High temperature behaviour of hydroxy‐ and fluorapatite

Newesely, H

doi:10.1111/j.1365-2842.1977.tb00971.x

Cited by 42 publications

(16 citation statements)

References 7 publications

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“…24,25,28 A reason for this might be the longitudinal sectioning of the implants used in this experiment, which could give a more complete histological overview and demonstrate the bone-growth effect more clearly than the transverse sections used in other experiments. 24,28 Some reports 24,25,28 used only one or two transverse histological sections per implant, thereby excluding the ability to observe the described pattern of bone formation reported herein. Although a model without spacers would be preferable, a standardized and reproducible gap size is an important prerequisite for this experiment, which necessitated the use of the spacers.…”

Section: Discussionmentioning

confidence: 99%

“…24,25 This material, fluorapatite (FA), therefore will be less affected by the plasma-spray process and will maintain its highly crystalline character, resulting in reduced solubility. 18,19,22,24,25 It is known from in vivo studies that FA, compared to HA, demonstrates an equal degree of bone apposition and less coating dissolution within the first 3 months after implantation. [26][27][28] Thus FA coatings could be a promising alternative to HA coatings.…”

Section: Introductionmentioning

confidence: 99%

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Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Clemens

Klein

Sakkers

et al. 1997

J. Biomed. Mater. Res.

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Hydroxylapatite coatings are under clinical investigation in orthopaedics and dentistry. Bone formation on apatite coatings in the presence of gaps is important for clinical applications. The importance of the stability of the coating is not known at present. By varying the plasma-spray parameters, and by the addition of fluoride, the crystallinity and stability of calcium phosphates can be changed. It is suggested that bone formation is enhanced by dissolution of the apatite coating. We studied apatite coatings of varying stability with regard to their gap-healing characteristics, and we examined what the maximum gap would be that can be bridged if a coating is applied. Ti-6A1-4V implants coated with 62% crystalline hydroxylapatite, 30% crystalline hydroxylapatite or fluorapatite, or noncoated Ti-6A1-4V were implanted in 16 goats. The implants were surrounded by gaps of 1 or 2 mm, and the follow-up period was 6 weeks. Histological examination and histometry revealed that gaps of 1 mm can be bridged by bone if an apatite coating is applied. However, only a minimal amount of bone contact was seen on the apatite coatings with 2 mm gaps. Uncoated implants demonstrated no bone contact at all. Among the three different coatings there were no differences in gap healing. It can be concluded that in the goat, gaps of 2 or more mm between coated implants and host bone tissue inhibit bone deposition on the coating (p < 0.05), but the stability of the coating does not influence gap-healing characteristics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Clemens

Klein

Sakkers

et al. 1997

J. Biomed. Mater. Res.

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“…The synthetic compound could be successfully sintered by CO 2 laser to the dental enamel with minimal thermal effect. The medium energy laser, according to the SEM study, had biological safety less than 8008C and the HA compound could be sintered in a short period of irradiation [6].…”

Section: Discussionmentioning

confidence: 99%

“…Hydroxyapatite disproportionates into a mixture of a-tricalcium phosphate and tetracalcium phosphate on heating at about 1,4508C [6] in air and the mixture melts at about 1,6008C [7,8].…”

Section: Introductionmentioning

confidence: 99%

Sintering mechanism of the CaF₂ on hydroxyapatite by a 10.6‐lμm CO₂ laser

Wu¹,

Roan²,

Chen³

2002

Lasers Surg Med

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In this study, we proposed the interrelationship of the eutectics between initiator (CaF(2)) and the reaction product (calcium hydroxide) that reduced the sintering temperature. It appeared that the co-eutectics interacted to reduce the sintering temperature of hydroxyapatite below 800 degrees C and that the key eutectic was calcium hydroxide. The clinical feasibility of the melting and re-crystallization of hydroxyapatite under 10.6-microm CO(2) laser would be therefore enhanced.

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“…of the disproportionation products. Human tooth enamel melts above 1,280~ [29]; HA disproportionates into a mixture of o~-TCP and TETCP on heating at about 1,450~ in air [30] and this mixture melts at about 1,600~ [31].…”

Section: Discussionmentioning

confidence: 99%

Compositional, structural, and phase changes inin vitro laser-irradiated human tooth enamel

1984

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Tooth enamel laser irradiated under certain conditions previously has been shown to have reduced subsurface demineralization rates. Identification of these laser-induced changes has bearing on understanding the dissolution rate reduction mechanism; some of these changes, ones that occur in high temperature regions, were studied in this report. X-ray diffraction and infrared spectroscopy were used to identify changes in enamel of extracted intact human teeth subjected to high energy density (approximately 10,000 J/cm2) 10.6 microns wavelength carbon dioxide laser irradiance. The laser irradiance melted the enamel apatite; this solidified melt was composed of minor phases of alpha-tricalcium phosphate, alpha-Ca3 (PO4)2, and tetracalcium phosphate, Ca4(PO4)2O, and a major phase of modified apatite. The apatite modifications, as compared with the original were (1) reductions in contents of water, protein, carbonate, and chloride (or chloride rearrangement); (2) essentially no change in apatite hydroxide content; (3) possible incorporation of oxide replacing some hydroxide ions; and (4) an uptake of traces of carbon dioxide and cyanate. An infrared band at 434 cm-1 that appears in spectra of hydroxyapatite partially dehydroxylated by thermal treatment was assigned to oxide translation. This band was utilized to search for oxide formation in the laser-irradiated tooth enamel.

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High temperature behaviour of hydroxy‐ and fluorapatite

Cited by 42 publications

References 7 publications

Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Sintering mechanism of the CaF₂ on hydroxyapatite by a 10.6‐lμm CO₂ laser

Compositional, structural, and phase changes inin vitro laser-irradiated human tooth enamel

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High temperature behaviour of hydroxy‐ and fluorapatite

Cited by 42 publications

References 7 publications

Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Healing of gaps around calcium phosphate-coated implants in trabecular bone of the goat

Sintering mechanism of the CaF2 on hydroxyapatite by a 10.6‐lμm CO2 laser

Compositional, structural, and phase changes inin vitro laser-irradiated human tooth enamel

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Sintering mechanism of the CaF₂ on hydroxyapatite by a 10.6‐lμm CO₂ laser