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10 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Local factors influencing osseointegration?
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Materials
Heat Contamination Surface composition and structure Initial stability Bone quality Epithelial down growth Early loading Late loading |
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Features of implant body which enhance osseointegration?
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screw threads
macro surface irregularities porous metallic and ceramic coatings |
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Material surfaces should be considered special states of matter with unique chemistry organisation, dynamics and electrical properties. The major differences between surface and bulk structures arise from...?
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1. the direct accessibility of surface molecules for reaction with adjacent phases
2. the tendency for Surface energy of minimization to reach equilibrium as mediated by re-arrangement of chemical groups, additive migration and spontaneous adsorption |
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What are positive tissue reactions?
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contact
connection growth differentiation |
CoCoGrDi
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What are negative tissue reactions?
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Rejection
Encapsulation Thrombogenesis Ectopic calcification Resorption |
(RETER)
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Chemical composition of the material surface influence which factors?
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Early responses of the biologic environment
Controls the hydrophilic or hydrophobic character Energy state of surface |
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Surface thermal mobility is found in which materials?
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Materials with very low elastic modulus
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Implant material classifications, compositions and bone responses
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Biotolerant: CoCrMo, PtAu, Polymers: distant osseointegration and connective tissue interface
Bioinert: Ti Ta, Alumina, Zirconia, Ceramics: Close contact between bone and implant Bioactive: Ca-P Ceramic, Bioglass and bioceramic: Bonding osseointegration (Chemical bond) |
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Describe the osseointegration process
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Immediately after implantation
At the outer oxide layer: 1. selective adsorption of H2O, O2-, PO4-, HPO4- ions 2. release of Ti as Ti(OH)4 At the interface: TiO2 layer forms rich in TiHPO4 Increase in thickness Increase in crystalinity and solubility of oxide film With time: Precipitation of CaPO4 >> formation of complex of CaPO4 and TiPO4 Further adsoprtions influenced by: 1. activation of PMN and macrophages 2. decrease in pH at exudating stage 3. release of proteins, enzymes and oxidising agents Inflammatory cells secrete oxygen intermediates which form TiPeroxy compounds which reduce inflammation |
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What are the effects of the coating and what are the pitfalls?
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Modify tissue response near the implant
Accelerate bone attachment Increase osteoblast precursor activity causing increased extracellular matrix mineralisation Pitfalls: bone resorption cohesive fracture debonding of ceramic coating |
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