LO 3 Flashcards
What are the three basic forms of physical structures?
Solid, liquid, gas
What are the favourable aspects of solids in dental materials?
Shape/volume (build it up), strength and stability
What do you need to understand about liquids?
- Volume but no definite shape
- Viscosity for different uses
Define thixotropic
A characteristic of some gels and liquids that they will flow more readily under mechanical force (mixing, stirring, or shaking)
What do you need to know about gasses?
No volume or shape, e.g nitrous oxide, oxygen, etc.
Name 2 examples of dental materials that exist in multiple states
- Plaster or stone- mixed in a liquid and hardens
- Fluoride foam - liquid and a gas
What are the physical properties of dental materials?
Melting/boiling points, density, viscosity, thermal conductivity, thermal expansion
Define density
A measure of the weight of a material compared to its volume (brick vs. sponge)
What are the mechanical properties of dental materials?
Hardness, stress, resilience, toughness, fatigue, durability
What are the chemical considerations of dental materials
Chemical reactions that change one material into something else (corrosion, galvanism)
How are dental materials classified?
Preventative, therapeutic, restorative
Describe preventative materials with an example
Used to prevent diseases - fluoride pit and fissure sealants
Describe therapeutic materials including an example
Used to treat disease (medical bases, topical treatments for periodontal disease
How long are temporary restorative materials meant to last?
Days to weeks
How long should permanent restorative materials last?
Years - very long lasting
How long should intermediate restorative materials last?
Several weeks to months
What 4 things do you need to consider when mixing compounds?
- Mixing time -time to blend to homogeneous
- Working time - time to work in mouth before initial set
- Initial set - material can no longer be manipulated
- Final set - material has reached ultimate state
Name the 3 chemical reaction types used to set restoration materials
- Chemical setting - reaction when catalyst and base are combined
- Light activated - blue light used to indicate setting process
- Dual set - slow chemical reaction (increased with blue light)
What will affect the outcome of a compound?
- Correct ratios
- Temperature
- Moisture
- Shelf life
What is a shelf life and what impacts it?
Time a material can be stored before becoming unusable
- Temperature
- Humidity
- Packaging
- Storage
- Experation dates
