Intro to Biomaterials-Amalgam & Class I and Class V Restorations Flashcards
What are the four major classes of dental materials?
- Metals and Alloys
- Porcelains and Ceramics
- Polymers
- Composites
Who regulates dental materials?
American Dental Association
Food and Drug Administration
How does the atomic structure affect the dental materials?
Atomic structure determines mechanical and physical properties of materials
What are the types of interatomic bonds?
Primary
- Ionic, covalent, metallic
Secondary
- H bonds, Van der Waals forces
What is an ionic bond?
Electrostatic attraction of positive and negative charges
- involves electron transfer between ions
What are the properties of an ionic bond?
- non-directional, strong bond
- no free electrons
- good thermal and electrical insulator
What are some examples of dental materials that use ionic bonds?
ceramics
gypsum
What is a covalent bond?
2 atoms share an electron
What are the properties of a covalent bond?
- directional bond
- low electrical and thermal conductivity
- water insoluable
What are some examples of covalent dental materials?
polymers
composite
What is a metallic bond?
Cluster of positive metal ions surrounded by a gas of electrons
What are the properties of a metallic bond?
- non-directional bonds
- high electrical and thermal conductivity
What are some examples of metallic dental materials?
amalgam and gold alloys
What are the four classifications of material properties?
biological
surface
physical
mechanical
What is the biological classification of material properties?
The biological response to a material when in contact with the human body (ex: gingivitis from plaque)
What is the surface classification of material properties?
The unique properties of a material associated with its surface (ex: denture retention, adhesive bonding)
What is the physical classification of material properties?
Depend on the type of atoms and the bonding present in material; size or shape have NO AFFECT (ex: optic and thermal)
What is the mechanical classification of material properties?
Reaction of a material to the application of an external force, size and shape of specimen AFFECT properties
What is fracture strength?
how much stress a material can withstand before it breaks
What type of stress is compressive?
pushing
- Measure of the stress necessary to fracture a material by 2 opposing forces directed toward each other
What type of stress is tensile?
pulling
- Measure of the stress necessary to fracture a material by 2 opposing forces directed away from each other
What type of stress is shear?
sliding
- Stress necessary to rupture a material by 2 opposing parallel forces directed toward each other but not in the same plane
What type of stress is torsion?
twisting
What type of stress is flexure?
bending
- Measure of stress to cause failure in bending
What is the highest strength measure for most materials?
compressive strength
What force pushes atoms and structures closer together?
compressive