6. Intro to ceramics Flashcards
LOs
Main applications of ceramics
•Inlays
•Onlays
•Veneers
•Crowns
•Implant components
•Fixed partial prostheses
•Denture Teeth
Why’re ceramics so popular
- Used widely because of their optical similarities to teeth
- can mimic shade, translucency and lustre of tooth structure better than other materials
Disadvantages of ceramics
•Brittle in nature (can undergo very little deformation before they fail)
microstructure and defects/flaws play a major role in determining strength
1
Ceramics definition
2
Eg of ceramic materials
Type of bonding involved in ceramics
- ionic
- covalent
Are porcelain and ceramics the same
Porcelain is a ceramic but not all ceramics are porcelains
Main types of ceramics used in dent?
Key properties of dental ceramics?
Recap differences between glassy and crystalline states
1
What does it mean by the fact that ceramics are brittle?
2
What factors are do ceramics mechanical strength depend on?
1
What is fracture toughness
2
What is ceramics relative fracture toughness
3
Why is the theoretical tensile strength so high for ceramic compared to the actual tensile strength?
4
Tensile strength varies depending on?
Feldspathic Ceramics (Porcelain)
1
Overall structure
2
Main component in it?
1
- type of ceramic
-mainly glassy
–minor crystalline component
2
Feldspar is main component, KAlSi3O8
Feldspathic Ceramics (Porcelain)
1
When melted it forms
2
What happens when it cools
Feldspathic Ceramics (Porcelain)
1
Relative flexural strength?
2
Why is it used in aesthetics?
3
Is it mechanically strong?
1
typically 60-80MPa
- relatively weak
2
- Translucent in nature
- Can closely match the shade, translucency and luster of natural dentition
3
- But is low strength and prone to mechanical failures
- Addition of other crystal phases (e.g. fluorapatite) in contemporary materials increases mechanical performance
1
How may mechanical toughening of glassy cements be done
2
What condition must be met for this to be effective
3
EG
- subtle changes to crystalline component of ceramics is used to produce materials with different properties