Ceramic systems for indirect restorations

Question 1

What is a ceramic?

Answer 1

Compounds of metallic and non-metallic elements: most frequently oxides, nitrides and carbides

Question 2

Examples of traditional ceramics?

Answer 2

China
Porcelain
Bricks
Tiles
Glasses

Question 3

What is the ceramic building block?

Answer 3

Silica (SiO2) - can form a:

• Crystalline structure e.g. quartz
• Amorphous structure e.g. alumino-silicate glasses

Question 4

Types of dental ceramics?

Answer 4

Feldspathic glasses
Leucite reinforced feldspathic glasses
Alumina reinforced feldspathic glasses
Lanthanum glass infiltrated alumina
Pure alumina
Zirconia
Glass ceramics
- Mica
- Lithium disilicate
- Canasite
- Apatite/Mullite

Question 5

Feldspathic ceramic is weak - how is it supported?

Answer 5

Support using one of 3 methods:

• Metal substructure – PFM
• High strength ceramic substructure
• Bond to the tooth and therefore use tooth as substructure. Resin Bonded Crown (DBC)

Question 6

Metal ceramic restorations are produced by?

Answer 6

Metal substructure made by PFM lost wax casting (metal substructure)
Ceramic sintering (ceramic veneer)

Question 7

Problems of metal ceramic production?

Answer 7

Space to fit materials as want:
- 0.5mm for metal substructure
- 1mm for ceramic veneer to hide metal substructure
Aesthetics
Metal substructure prevents light transmittance
Often appear opaque
Metal margin visible

Question 8

Technical problems of metal ceramic production? (do not learn)

Answer 8

Metal ceramic bond
Metal ceramic junction
Metal ceramic compatibility
Support for ceramic

Question 9

What can CAD do?

Answer 9

Resolve some of the labour intensive design problems

Question 10

Indications for PFM?

Answer 10

Single unit restorations
Multiple unit bridges
Support for partial dentures

Question 11

Variants of PFM?

Answer 11

Metal type: bonding alloys
High AU content alloys
Pd-Ag alloys
NiCr
CoCr

Question 12

What must the TEC of the metal and ceramic be?

Answer 12

TEC of ceramic and metal must match

Question 13

Type of high strength ceramic substructure restorations?

Answer 13

1st = porcelain jacket crown (PJC)
- Alumina reinforced ceramic core
- Vita
Glass infiltrated materials - 1st produced by slip casting then by CAD CAM
- Lanthanum
Vita In-Ceram:
- Spinell
- Alumina
- Zirconia

Question 14

Features of PJC: Alumina reinforced core?

Answer 14

Good aesthetics but opaque core
Strength 80MPa (anteriors only)
Tooth reduction
Non-adhesive
Pt foil technique = poor marginal fit
BUT cannot be made anymore

Question 15

Strength of PJC, in-ceram Sp, in-ceram Al, in-ceram Zr, Aluminia and zirconia?
(IMPORTANT)

Answer 15

Flexural Strength MPa

PJC = 80-100
In-Ceram Sp = 280-300
In-Ceram Al = 350-380
In-Ceram Zr = 530-550 
Aluminia (procera) = 690-700
Zirconia = 500-1200

Question 16

High strength ceramic substructures: Zirconia e.g. 3M Lava features?

Answer 16

Many on the market
Differ in strength and translucency 
Various translucencies (50%)
Lower strength
inITIAL SINTERING TIME
Bond between veneering ceramic and zirconia
Large units have long sintering times
Adjusting/removing/endo tx

Question 17

High strength ceramic substructures: alumina features?

Answer 17

Alumina substructures e.g. procera all-ceram
= relies on CAD CAM production
Procera: centralised production from in-house design
BUT not used today (still in pts mouths though)

Question 18

Types of resin bonded restorations?

Answer 18

Veneers
Dentine bonded crowns
Inlays
Onlays
Partial crowns

Question 19

Indications for zirconia?

Answer 19

Strength - multiple units, tooth reduction: monolithic

Aesthetic: substructure…

Question 20

What are resin bonded restorations made from?

Answer 20

Feldspathic glass
Leucite forming ceramic
Lithium disilicate

Question 21

Lab problems with resin bonded restorations?

Answer 21

Refractory model production
Duplication of die may compound errors
Lack of supporting structure results in fragile restoration, particularly the margins

Question 22

Limitations of resin bonded restorations?

Answer 22

Single units only

Weak = anteriors only

Question 23

Lithium disilicate features?

Answer 23

400Mpa
Pressed or milled
Substructure for veneer
Monolithic
Resin bonded = gains strength

Question 24

Types of ceramic systems?

Answer 24

Metal-ceramic
High strength ceramic substructure
Resin bonded plus lithium disilicate

Question 25

Upcoming materials?

Answer 25

Vita suprinity;
- Zirconia reinformed lithium disilicate (480MPa)
Dentsply: Celtra - pressing version
Vita Enamic (160MPa)