Ceramics Study Guide

Question 1

state two biomedical applications for ceramics

Answer 1

orthopedics-as coating on implants to help them from being rejected from the body. “hydroxyapatite may be used”

dentristry- orthodonics brackets

drug delivery systems

Question 2

what are the two most commonly used structural biocermaics

Answer 2

Alumina and zirconia

Question 3

what are the advantages of ceramics?

Answer 3

• inert in body (or bioactive in body) chemically many enviorments
• high wear resistance (orthopedic and dental applications)
• high modulus (stiffness) and compressive strength
• esthetic for dental applications

Question 4

what are the disadvantages of ceramics

Answer 4

brittle (low fracture resistance) low tensile strength, poor fatigue resistance

Question 5

define bioactivity as it relates to ceramics.

Answer 5

property that allows the material to directly bond with the host biological tissue

Question 6

what is true about bioactive ceramics?

Answer 6

• Composition includes SiO2, CaO and Na2O
• Bioactivity depends on the relative amounts of SiO2, CaO and Na2O
• Cannot be used for load bearing applications
• Ideal as bone cement filler and coating due to its biological activity

Question 7

what is not one of the four bone mimicry properties of calcium phospate

Answer 7

ductility

Question 8

what is the most stable form of calcium phospate?

Answer 8

crystalline hydroxyapatite

Question 9

name three uses of biodegradable ceramic-calcium phospate?

Answer 9

–drug-delivery
–repair material for bone damaged trauma or disease
–void filling after resection of bone tumors –repair and fusion of vertebrae
–repair of maxillofacial and dental defects

Question 10

Calcium ___ are the most common biodegradable ceramics.

Answer 10

phospates

Question 11

list four physical properties of cermaics

Answer 11

• Highly inert; thus, biocompatible. 
• Hard and brittle
 • Wear resistant
 • Good aesthetic appearance
-brittle

Question 12

list three examples of ceramics used for biomedical application

Answer 12

• alumina and zirconia used as modular heads on femoral stem hip components. They have less wear.
• alumina used for othopedic implants
• alumina used in dental implants

zirconia- dental crowns and bridges

-calcium phospate- drug delivery

-

Question 13

elaborate on a method used for processing of ceramics

Answer 13

compounding- mix and homogenize ingredients into a water based suspension=slurry or, into a solid plastic material containing water called clay

forming- the clay or slurry is made into parts by pressing into mold particulate are fine grained crystals

drying-the formed object is dried, usually at room termperature to the so called “green’ or leathery state

firing-heat in furnace to drive of remaining water. May produce shrinkage….Porous parts are formed by adding a second phases that decomposes at higher temperatures forming the porous structures

Question 14

state the various possible ceramic-implant tissue response

Answer 14

if the material is toxic- the surrounding tissue dies

if material is nontoxic and biologically inactive- a fibrous tissue of variable thickness forms

if the material is nontoxic and biologically active an interfacial bond forms

if the material is nontoxic and disolves-the surrounding tissue replaces it

Question 15

describe the classificiation of ceramics based on its chemical reactivity in the body environment

Answer 15

completely resorable-most reactive promotes cell growth. complete degrades

surface reactive-exhibit intermediate behavior.surface provides bonding sites for tissues prodducing tissue adherence.

nearly inert- little chemical reactivity and show minimal interfacial bonds with living tissues

Question 16

name an intert cermaic and state on of its biomedical application

Answer 16

Alumina= used one femoral head of hip stem
knee prosthesis

dental crowns and bridges

Question 17

State two dental applications for ceramics

Answer 17

dental crowns and bridges, orthodonics brackets

Question 18

give an example of carbon based biomaterial and state its biomedical application

Answer 18

pyrolitic carbon-coated devices with blood have resulted in extensive use in heart valves

Question 19

give two examples of the availability of bioceramic in different physical forms

Answer 19

• microspheres
• thin layers or coatindescgs on a metallic implant
• pourous networks
• composites with a polymer component
• large well polished surfaces

Question 20

describe the four classification of ceramics based on tissue attachment

Answer 20

Type 1: Dense, inert, nonporous ceramics. Attach bone by tissue growth into surface irregularities OR by press fitting (termed as morphological fixation)

Type 2: Porous inert ceramics attach by bone ingrowth into pores resulting in mechanical attachment of bone to material (termed as biological fixation)

• Type 3: Dense, nonporous surface-reactive ceramics attach directly by chemical bonding with bone (termed as bioactive fixation)
• Type 4: Dense, nonporous (or porous) resorbable ceramics which are slowly resorbed and replaced by bone

Question 21

what is a pyrolytic carbon?

Answer 21

is a man-made carbon…. and not found in nature.It is a material very similar to graphite. it exhibits excellent biocompatibility with tissue.