dissecting microscope. Results indicated that Sealapex had the best sealing ability, followed by Sankin apatite root sealer, Type II. Roth's cement showed the most dye penetration. Canals that were obturated without sealer showed significantly greater apical leakage.

Apatites↗
PubMed1992

Comparison of the acute inflammation induced by calcium pyrophosphate dihydrate, apatite and mixed crystals in the rat air pouch model of a synovial space.

Pure monoclinic or triclinic calcium pyrophosphate dihydrate (CPPD) crystals, apatite crystals or mixtures of these crystals were injected into the synovial-like space created by the rat air pouch to compare the acute inflammation induced by these crystals. Fluids were withdrawn 6 h after injection and examined for leukocyte counts, protease, prostaglandin E2 (PGE2) and tumor necrosis factor (TNF) levels. CPPD crystals (especially monoclinic CPPD) induced higher numbers of leukocytes, and more protease, PGE2 and TNF than apatite. CPPD seemed to play a predominant role in the acute inflammation induced by mixed crystals.

Animals↗
PubMed2006

Preparation of germanium apatite and its cytotoxicity.

Germanium apatite was synthesized via the solid-state reaction between GeO(2) and (NH(4))(3)PO(4). The synthesized materials were characterized using XRD, and thermal analysis was carried out using TG-DTA. Ge(2)P(2)O(7) was preferentially produced at temperatures between 300-900 degrees C, and at temperatures above 1000 degrees C, germanium apatite (Ge(5)O(PO(4))(6), GeAp) was synthesized. In solubility tests, 0.36% and 0.65% of Ge ions were liberated from GeAp powder in distilled water at 37 and 80 degrees C after four weeks, respectively. A GeAp aqueous solution maintained at 37 degrees C was strongly acidic with a pH=1.67 after four weeks. The growth rate of human adult gingival fibroblast cells in a medium that included GeAp, HA, and GeO(2) was investigated. The growth rate of the cells in a 0.1 mg/ml GeAp medium was almost the same as that in the control. The cell growth was restricted in a 1.0 mg/ml GeAp medium, whereas the cell growth in a pH-adjusted 1.0 mg/ml GeAp medium at pH=7.60 was higher than that in non-adjusted medium at pH = 7.06.

Apatites↗
PubMed2006

[Experimental study of fast formation of biomimetic apatite coatings on pure titanium surface].

OBJECTIVE: To investigate calcium-phosphate coating on commercial pure titanium substrate using a fast biomimetic procedure. METHODS: The titanium specimens were divided into two groups, group A and group B. The specimens of group A were only treated with the mixture of H2SO4/HCl for 30 min. The specimens of group B were treated with the mixture of H2SO4/HCl for 30 min, immersed into 5 mol/L NaOH solution at 60 degrees C for 24 h, and then heated to 600 degrees C and maintained for 1 h. All specimens were soaked into simulated body fluid-A (SBF) and SBF-B for each day. The surface morphology was observed by field scanning electron microscopy. RESULTS: Dense calcium-phosphate coating deposited on all the titanium surfaces of two groups. The calcium-phosphate coating consisted of spheric structure with a diameter of 1 approximately 3 microm, which was proved to be hydroxycarbonate apatite with the analysis of X-ray diffraction. CONCLUSIONS: Thin hydroxycarbonate apatite coating can deposited on pure titanium using a fast biomimetic procedure.

Apatites↗
PubMed1990

Production of cerium-apatite in sound and carious dental enamel under in vitro conditions.

Incipient dental caries--according to up-to-date concepts in dental research--means a demineralization without cavity formation. At this stage the carious process is reversible, and remineralization can be achieved in the presence of locally applied fluorides. In chrystalchemical experiments, however, by treating natural apatites with lanthanides, [Ce, La, Pr, Nd, Sm, Eu, Tb ... Y, Sc] a more resistant complex could be developed. In this study extracted human molar teeth were kept for 60 days in Cerium (III)-nitrate solution, in order to investigate the incorporation of Ce3+ into human sound and carious enamel by light-microscopic-, and electron microprobe methods. Ce3+ was incorporated in sound enamel as well as into the incipient carious lesion, showing the histological characteristics of a remineralizing lesion. The mean values of the microprobe analysis data showed an increase in Ce3+ changing place with the Ca2+ the developing cerium-apatite being more hard and resistant from a mineralophysical point of view.

Apatites↗
PubMed1989

Bonding behavior of a glass-ceramic containing apatite and wollastonite in segmental replacement of the rabbit tibia under load-bearing conditions.

Glass-ceramic implants containing apatite and wollastonite were studied under load-bearing conditions in a segmental replacement model in the tibia of the rabbit. Alumina-ceramic implants were used as a control. A sixteen-millimeter segment of the middle of the shaft of the tibia was resected at a point distal to the junction of the tibia and the fibula. The defect was replaced by a fifteen-millimeter-long hollow, cylindrical implant that was fixed by intramedullary nailing using a Kirschner wire. Two groups of eight rabbits each (one group with a glass-ceramic implant and the other with an alumina implant) were killed twelve weeks after implantation. Two similar groups were killed twenty-five weeks after implantation. The segment of the tibia that contained the implant was excised and tension-tested. The load to failure of glass-ceramic implants containing apatite and wollastonite increased with time. The loads to failure of the glass-ceramic and alumina implants at twelve weeks after implantation were 19.8 +/- 7.06 and zero newtons, respectively. The loads to failure of glass-ceramic and alumina implants at twenty-five weeks after implantation were 126.4 +/- 32.54 and 19.6 +/- 13.92 newtons, respectively. No glass-ceramic implants broke. A calcium-phosphorus layer at the interface of the glass-ceramic and the bone was observed by scanning electron microscopy and electron-probe microanalysis. There was no interposition of soft tissue between the glass-ceramic and the bone, as observed by Giemsa surface staining.

Aluminum Oxide↗
PubMed1988

Universal spondylodiscitis in a patient with erosive peripheral arthritis and apatite crystal deposition.

A patient with erosive peripheral arthritis in whom vasculitis and monoclonal IgG kappa paraprotein were associated with sacroiliitis and widespread destruction of intervertebral discs is reported. Crystals resembling apatite were identified in intervertebral disc material, and we postulate that the discitis was accelerated by apatite deposition. Our case illustrates a unique example of axial involvement in rapidly progressive joint disease.

Adult↗
PubMed1987

In vitro albumin binding on apatite crystals from developing enamel.

Serum proteins have never been described in enamel as they have been in dentin or bone where they are bound to apatite, may be because of the specific organic/crystal relationship which makes enamel crystals different from the other biological apatites. In the present study, crystals from bovine developing enamel have been isolated to test their ability to bind serum albumin in vitro. Those crystals, although naturally coated with enamelins proved to be able to bind gold-labelled serum albumin. Consequently, free binding sites exist at the surface of these biological crystals. It is suggested that the 'sheath' surrounding crystals in TEM observations is the fixed aspect of a dynamic process in vivo. Finally, the lack of blood proteins in enamel cannot be attributed to a particular property of enamel crystallites.

Albumins↗
PubMed1986

[Presence of newberyite in the right kidney and carbonated apatite in the left kidney in a patient with recurrent urinary infections].

In about 20% of the cases, urolithiasis is directly linked to chronic urinary tract infection by urea splitting bacteria, essentially Proteus mirabilis. The stones are generally composed of struvite and carbonate apatite which usually occur as staghorn calculi feared because of their obstructive and infectious consequences that cause important renal damage. The case of a 48 year-old woman with chronic urinary infection is described whose right kidney showed a staghorn calculus essentially composed of newberyite, a very rare constituent of urolithiasis, and whose left kidney contained three carbonate apatite calculi. Clinical and technical examinations, relations between the two mineral constituents are discussed in this paper with a review of the literature on the subject.

Apatites↗
PubMed1981

[Chronic polyarthrosynovitis in the goat: histological and physicochemical study of an animal model of apatite crystallopathic rheumatism].

The aim of this paper is to describe clinical pattern and pathogenesis of spontaneous chronic polyarthritis observed in Swiss goats. Roentgenograms, histologic findings, ultrastructural study and microprobe analysis of synovium samples show apatite microcrystal deposit ion. Thus this spontaneous goat disease may be related to apatite microcrystal deposit ion disease in man, so called crystallopathic-hydroxyapatite rheumatism.

Animals↗
PubMed1994

[Apatite rheumatism].

Acute periarthritis is a typical example of apatite arthropathy related to intratendinous calcifications. The attack may be followed by virtually complete radiological disappearance of the calcification. Within the joint one may exceptionally demonstrate the presence of hydroxyapatite crystals in the synovial fluid during a fluxional flare-up of arthrosis or in the fluid withdrawn from the humeral joint following rupture of calcification in the glenohumeral cavity. More frequently, the crystals are detected in the synovial fluid from joints damaged by advanced destructive arthrosis. These crystals are sometimes associated with calcium pyrophosphate crystals (mixed pyrophosphatic and apatitic arthropathy).

Adult↗
PubMed1996

Self-setting, bioactive, and biodegradable TTCP-DCPD apatite cement.

Tetracalcium phosphate-dicalcium phosphate dihydrate self-setting apatite cement mixed with low-crystallized seed hydroxyapatite is similar to the host bone in degree of crystallinity. The bonding strength of this cement with hydroxyapatite-coated titanium rods was twice that with noncoated titanium and four times that with stainless steel. Histologically, TTCP-DCPD apatite cement incorporated into the tibia of rabbits were degraded, absorbed, and replaced by the normal body trabeculae rapidly. The mechanical strength of the cement disk intercalated into a gap made in the rabbit tibiae increased to 73% of that of the normal tibia at 10 weeks concurrently with the decrease in bone mineral density of the disk toward that of the normal tibia, in which bony replacement of the disk was observed also histologically. These bioactive and biodegradative characters of this cement are due to the similarity of its degree of crystallinity to that of the host bone, and could expand its clinical applications.

Animals↗
PubMed1996

A self-setting TTCP-DCPD apatite cement for release of vancomycin.

Vancomycin (VCM), a methiciline-cefem resistant Staphylococcus aureus (MRSA)-specific antibiotic, was incorporated in a self-setting tetracalcium phosphate (TTCP)-dicalcium phosphate dihydrate (DCPD) apatite cement that hardened isothermally into a hydroxyapatite (HAP) phase with crystallinity similar to that of host bone. Effective release of VCM into PBS lasted for 2 weeks from cements containing 1% VCM and for longer than 9 weeks from cements containing 5% VCM. The rate of release of VCM differed between cements with different crystallinities as well as between the two dissolution media, PBS and simulated body fluid. Mean concentration of VCM in the bone marrow tissue released from cements containing 5% VCM was 20 times the minimum inhibitory concentration 3 weeks after implantation in bone. Direct contact with new bone was observed with the cements containing 1% VCM. Slow delivery of VCM from a self-setting TTCP-DCPD apatite cement with low crystallinity could be used to treat MRSA osteomyelitis.

Animals↗
PubMed2000

The effect of alkali- and heat-treated titanium and apatite-formed titanium on osteoblastic differentiation of bone marrow cells.

This study was based on the hypothesis that osteogenesis is enhanced by growth of osteogenic cells on an apatitic surface. To test this hypothesis, the behavior of rat bone marrow cells on these surfaces was examined: commercially pure titanium (Cp Ti), alkali- and heat-treated titanium (AH Ti), and AH Ti incubated in a simulated body fluid to deposit crystalline hydroxyapatite on the surface (Ap Ti). The alkaline phosphatase (ALP) activity of the cells cultured on Ap Ti was significantly higher at day 7 and day 14 than the ALP activity observed for the other titanium surfaces. At day 14, the ALP activity on AH Ti was significantly increased compared with the ALP activity on Cp Ti. The amount of DNA per well increased nearly in parallel for each titanium. However, northern blot analysis at day 14 revealed that expression of osteocalcin and alpha1(I) collagen mRNA was higher in the cells cultured on Ap Ti than the cells cultured on AH Ti. The cells cultured on Cp Ti showed the lowest mRNA levels. After 7 days of cell-free culture in medium supplemented with 15% serum, X-ray photoelectron spectroscopy (XPS), and thin-film X-ray diffraction (TF-XRD) analysis showed that calcium phosphate had been deposited on the AH Ti (resulting in an increase in thickness with time). No phosphate was detected on the Cp Ti, even after day 14. This study indicates that Ap Ti provides the most favorable conditions for differentiation of bone marrow cells, and, at a later stage, AH Ti also provides favorable conditions, perhaps because of the formation of a surface layer of calcium phosphate. This potential for apatite formation may play an important role in osteoblastic differentiation.

Alkaline Phosphatase↗
PubMed2001

In vitro resorption of three apatite cements with osteoclasts.

To evaluate the replacement of apatite cement (AC) with bone, osteoclasts were incubated for 48 h on the surface of three AC types: conventional AC (c-AC), fast-setting AC (fs-AC), and anti-washout AC (aw-AC), using sintered apatite (AP) and cortical bone as control materials. We found osteoclasts attached to the surface of AC and osteoclastic resorption pits after 48 h of incubation for all experimental AC types. In contrast, no resorption pit was observed on the surface of sintered AP although osteoclasts were attached to the surface of sintered AP. There was no significant difference among the types of AC with respect to the resorption area, but the resorption areas were only approximately 1% of that on the surface of cortical bone. We concluded, therefore, that ACs could be replaced with bone regardless of the type but that it takes extensive time for the ACs to be completely replaced with bone.

Animals↗