6. Intro to ceramics Flashcards by Madeeha Umair

LOs

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Main applications of ceramics

•Inlays
•Onlays
•Veneers
•Crowns
•Implant components
•Fixed partial prostheses
•Denture Teeth

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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

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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

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1
Ceramics definition

2
Eg of ceramic materials

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Type of bonding involved in ceramics

ionic
covalent

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Are porcelain and ceramics the same

Porcelain is a ceramic but not all ceramics are porcelains

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Main types of ceramics used in dent?

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Key properties of dental ceramics?

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Recap differences between glassy and crystalline states

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1
What does it mean by the fact that ceramics are brittle?

2
What factors are do ceramics mechanical strength depend on?

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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?

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Feldspathic Ceramics (Porcelain)

1
Overall structure

2
Main component in it?

1
- type of ceramic
-mainly glassy
–minor crystalline component

Feldspar is main component, KAlSi3O8

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Feldspathic Ceramics (Porcelain)

1
When melted it forms

2
What happens when it cools

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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

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1
How may mechanical toughening of glassy cements be done

2
What condition must be met for this to be effective

3
EG

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subtle changes to crystalline component of ceramics is used to produce materials with different properties

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Eg of different ceramic microstructures

ceramic manufacturing methods

can classify diff ceramic materials not only by their structure but also by their manufacturing methods

1
What is sintering of dental ceramics?

2
What are the 2 main types of crystalline reinforced sintered dental ceramics?

SINTERED ALL-CERAMIC RESTORATION:
ALUMINA-BASED MATERIALS

1
Is it still used?

2
Alumina formula and % added?

1
Rarely used system now – but many functioning crowns out there

2
•Alumina is an aluminum oxide, Al2O3
•Typically added in levels of up to 40-50% by weight

SINTERED ALL-CERAMIC RESTORATION:
ALUMINA-BASED MATERIALS

Key problems with it?

shrinkage during sintering leading to dimensional inaccuracies
During sintering procedure shrinkage between 10-20% can occur
opacity of core necessitates veneering with glassy material to achieve esthetics

SINTERED ALL-CERAMIC RESTORATION:
ALUMINA-BASED MATERIALS

1
Good bond with glass phase?

2
How is it formed? Temp?

3
Flexural strength? What does this depend on?

SINTERED ALL-CERAMIC RESTORATION:
ALUMINA-BASED MATERIALS

1
Good bond with glass phase?

2
How is it formed? Temp?

3
Flexural strength? What does this depend on?

SINTERED ALL-CERAMIC RESTORATION: ALUMINA-BASED MATERIALS 1 Good bond with glass phase? 2 How is it formed? Temp? 3 Flexural strength? What does this depend on?

SINTERED ALL-CERAMIC RESTORATION: LEUCITE-REINFORCED MATERIALS 1 Compound made of? 2 Flexural strength? 3 4 What happens during cooling 5 Positives

HEAT-PRESSED ALL-CERAMIC RESTORATIONS 1 What is it? 2 What happens during the process? Pressure? Temp? 3 Why was it introduced?

HEAT-PRESSED ALL-CERAMIC RESTORATIONS? 1 Why is Heat pressing is typically used over classical sintering? 2 What is the final step for final-heat pressed ceramics? 3 Ceramic materials used in heat pressing?

HEAT-PRESSED ALL-CERAMIC RESTORATIONS: LEUCITE-REINFORCED MATERIALS 1 Properties? 2 Final porosity % vol? 3 Final flexural strength 4

HEAT PRESSED CERAMICS: LITHIUM DISILICATE MATERIALS 1 Properties 2 final porosity by % vol? 3 Flexural strength

SLIP-CAST ALL-CERAMIC RESTORATIONS 1 What is it 2 How is it formed 3 Types of materials used 4 Commonly used today?

CAD-CAM All-Ceramic Restorations 1 What does it stand for? 2 What happens 3 Disadvantages 4 Common method?

CAD-CAM All-Ceramic Restorations 1 Bulk ceramics are either (make q) 2 2 main types of machining? 3 What is hard machining 4 Advantages of hard machining 5 Limits of hard machining 6 What is soft maching

CAD-CAM All-Ceramic Restorations: Fully Sintered Materials 1 Three types of materials are currently used in the fully sintered state in CAD-CAM restorations?