Ceramics Biomaterials

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Ceramic Biomaterials

Transcript of Ceramics Biomaterials

  • 3. Ceramic biomaterials: contents 3.0 Ceramics

    (1) Definition

    (2) Characteristics

    3.1 Outline of ceramic biomaterials

    (1) Applications

    (2) Classification

    3.2 Ceramic biomaterials

    (1) Oxides

    (2) Glasses

    (3) Calcium phosphates 1

  • 3.0 Ceramics

    (1) Definition

    2

  • Definition

    Ceramics from keramos (the Greek word)

    the art and science of making and using solid

    articles formed by the action of heat on earthy raw

    materials

    the art and science of making and using solid articles

    which have as their essential component, and are

    composed in large part of, inorganic materials

    (Introduction to ceramics, 2nd edition, 1976)

    Inorganic and nonmetallic solid materials

    3

  • Ceramics

    metal-nonmetal compounds: TiC, Al2O3, ZrN, semi metal-nonmetal compounds: SiC, SiO2, BN, crystalline, non-crystalline oxide, carbide, nitride, boride, pottery, glass, refractory, cements, structural clay products , + new ceramics (fine ceramics)

    4

  • Fine ceramics

    According to ISO 20507: Fine ceramics (advanced ceramics,

    advanced technical ceramics) - Fine Ceramics are " highly

    engineered, high performance, predominantly non-metallic,

    inorganic, ceramic material having specific functional

    attributes".

    the 1980s: fine ceramics boom

    (magnetic, ferroelectronic, structural,,,)

    1986: High-temperature superconductor

    (La-Ba-Cu-O system)

    Improvement in processing and purity of ceramic source powders

    development of bioceramics 5

  • 3.0 Ceramics

    (2) Characteristics

    6

  • Characteristics of ceramics Chemical bonding: ionic and covalent bonding

    high melting point

    high hardness

    high chemical stability

    high elastic modulus

    high creep property

    low density

    low thermal expansion coefficient

    brittle poor workability sensitive to flaw

    Anisotropy in bonding direction

    7

  • Mechanical properties of ceramics

    (A. Nozue, Bull. Ceramic Soc. Jpn., 38 (2003), 21.)

    Materials Tensile strength (MPa)

    Bending strength (MPa)

    Compressive strength (MPa)

    Elastic modulus (GPa)

    Fatigue limit (MPa)

    Fracture toughness (MPa/m1/2)

    Cortical bone

    Cancellous bone

    Ti-6Al-4V alloy

    Co-Cr-Mo alloy

    Titanium

    Alumina

    Zirconia

    Hydroxyapatite

    8

  • 9

    Stress-strain curves

    Figure 1-1 Schematic illustration of stress-strain curves of biomaterials.

    , (2010), 191

  • Comparison with other biomaterials

    Materials Examples Advantages Disadvantages

    Metals

    Titanium and its alloys

    Co-Cr alloys

    Stainless steels

    Au, Ag, Pt

    Excellent balance of strength

    and ductility

    Shape memory effect

    Electrical conductivity

    Thermal conductivity

    May corrode

    High density

    Ceramics

    Alumina(Al2O3)

    Zirconia(ZrO2+oxide)

    Hydroxyapatite

    (Ca10(PO4)6(OH)2)

    Calcium phosphate

    Very biocompatible

    High strength

    High wear resistance

    Inert

    Brittle

    Not resilient

    Difficult to make

    Polymer

    Silicone

    Polymethylmethacrylate

    (PMMA)

    Polyethylene

    Easy to fabricate

    Low density

    Resilient

    Not strong

    Deforms with time

    May degrade

    Ceramics Wear resistance

    Chemical stability

    Biocompatibility with bone

    Table 1-3 Classification of biomaterials by structure and chemical bond.

    10

  • 3.1 Outline of ceramic biomaterials

    (1) Applications

    11

  • Applications

    Orthopedic () Dental () Coating () + Scaffold ()

    (Biomaterials Science, An Introduction to Materials in

    Medicine 2nd Ed. Elsevier, (2004), p.162.) 12

  • Ceramic biomaterials

    () ()

  • Orthopedic field: materials used in Japan

    Figure 2-1 Mass of biomaterials in orthopedic field in Japan. (T. Narushima, J. Jpn. Inst. Light Metals, 55 (2005), 561-565.) 14

  • stem

    ball

    cup

    backing

    Figure 3-1 Artificial hip joint. a: backing, b: cup, c: ball, d: stem

    Figure 3-2 Biomaterials used in artificial hip joint. (Biomedical Engineering Handbook, Vol.1 (2000), 44-16.)

    Orthopedic field: artificial hip joint Orthopedic load-bearing applications

    : alumina (Al2O3), zirconia

    15

  • Coating: artificial hip joint and dental implant

    Rapid and strong fixation at

    bone/titanium interface

    Coating for chemical bonding with bone

    (Ca10(PO4)6(OH)2, hydroxyapatite, HAp)

    (bioglass)

    artificial hip joint dental implant

    16

  • Coating: processing

    Currently, plasma spraying is the primary

    method used commercially to fabricate a

    calcium phosphate coating on dental implants.

    However, plasma-sprayed calcium phosphate

    coating exhibits a poor adherence to titanium

    substrates and nonuniformity.

    New coating

    processes

    17

  • Figure 3-3 Reconstruction of right calf bone

    using b-TCP(Ca3P2O8) porous body. (H. Irie, Bull. Ceramic Soc. Jpn., 38 (2003), 57.)

    Temporary bone space filler

    After 18 months

    b-TCP

    (Tricalcium phosphate,

    Ca3P2O8)

    Bioresorbable or

    biodegradable material

    The porous b-TCP body was

    substituted with bone.

    18

  • Parameters in scaffold materials

    Stability

    Resorption rate

    Bioactive molecules / ligands

    Soluble factors

    Strength

    Signaling

    molecule Scaffold

    Cell

    Three factors required for tissue engineering

    Porous calcium phosphate

    tissue

    engineering

    19

  • Figure 3-4 Hydroxyapatite porous body. (M. Nakasu et al., Bull. Ceramic Soc. Jpn., 40 (2005), 828.)

    Scaffold in tissue engineering

    The structure of a substrate

    made of synthetic materials

    is needed for the growth of a

    new tissue using living cells.

    20

  • 3.1 Outline of ceramic biomaterials

    (2) Classification

    21

  • Classification (1) From composition and crystalline structure

    of ceramic biomaterials

    Oxides alumina, zirconia,

    Glasses bioglass, crystallization glass,

    Calcium phosphates hydroxyapatite, tricalcium phosphate,

    In this lecture, we use the above classification.

    22

  • Classification (2) When materials are implanted into bone, there are four types of

    response at the interface between implant and bone.

    Capsule:

    bioinert

    Implantation

    Dead: toxic

    Dissolved:

    bioresorbable

    Bonding:

    bioactive

    Material

    bone

    Figure 3-5 Response at the interface between implant and bone. 23

  • Classification (2) When materials are implanted into bone, there are four types of

    response at the interface between implant and bone.

    material: toxic

    The surround tissue dies.

    not practical materials

    material: non-toxic and biologically inactive

    A fibrous tissue of variable thickness forms.

    Bioinert materials

    material: non-toxic and biologically active

    An interfacial bond forms.

    Bioactive materials

    material: non-toxic and dissolved

    The surrounding bone replaces it.

    Bioresorbable or Biodegradable materials

    24

  • Classification (2) When materials are implanted into bone, there are four types of

    response at the interface between implant and bone.

    25

  • 3.2 Ceramic biomaterials

    (1) Oxides

    26

  • Oxide: Alumina

    Alumina: Al2O3

    Excellent wear resistance

    Chemically stable

    ball for artificial hip joint

    27

  • Artificial hip joint

    28

  • Alumina: properties

    (Biomaterials Science, An Introduction to Materials in

    Medicine 2nd Ed. Elsevier, (2004), p.157.)

    Single crystalline

    alumina

    99.9

    3.95

    392

    1270

    2100

    0.01

    29

  • Oxide: zirconia

    Zirconia: ZrO2

    Pure zirconia (ZrO2): not an engineering material

    because

    There are two allotropic transformations.

    monoclinic tetragonal cubic

    At around 1400 K, t-m transformation causes

    4.6% volume change.

    30

  • Pure zirconia: properties

    (Biomaterials: An Introduction,

    Springer, (2007), p.145.)

    31

  • (T. Miyazaki, J. Jpn. Soc. Biomater., 25 (2007), 374.)

    Zirconia: transformation

    : Zr : O expansion

    monoclinic tetragonal cubic shrinkage

    Temperature

    32

  • Zirconia: stabilizing

    Fully stabilized

    zirconia

    Partially stabilized

    zirconia

    When oxide such as CaO,

    MgO or Y2O3 was added

    to pure zirconia, cubic and

    tetragonal phases are

    stabilized.

    33

  • Zirconia: properties

    (Biomaterials: An Introduction, Springer, (2007), p.147.)

    CSZ: calcia stabilized zirconia

    Y-Mg-PSZ: yttria and magnesia partially stabilized zirconia

    Y-TZP: yttria-stabilized tetragonal zirconia polycrystal

    Th