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level: Level 1

Questions and Answers List

level questions: Level 1

Question	Answer
inorganic, non-metallic compounds; high melting point, chemical resistance, brittle, high strength, high modulus, wear resistance	Ceramics and name 3 properties
Crystalline, Glass, and Glass-ceramic	Main types of Ceramics
BCC, FCC, Hexagnal	Most common crystalline structures
inert, non-allergic, long life time, temp. resistance, non-carcinogenic Alumina, Zirconia, Calcium Phosphates (HAP)	Desired properties of Implantable Bio-ceramics (name 3) and examples
wear resistance, long life time, mostly used in dental implants	Alumina properties
relatively flexible, tough, low modulus, strong (stress shielding)	Zirconia properties
good mechanical properties, osteoinductive	HAP (Hydroxyapatite) properties
Measuring crystallinity of a material, crystalline peaks and amorphous humps	XRD is used for?
Slurry of ceramic material, to stabilize fractures, injected with low exothermic reaction during hardening and sets at the appropriate time	Bone Cements (what, why, how?)
To material surfaces coming together and staying intact	Cohesion is?
implantable solid particles that can be resorbed and stabilize a fracture example: JAX or Osteoset	Bone Void Fillers are?
material can uptake payload, material can hold on to payload as directed/needed, payload is delivered properly. Drugs to be delivered are antibiotics, anti-inflammatories, hormones, etc.	Drug Delivery basics
Form apatite layer and is good as a bone filler	Bioactive Glass can?
semi-crystalline, devitrification (resistant to thermal shock, increased toughness)	Glass-Ceramics properties
hard, shiny, malleable, fusible, and ductile material with good electrical and thermal properties. Crystalline solid with an electron cloud. -grain boundaries and dislocations: created in processing and determine properties -Alloying controls properties	Metals and its properties
1. Get metal (found in ore): ore separation (smelting, chemical, water flow) 2.Prepare raw material: casting (forging, CAD, investment, powdering processing 3. Surface Treatment: adding porosity (plasma spray) 4. Packaging: polishing, cleaning, sterilize, etc.	Process of Obtaining Metal
Abrasion- harder surface dents softer Adhesion- soft surface smears on harder Fatigue- repeated alternate loading (cyclic)	Mechanisms of wear
is oxidation; Galvanic- two metals with different inertness Passivation-layer that forms to protect metal from corroding Pitting- localized corrosion, picks at passivating layer Crevice- two surfaces meet Cracking promotes corrosion (failure)	Corrosion
wear + corrosion cracks + corrosion	Fretting
wear resistance, patient comfort, longevity, corrosive resistant, carry the load (cyclic and monotonic)	Implant Requirements
pros: ductile, tough cons: can have nickel allergies, limited wear resistance, limited strength	Stainless Steel pros and cons
pros: strength, ductility, toughness, corrosion resistance cons: not very wear resistance, can have nickel allergies	cobalt-chromium alloys pros and cons
pros: passivating layer, ductile, strong cons: higher chance of stress shielding	Titanium alloys pros and cons
workable and moldable, great for crowns or cusps, super biocompatible	Gold
a group of repeated mer units forming a long chain. unique materials, very large molecules cause chain entanglement and influence properties	Polymers
cross-linked polymers that cannot be melted	Thermoset
meltable plastics, can recyclable	Thermoplastic
stretch, but return	Elastomers
unsaturated-double or triple bond between carbons saturated- all bonds are single	Hydrocarbon molecules
Initiation: R-active initiator w/ loose electron Propagation: bonds with electron (longer chains) Termination-I: active ends of two chains come together Termination-II: single activator ends line	Polymerization
monomers come together w/ water or hydrochloric acid	Condensation Polymerization
polyolefins - made w/ alkene monomers polyesters, amindes, urethanes - made with whose function groups natural - polysaccharides, proteins, DNA, rubber, cellulose	Polymer families
1. random 2. alternating 3. block 4. graft	types of copolymers
1. linear 2. branched 3. cross-linked 4. network	The polymer arrangements
Different conformations through rotation of valance bonds Isotactic, Syndiotactic, Atactic	Tacticity and types
Glass transition temperature, when above polymer becomes hard like glass when below they are more elastic and flow	Glass Transition
Fillers Plasticizers (make flexible and ductile) Stabilizers (protect against UV or oxidation) Colorants and Flame retardants	Types of Polymer processing
1.Compression molding 2.Injection molding 3.Extrusion (good for rods) 4.Blow molding (good for hollows)	Fabrication of Polymers
tough, long lasting, semi-crystalline, won't melt in body temperature wear occurs from repetitive motion, particles released cause macrophage activity	UHMWPE
semi-crystalline, high tensile strength, forms well, chemically stable	PEEK
breakdown or removal of a material in a body Polymers will decrease molecular weight, strength, and mass	Degradation
Hydrophilic - water breaks down polymer all at once with diffusion	Bulk degradation
Hydrophobic- polymer breaks down faster than water diffusion, like peeling an onion	Surface Erosion
Hydrolysis - cleavage of molecules, most common way Enzymatic - catalyzed by enzymes	Mechanisms of Degradation
with 1:1 ratio: lower modulus, bulk degrades (acidic) decreased ratio: higher modulus, short degrade time, FDA approved	PLGA
polymers that change in presence of a stimulus Ex: pH, temperature, etc. Types of changes: phase, shape, degrade, etc.	Smart Polymers
Material made with two or more other materials Can be same material different forms, Can be different materials	Composites
A hierarchical Composite (multiple composite organizations are different scales	Bone as a composite
1. Fiber 2. Particle 3. Laminar (layers) 4. Flake 5. Filled (porous filled with matrix)	Composite Organization
concentration, size, shape, orientation, distribution	Considerations
material in parallel w/ load axis, so strains are equal	Isostrain
material are perpendicular with load axis, so stresses are equal	Isostress
materials come apart, no more adhesion between layers, try to keep layers perpendicular to cracks	Delamination
Tortuosity, reinforced sections stop failing	Crack Deflection
crack would need to use a long of energy to continue (unfavorable)	Reinforcement cracking
Fiber spans crack, fiber pullouts also happen (helps prevent continuation of crack)	Fiber Bridging
Dental composites: better looks, mechanical properties, particle organization, crack deflection	Alumina- Glass
self-nuetralizing	PPHOS-PLGA
Hip implant: state of the art Cobalt-chrome core surrounded by PEEK shell and a titanium mesh. no stress shielding, mesh promotes bone growth for better fixation and load transfer	EPOCH
fill bone defects: types: autografts, allografts, bone scaffolds	Bone Grafts
taken from one site of patient to use at enough pros: biocompatible, osteoinductive. cons: limited supply, donor-site morbidity	autografts
taken from donor pros: no limit, no morbidity cons: sterilize (may change mechanics), less osteoinductive, disease transmission	allografts
a material used as bone graft pros: good strength, tough, degradable, osteo inductive, and biocompatible cons: PLGA has limited osteoinductiveness, Calcium Phosphate can be brittle and difficult to form	bone scaffolds
increases stiffness, strength, creep resistance allows thinner sections can replace metals PEEK- OPTIMA carbon compounds: x-ray and MRI compatible,	Carbon fiber composites