Restorative Materials - 01

• Metals
• Ceramics
• Polymers
• Composites

• Pure metals
• Intermetallic
• Compounds Alloys

• Crystalline ceramics
• Glasses
• Inorganic Salts

• Rigid polymers
• Waxes
• Elastomers

Mixture of two or more materials

• Composition: Chemical Identity, & Molecular Structure (crystalline, amorphous)
• Microstructure: Phases (grains, glass, grain boundaries, flaws)

• 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

• •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)

• Short range order of atoms
• long range disorder
• e.g., glass (ceramic), plastics (some plastics are crystalline)

the local atomic arrangement is repeated at regular intervals in the three dimensions of space. Crystals have long-range order.

the smallest atomic unit in crystal which are repeated in three directions.

Ionic (eg salt), Covalent (eg diamond, graphite), or Metallic

Quartz vs. Glass

• 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)

• the ________ properties of a material:
• physical
• Strength
• Ductility
• Hardness
• Elasticity
• Viscoelasticity
• Optical Properties
• Thermal Expansion
• Thermal Conductivity

• Pure metals
• Intermetallic
• Compounds Alloys

• 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

Metal oxides

• Grains (crystals)
• Grain boundaries
• Glass
• Flaws (porosity, dislocations)

Hydrocarbon resins (natural or synthetic)

• Long chain polymers (linear)
• Branched polymers
• Cross-linked polymers (strongest, denture teeth)
• Amorphous or amorphous & crystalline

• Different polymers connect together
• eg: Denture base, high impact strength, doesn't break when falls on ground.

• Mechanical Properties
• Optical Properties
• Thermal Properties
• Electrical Properties
• Magnetic Properties

• Potential to lose material due to dissolving in saliva.
• (e.g., materials with significant solubility include glass
• ionomers, zinc phosphate and carboxylate cements)

• (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

Diffusion of one substance into another. (e.g., coffee stain or saliva penetrating into a composite restoration)