Restorative Materials - 01

  1. Materials / Biomaterials Classification
    • Metals
    • Ceramics
    • Polymers
    • Composites
  2. Metals
    • Pure metals
    • Intermetallic
    • Compounds Alloys
  3. Ceramics
    • Crystalline ceramics
    • Glasses
    • Inorganic Salts
  4. Polymers
    • Rigid polymers
    • Waxes
    • Elastomers
  5. Composites
    Mixture of two or more materials
  6. Composition vs. Microstructure
    • Composition: Chemical Identity, & Molecular Structure (crystalline, amorphous)
    • Microstructure: Phases (grains, glass, grain boundaries, flaws)
  7. Composition
    • Its chemical identity or the chemical identity of its components (also called “phases”)
    • Ex. 1: the composition of gypsum is Ca(SO4).2H2O
    • Ex. 2: the composition of the components (or phases) of silver amalgam is Ag3Sn, Ag2Hg3, Sn7Hg, etc.
    • Determines the chemical properties of a material: Solubility, Sorption, Tarnish & Corrosion, Cytotoxicity & Allergenicity, Galvanism, Passivation, Chemical Bonding, Wetting
  8. Crystalline
    • •Short range order of atoms or ions
    • •Repeats long range in three dimensions
    • •External form represents internal atomic arrangement
    • •e.g., tri-calcium phosphate (apatite), calcium sulfate (gypsum), zirconium oxide (all ceramic)
  9. Amorphous
    • Short range order of atoms
    • long range disorder
    • e.g., glass (ceramic), plastics (some plastics are crystalline)
  10. Crystalline phase:
    the local atomic arrangement is repeated at regular intervals in the three dimensions of space. Crystals have long-range order.
  11. Unit cell:
    the smallest atomic unit in crystal which are repeated in three directions.
  12. Crystalline Structure can be
    Ionic (eg salt), Covalent (eg diamond, graphite), or Metallic
  13. SiO2 - Crystalline vs. Amorphous
    Quartz vs. Glass
  14. What is the “microstructure” of a material?
    • The arrangement and distribution of the phases within a material
    • “Phases” are distinctly identifiable crystals, pores, glass, fibers, etc. that can be observed within the material with the unaided eye or with magnification (i.e., light microscope or electron microscope)
  15. The microstructure (and composition) determines
    • the ________ properties of a material:
    • physical
    • Strength
    • Ductility
    • Hardness
    • Elasticity
    • Viscoelasticity
    • Optical Properties
    • Thermal Expansion
    • Thermal Conductivity
  16. Metals - composition
    • Pure metals
    • Intermetallic
    • Compounds Alloys
  17. Metals - Microstructure
    • Grains (crystals)
    • Grain boundaries
    • Flaws (porosity, dislocations)
    • assembly of grains (crystals), grain boundaries, pores, and glass in the microscopical image
    • each grain is a single crystal with a distinct spacial orientation; grains come together at the “grain boundaries" during solidification of the metal from the liquid state during cooling
    • The size of the grains of the material can affect the physical properties (such as ductility of metals and strength of ceramics)
    • Grain boundaries are usually areas of weakness of the material and are prone to corrosion
  18. Ceramics - Composition
    Metal oxides
  19. Ceramics - Microstructure
    • Grains (crystals)
    • Grain boundaries
    • Glass
    • Flaws (porosity, dislocations)
  20. Polymers - Composition
    Hydrocarbon resins (natural or synthetic)
  21. Polymers - Microstructure
    • Long chain polymers (linear)
    • Branched polymers
    • Cross-linked polymers (strongest, denture teeth)
    • Amorphous or amorphous & crystalline
  22. Copolymer
    • Different polymers connect together
    • eg: Denture base, high impact strength, doesn't break when falls on ground.
  23. Physical Properties
    • Mechanical Properties
    • Optical Properties
    • Thermal Properties
    • Electrical Properties
    • Magnetic Properties
  24. Solubility
    • Potential to lose material due to dissolving in saliva.
    • (e.g., materials with significant solubility include glass
    • ionomers, zinc phosphate and carboxylate cements)
  25. Adsorption
    • (Similar to “adhesion”) – one substance sticking to the surface of another substance through weak chemical bonding and wetting (hydrogen bonding or Van der Waals forces) (e.g., coffee stain on the surface of tooth enamel)
    • Surface only, no penetration
  26. Absorption
    Diffusion of one substance into another. (e.g., coffee stain or saliva penetrating into a composite restoration)
Card Set
Restorative Materials - 01
Restorative Materials - 01