Ceramic systems

Question 1

Ceramics

Answer 1

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

Question 2

Traditional ceramics

Answer 2

China
Porcelain
Bricks
Tiles 
Glasses

Question 3

Ceramic building block is

Answer 3

Silica (SiO2)

• crystalline e.g. quartz, cristoballite
• amorphous e.g. alumino-silicate glasses

Question 4

Crystalline silica

Answer 4

Tetrahedra

SiO2

Question 5

Silica glass

Answer 5

Orthosilicic acid

Si(OH)4

Question 6

Mixed oxide glass

Answer 6

Mixture of crystalline (SiO2 tetrahedra) or silica glass (orthosilicic acid SiOH4)

Question 7

Composition of early dental porcelain

Answer 7

Feldspar
Kaolin
Quartz

Question 8

Types of dental ceramics

Answer 8

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 9

Dental ceramic processing

Answer 9

Sintering
Casting
Hot pressing
CAD-CAM machining

Question 10

Feldspathic ceramic is weak

Answer 10

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 11

Metal ceramic restoration

Answer 11

Metal substructure – PFM Lost Wax Casting (Metal substructure)
Ceramic Sintering (Ceramic veneer)

Question 12

Metal ceramic production - problems

Answer 12

Space
0.5mm for metal substructure
1.0mm for ceramic veneer
Aesthetics
-metal substructure prevents light transmittance
-often appear opaque
-metal margin can be seen

Question 13

Technical metal ceramic production problems

Answer 13

Metal Ceramic Bond
Metal Ceramic Junction
Metal Ceramic Compatibility
-thermal expansion coefficient (shrinkage)
Support for Ceramic!!!! - remember

Question 14

Metal-ceramic compatibility

Answer 14

TEC of ceramic must be equal to or slightly less than that of the metal.
Metal = 13-14 ppm/°C
Ceramic = 8 ppm/°C
Therefore add Leucite (23ppm/°C)

Question 15

CAD demonstration

Answer 15

CAD can resolve some of the labour intensive design problems

Question 16

Indications for PFM

Answer 16

Single unit restorations
Multiple unit bridges
Support for partial dentures

Question 17

Variants of PFM

Answer 17

Metal Type: Bonding alloys
High Au content alloys.
Au-Pd alloys
Pd-Ag alloys
NiCr
CoCr

Question 18

High strength ceramic substructure restorations

Answer 18

The first was the Porcelain Jacket Crown (PJC)
-alumina reinforced ceramic core
-Vita (Vitadur N)
Glass Infiltrated Materials
-Lanthanum
Vita In-Ceram
-spinell
-alumina
-zirconia (actually an alumina/ zirconia mix)
Alumina substructures
-e.g. Procera All-Ceram (Nobel Biocare)
Zirconia e.g. 3M Lava

Question 19

PJC: alumina reinforced core

Answer 19

Good aesthetics but opaque core
Strength 80 MPa  (anteriors only)
Tooth reduction
Non-adhesive
Pt foil technique therefore poor marginal fit
GONE

Question 20

Flexural strength of PJC, In-Ceram Sp, In-Ceram Al, In-Ceram Zr, Procera

Answer 20

PJC 80-100 MPa
In-Ceram Sp 280-300 MPa
In-Ceram Al 350-380 MPa
In-Ceram Zr 530-550 MPa
Procera 690-700 MPa
Zircona 500-1200 MPa

Question 21

Translucency of glass infiltrated materials

Answer 21

**
Orginally produced via ‘slip casting’
GONE

Question 22

Alumina substructures

Answer 22

All rely on CAD CAM production
Procera: Centralised production from in-house design
GONE

Question 23

Zirconia e.g. 3M Lava

Answer 23

Many available on the market
In-house milling is readily available
Stained prior to sintering
Various translucencies
Requires sintering after firing (10 hours)
Extended sintering times for veneering ceramics
Can be used as monolithic material

Question 24

Resin bonded restorations

Answer 24

Veneers
Dentine bonded crowns
Inlays 
Onlays 
Partial Crowns

Question 25

Zirconia problems

Answer 25

Initial sintering time Bond between veneering ceramic and zirconia Large units have long sintering times Adjusting/ removing/ endodontic treatment

Question 26

Resin bonded restorations produced from

Answer 26

``` Feldspathic glass (shot-blast and bond) (Vita VM7) Leucite forming ceramic (HF etch and bond) (Empress) Lithium disilicate (HF etch and Bond) (Emax) -this material can be considered a substructure material in some applications ```

Question 27

Limitations of dentine resin bonded restorations?

Answer 27

Single units only | Weak, therefore anterior region only

Question 28

Lab problems of dentine resin bonded restorations??

Answer 28

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

Question 29

Lithium disilicate

Answer 29

Emax: Lithium disilicate Stronger Hot pressed (lost wax process) (Emax Press) Milled from a block using CADCAM (Emax CAD) This can be used as the definitive material or veneered with a sintered ceramic

Question 30

Lithium disilicate steps

Answer 30

``` CAD CAM production Set margin Cement lute Design restoration Send to production ```

Question 31

Ceramic systems

Answer 31

Metal-Ceramic High Strength Ceramic Substructure Resin Bonded + (Lithium disilicate)

Question 32

IRS-T Dental technology

Answer 32

``` Communication (Shade Assessment & Diagnostic Wax-up) Resin Bonded Restoration (Veneer) Full Gold Crown Metal Ceramic Restoration High Strength Ceramic Restoration ```