Upgrade to remove ads
Only $35.99/year

Bioceramics

Terms in this set (78)

Bioceramics are ceramic materials that are specially developed for...
use as medical and dental implants
Examples of bioceramics include (7)...
- alumina
-zirconia
-bioactive glass and glass-ceramics
-composites
-hydroxyaphite
-resorbable calcium phosphastes (RCP)
-radiotherapy glasses
6 Clinical applications of bioceramics
1. Orthopedics (MAJORITY USE)
2. Otolaryngology
3. Maxillo-facial and plastic surgery
4. Oral surgery
5. Periodontology
6. Tumor therapy
Ceramic is becoming increasingly useful in...
the medical world
Ceramic applications in orthopedics inlcude...
- arthroplasties
- for hip, knee, shoulders, elbows, fingers, and wrists
Ceramic applications in cardiovascular include...
total heart valve replacements
Ceramic applications in dentistry include...
- tooth replacement implants (containing fluorapatite and small particles of glass is being used to replace teeth)
- braces
Research is even being done on a "ceramic" based...
gum which is thought to retard the growth of plaque
Benefits of ceramics in implants include(4)...
- coatings to metal replacements
- stimulate bone growth
-promote tissue formation
- provide protection from the immune system
Glass microspheres smaller than a human hair deliver...
large, localized amounts of radiation to diseased organs in the body
Ceramic is one of the few materials durable and stable enough to withstand...
the corrosive effects of bodily fluids
Ceramics are used in surgery as...
form of ceramic coated scissors
*Ceramic coatings have a surface hardness four to five times greater than...
that of stainless steel
Ceramic coatings provide higher....
sliding capacity to reduce abrasion
A good mechanical property of Ceramic coatings is that they optimize...
resistance to rust and corrosion (which is important in biomedical applications)
Ceramic-coated hip and knee implant systems were designed to increase ______ and reduce _______
increase resistance and reduce wear of implant components
Endoprosthesis (implants/TJR) are coated with an innovative thin layer of ceramic to....
significantly reduce wear and deterioration
What is known to be the major cause for implant failure?
- wear of polyethylene
Ceramic coating is added to give __________ and ___________ articulations optimal resistance against wear
metal-to-metal and metal-to-polyethylene
Articulating surfaces of endoprosthesis is coated with a...
TiN (Titanium Nitrate ceramic)
The Titanium nitrate ceramic is harder up to...and smoother....
600% than the Cobalt Chromium substrate ; resulting in lower wear of the implant
Milky white color on implant usually indicates...
use of ceramic
Ceramics fulfill a unique function as...
biomedical materials
Ceramics can fall into all three biomaterial classifications which are...(include their meaning)
1. Inert (can remain unchanged)
2. Resorbable (can dissolve)
3. Active (can actively take part in physiological processes)
Ceramics satisfy needs as diverse, low-coefficient of friction for lubricating...
surfaces in joint prosthesis and surfaces on heart valves that avoid blood clotting
Blood clotting occurs when...
blood stops moving
Ceramic materials help to....
stimulate bone growth and harness radioactive material for therapeutic treatments
Wear is common to occur in joint replacements because lack of...
synovial fluid to prevent rubbing and friction
Materials that can be classified as bioceramics (5)
1. Alumina
2. Zirconia
3. Calcium phosphates
4. Silica based glasses or glass-ceramics
5. Pyrolytic carbons
Bioceramics are available as (5)....
1. Micro-spheres
2. Thin layers or coatings on metallic implant
3. Porous networks
4. Composites with a polymer component
5. Large well-polished surfaces
Bioceramics are ceramics used in biomedical applications ranging from...
medical implants to biomedical pumps
Example of bioceramics in medicine is...
Y-TZP Endoscopes (endoscopic components)
Alumina and Zirconia are known for their general chemical...
inertness and hardness
Alumina and Zirconia are used for...
- implant/TJR purposes
- articulating surface in hip and knee joints
Alumina and Zirconia have the ability to be polished...
to a high surface finish
This ability to have a high surface finish makes Alumina and Zirconia an ideal candidate for...
the wear application because they can operate against materials TJR's menisci [ultra high molecular weight polyethylene (UHMWPE)]
Porous alumina is used as...
a bone spacer and a scaffold for bone ingrowth
Single crystal alumina is used in...
dental applications (implants and braces)
Advantage of porous ceramics is that it can be used in...and its...
implants ; inertness
Mechanical stability of porous ceramics
- highly convoluted interface allow bone/tissue to grow and attach into pores
The pores for porous ceramics are greater than...
100 micrometers
The pores must be this size for...
- bone/tissue to grow within the inner connecting pore channels near the surface
- maintain vascular supply and vitality of bonding
Commercial porous products include....
Hydroxyapatite (HA) derived from Coral and animal bones
Porous materials exhibit a _____ mechanical strength compared to the equivalent bulk form and is proportion to the percentage of porosity
weaker
As porosity increases, the strength of material...
decreases rapidly (ex. cortical bone is stronger than spongy cancellous bone)
Bioactive ceramics will....
attach/bond to bone
Bioactive glasses will....
attach/bond to bone and soft tissue
Bioactive material (bioactive glasses) develop an adherent interface with tissues and resists....
substantial mechanical forces
The process of bonding to bones in implantation was first accomplished from a compositional range of bioactive glasses that contained...
SiO2 , Na2O , CaO , and P2O5 in specific proportions
The two-phase silica-phosphate glass-ceramic is composed of...
- Apatite [Ca10(PO4)6(OH)1F2]
- Wollastonite crystal [CaO , SiO2]
- a residual silica glassy matrix termed A-W glass ceramic (A-WGC)
If additional amounts of Al2O3 or TiO2 is added to the A-W glass ceramic it will also....
inhibit bone bonding
The multiphase bioactive Phosphosilicate is composed of...
- Phlogopite (Na, K)- Mg3[AlSi3O10]F2
- Apatite crystals, which can bond to bone even though Al is present in the composition
Al3+ ions are incorporated within the crystal phase and do not...
change the surface reaction kinetics of the material
Stages of Surface Reaction
1 & 2. Formation of SiOH bonds and release of Si(OH)4
3. Polycondensation of SiOH + SiOH --> Si-O-Si to form hydrated silica gel
4. Absorption of amorphous Ca + PO4 + CO3
5. Crystallization of hydroxyl carbonate apatite (HCA)
6. Absorption of biological moieties in HCA layer
7. Action of macrophages
8. Attachment of osteoblast stem cells
9. Differentiation and proliferation of osteoblasts
10. generation of matrix
11. Crystallization of matrix and growth of bone
The failure strength of bioactively fixed bond is ....
inversely dependent on the thickness of the bonding zone
Interfacial strength is a function of such morphological factors as the...
change in interfacial tissues with time
Interfacial strength results in an increase in the elastic modulus of the interfacial bond as well as...
shear strength per unit of bonded area
Healed cortical bone has an internal bond strength of about...
30 MPa
Look at graph in notes on interfacial bond strength
Have to know the graph!!
Composition of bone by weight
- 25% water
- 15% organic material
- 60% mineral phases : Ca, P ions, and traces of Mg, carbonate, Hydroxyl, Chloride, & Fluoride
The main crystalline component of the mineral phase of bone is a...
calcium carbonate Hydroxyapatite (HA)
The process and condition in which synthetic HA is made will...
affect/influence its mechanical and chemical properties
Factors that affect the rate or resorption of the implants
1. Physical factors
2. Chemical factors
3. Biological factors
Physical factors that affect rate of resorption include...
surface area and crystal size
Chemical factors that affect rate of resorption include...
atomic and ionic substitution in the lattice
Biological factors affect the rate of resorption include...
types of cells surrounding the implant and location, AGE, species, sex and hormone levels
Presently, X-ray diffraction and infra-red spectroscopy are used to...
reveal the phase purity and level of hydroxylation of HA
Dehydration of HA results in the formation of....
Oxyhydroxyapatite Ca10(PO4)6(OH)2 - 2xOxVx (V is hydroxyl vacancy)
In clinical applications, calcium phosphate ceramic is largely limited to...
non-major-load bearing parts of the skeleton due to its inferior mechanical properties
Therefore, calcium phosphate is used in coatings on...
metallic implant substrates
Calcium phosphate ceramics strongly influence their application as...
implants because of their mechanical properties
Tensile, compressive, and fatigue resistance depend on the...
total volume of porosity
When porosity is <1 micrometer and >100 micrometer....
a) <1 micrometer in diameter: due to incomplete sintering (cooling down)
b) >100 micrometer in diameter: created to permit bone growth
The Hydroxyapatite's (HA) lattice contains two kinds of calcium phosphates which are...
1. Columnar
2. Hexagonal
The HA may be processed as ceramic using compaction....
- die pressing
- isostatic pressing
- slip ad casting
- followed by solid-state sintering
Biodegradation and resorption of calcium phosphate ceramics is caused by 3 factors
1. Physiochemical dissolution, which depends on the solubility product of the material and local pH of its environment
2. Physical disintegration into small particles as a result of preferential chemical attack of grain boundaries
3. Biological factor: phagocytosis, which causes a decrease in pH concentrations
Biodegradation increases as (5)...
1. Surface area increases
2. Crystalline decreases
3. Crystal perfection decreases
4. Crystal and grain size decreases
5. There are ionic substitutions of CO2-3, Mg2+, & SR2+ in HA
Factors that tend to decrease rate of biodegradation (3)
1. F-substitution in HA
2. Mg2+ substitution in Beta-TCP
3. Lower beta-TCP/HA ratios in biphasic calcium phosphates
Recommended textbook explanations

Fundamentals of Electric Circuits

6th EditionCharles Alexander, Matthew Sadiku
2,102 explanations

Engineering Mechanics: Statics

14th EditionR.C. Hibbeler
1,437 explanations

Thermodynamics: An Engineering Approach

9th EditionYunus A. Cengel
2,611 explanations

Materials Science and Engineering: An Introduction

9th EditionDavid G. Rethwisch, William D. Callister
1,115 explanations