Ceramic Biomaterials (Bioceramics)

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Ceramic Biomaterials (Bioceramics)

• The class of ceramics used for repair and
  replacement of diseased and damaged parts of the
  musculoskeletal system are referred to as
  bioceramics.
• OBJECTIVES
• to examine chemical/physical properties of
  ceramics
• to introduce the use of ceramics as biomaterials

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Ceramics

• (keramikos- pottery in Greek)
• Ceramics are refractory polycrystalline compounds
• Usually inorganic
• Highly inert
• Hard and brittle
• High compressive strength
• Generally good electric and thermal insulators
• Good aesthetic appearance

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Structure

• Ceramic Structure AmXn

ZnS
A metal, ve
CsCl
NaCl
X nonmetal, -ve
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Types of Ceramics
nearly bioinert
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Inert Ceramics Aluminum Oxides (Alumina)

• Applications
• orthopaedics
• femoral head
• bone screws and plates
• porous coatings for femoral stems
• porous spacers (specifically in revision surgery)
• knee prosthesis
• dental crowns and bridges

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Alumina

• Inertness
• advantage is that it makes material more
  biocompatible
• disadvantage
• nonadherent fibrous membrane at the interface.
• interfacial failure can occur, leading to implant
  loosening

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Inert Ceramics Zirconia, ZrO2

• zirconium named from the Arabic, zargun gold
  color
• Fabrication
• Obtained from the mineral zircon
• Addition of MgO, CaO, CeO, or Y2O3 stabilize
  tetragonal crystal structure (e.g. 97 molZrO2
  and 3 molY2O3)
• Usually hot-pressed or hot isostatically pressed
• Applications
• orthopaedics femoral head, artificial knee, bone
  screws and plates, favored over UHMWPE due to
  superior wear resistance
• dental crowns and bridges

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Biodegradable Ceramics Calcium Phosphates

• Almost all bioresorbable ceramics are variations
  of calcium phosphate
• Uses
• repair material for bone damaged trauma or
  disease
• void filling after resection of bone tumours
• repair and fusion of vertebrae
• repair of herniated disks
• repair of maxillofacial and dental defects
• ocular implants
• drug-delivery

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Biodegradable Ceramics Calcium Phosphate

• Structure resembles bone mineral thus used for
  bone replacement
• Coating of metal implants to promote bone
  ingrowth
• Different forms exist depending on Ca/P ratio,
  presence of water, impurities and temperature

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Bioactive Ceramics Glass Ceramics

• Bioactive capable of direct chemical bonding
  with the host biological tissue
• Glass
• an inorganic melt cooled to solid form without
  crystallization
• an amorphous solid
• possesses short range atomic order ? BRITTLE!
• Glass-ceramic is a polycrystalline solid prepared
  by controlled crystallization of glass ? LESS
  BRITTLE

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Bioactive Ceramics Glass ceramics
A Bonding within 30 days B Nonbonding,
reactivity too low C Nonbonding, reactivity too
high D Bonding
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Classification based on tissue attachment
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Mechanical Properties