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Enhancing material and biological properties of calcium phosphate bone substitute

Camire, Christopher LU (2005)
Abstract
Calcium phosphate materials (CaPs) have proven biocompatible and useful in clinical situations. One CaP showing promise in the clinic is alpha phase tricalcium phosphate ([alpha]-TCP). [alpha]-TCP in powder form can be hydrated and undergoes a reaction resulting in calcium deficient hydroxyapatite (CDHA). The similarity of CDHA and human bone makes [alpha]-TCP a very viable material for application in bone defect. Studies were carried out investigating methods to enhance material and biological properties of calcium phosphate bone substitutes. Hydration reaction, reaction completion, and strength characteristics were studied, as well as effects of particle size on the reactivity of such compounds. Reactivity with relation to material... (More)
Calcium phosphate materials (CaPs) have proven biocompatible and useful in clinical situations. One CaP showing promise in the clinic is alpha phase tricalcium phosphate ([alpha]-TCP). [alpha]-TCP in powder form can be hydrated and undergoes a reaction resulting in calcium deficient hydroxyapatite (CDHA). The similarity of CDHA and human bone makes [alpha]-TCP a very viable material for application in bone defect. Studies were carried out investigating methods to enhance material and biological properties of calcium phosphate bone substitutes. Hydration reaction, reaction completion, and strength characteristics were studied, as well as effects of particle size on the reactivity of such compounds. Reactivity with relation to material crystallite size was further studied. X-ray amorphous fraction of powders and crystallite size was then investigated with relation to the speed of strength development. Addition of silicon to the [alpha]-TCP matrix was also examined. A silicon doped [alpha]-TCP was achieved which yielded promising results of increased osteoblastic activity both in vitro and in vivo.



It was seen with proper milling procedure that it was possible to prepare an [alpha]-TCP powder by solid state reaction that was potentially similar to one prepared using precipitation technique and that during hydration most of the strength developed during later stages of reaction. Surface area of the [alpha]-TCP has a significant impact on the reactivity however according to calculations, is not an accurate measure of degree of reaction. During high energy milling crystallite size is altered which has significant relation to thermal events during hydration as well as speed of reaction. The time needed to achieve maximum strength of hydrated [alpha]-TCP compounds appeared to relate to final CDHA crystal size and implied existence of a threshold of super-saturation needed to form CDHA at an accelerated rate. The [alpha]-TCP lattice was able to incorporate silicon and the in vitro and in vivo reactivity of the silica doped [alpha]-TCP was significantly increased upon testing in a bone harvest chamber rabbit model. CaPs as materials in the clinic are note only versatile, with the possibility of injectability, but can be adjusted in many ways to fit the desired application. (Less)
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author
supervisor
opponent
  • Professor, BSc, PhD de Bruijn, Joost, Queen Mary, University of London
organization
publishing date
type
Thesis
publication status
published
subject
keywords
materialteknik, Non-metallic mineral technology, Icke-metallisk mineralteknik, Biotechnology, Bioteknik, Materiallära, Material technology, Technological sciences, Teknik, Naturvetenskap, reumatologi, Surgery, orthopaedics, traumatology, Kirurgi, ortopedi, traumatologi, Natural science, muskelsystem, Skelett, muscle system, rheumatology locomotion, Bone Substitute, Calcium Phosphate, Skeleton, Medicin (människa och djur), Medicine (human and vertebrates), Osteoconductivity, Silicon, Mechanical Properties, Crystallinity, Reactivity, Calorimetry, Hydroxyapatite
pages
84 pages
publisher
Department of Orthopaedics, Lund University
defense location
Lecture Hall F1, Lund University Hospital
defense date
2005-09-22 13:15
ISSN
1652-8220
ISBN
91-85439-64-9
language
English
LU publication?
yes
id
4bc039a3-3861-4d4d-81d7-3e0ee32c2610 (old id 545247)
date added to LUP
2007-09-10 12:45:51
date last changed
2016-09-19 08:44:53
@phdthesis{4bc039a3-3861-4d4d-81d7-3e0ee32c2610,
  abstract     = {Calcium phosphate materials (CaPs) have proven biocompatible and useful in clinical situations. One CaP showing promise in the clinic is alpha phase tricalcium phosphate ([alpha]-TCP). [alpha]-TCP in powder form can be hydrated and undergoes a reaction resulting in calcium deficient hydroxyapatite (CDHA). The similarity of CDHA and human bone makes [alpha]-TCP a very viable material for application in bone defect. Studies were carried out investigating methods to enhance material and biological properties of calcium phosphate bone substitutes. Hydration reaction, reaction completion, and strength characteristics were studied, as well as effects of particle size on the reactivity of such compounds. Reactivity with relation to material crystallite size was further studied. X-ray amorphous fraction of powders and crystallite size was then investigated with relation to the speed of strength development. Addition of silicon to the [alpha]-TCP matrix was also examined. A silicon doped [alpha]-TCP was achieved which yielded promising results of increased osteoblastic activity both in vitro and in vivo.<br/><br>
<br/><br>
It was seen with proper milling procedure that it was possible to prepare an [alpha]-TCP powder by solid state reaction that was potentially similar to one prepared using precipitation technique and that during hydration most of the strength developed during later stages of reaction. Surface area of the [alpha]-TCP has a significant impact on the reactivity however according to calculations, is not an accurate measure of degree of reaction. During high energy milling crystallite size is altered which has significant relation to thermal events during hydration as well as speed of reaction. The time needed to achieve maximum strength of hydrated [alpha]-TCP compounds appeared to relate to final CDHA crystal size and implied existence of a threshold of super-saturation needed to form CDHA at an accelerated rate. The [alpha]-TCP lattice was able to incorporate silicon and the in vitro and in vivo reactivity of the silica doped [alpha]-TCP was significantly increased upon testing in a bone harvest chamber rabbit model. CaPs as materials in the clinic are note only versatile, with the possibility of injectability, but can be adjusted in many ways to fit the desired application.},
  author       = {Camire, Christopher},
  isbn         = {91-85439-64-9},
  issn         = {1652-8220},
  keyword      = {materialteknik,Non-metallic mineral technology,Icke-metallisk mineralteknik,Biotechnology,Bioteknik,Materiallära,Material technology,Technological sciences,Teknik,Naturvetenskap,reumatologi,Surgery,orthopaedics,traumatology,Kirurgi,ortopedi,traumatologi,Natural science,muskelsystem,Skelett,muscle system,rheumatology locomotion,Bone Substitute,Calcium Phosphate,Skeleton,Medicin (människa och djur),Medicine (human and vertebrates),Osteoconductivity,Silicon,Mechanical Properties,Crystallinity,Reactivity,Calorimetry,Hydroxyapatite},
  language     = {eng},
  pages        = {84},
  publisher    = {Department of Orthopaedics, Lund University},
  school       = {Lund University},
  title        = {Enhancing material and biological properties of calcium phosphate bone substitute},
  year         = {2005},
}