Ceramic restorative materials

Question 1

What are the four main groups of materials used in dentistry?

Answer 1

Ceramics, composites, metals, polymers

Question 2

What is a ceramic?

Answer 2

Inorganic, non metallic material comprising of compounds formed between metallic and non metallic elements by wintering at high temps

Question 3

What are the different microstructures of ceramics?

Answer 3

Glassy, crystalline or a mixture of both

Question 4

What is a drawback of porcelain?

Answer 4

Weak - easily cracks therefore contraindicated for posterior teeth

Question 5

What is feldspathic porcelain?

Answer 5

Porcelain with improved strength but still only used anteriorly

Question 6

What are the different types of dental ceramics?

Answer 6

Feldspathic, Leucites, Lithium disilicates, Alumina, Zirconia

Question 7

Examples of lithium disilicate ceramics?

Answer 7

EMAX, empress

Question 8

How can ceramics be classified?

Answer 8

Lots of different ways eg indications, composition, processing methods, firing temp, microstructure etc

Question 9

What are the different processing techniques for ceramics?

Answer 9

Condensation, hot isostatic pressing, computer aided milling

Question 10

How are ceramics processed using the condensation technique?

Answer 10

Foil adapted over the die
Ceramic layered over the die
It is vibrated to allow excess water to rise to the surface which can be blotted away
Restoration is fired

Question 11

Function of wrapping the die in foil before ceramic layering?

Answer 11

Allows space for cement

Question 12

What is hot isostatic pressing?

Answer 12

Similar to lost wax technique
Heat pressing a pre fabricated ingot

Question 13

Which processing technique do EMAX crowns use?

Answer 13

Hot isostatic pressing

Question 14

Advantage of CAD/CAM milling?

Answer 14

Can allow for a single visit
Quicker
Reduces human error

Question 15

Disadvantage of computer aided milling?

Answer 15

Machine is high cost

Question 16

Which type of tools are required for computer aided milling for ceramics?

Answer 16

Diamond encrusted

Question 17

Which type of tools are required for computer aided milling of zirconia?

Answer 17

Carbide

Question 18

What is the three stage process of computer aided milling?

Answer 18

Roughing, finishing, detailed sequence

Question 19

Benefit of pressed ceramics?

Answer 19

Superior margin fit which is especially useful where margin detail is not ideal

Question 20

What are the two types of microstructure for feldspathic ceramics?

Answer 20

Conventional (porcelain), Leucite reinforced (porcelain)

Question 21

What are some optical properties of feldspathic porcelain?

Answer 21

High translucency and colour stability
The ceramic thickness can impact light transmission

Question 22

What are the physical properties of feldspathic porcelain?

Answer 22

Microcracks form during function
Leucite reinforced is stronger
Not suitable for posterior restorations or areas of high masticatory load
Glazed feldspathic porcelain can damage the opposing dentition 40x more than a gold restoration

Question 23

Disadvantage of glazed feldspathic porcelain?

Answer 23

Wears away opposing dentition at a quick rate

Question 24

How to cement feldspathic porcelain?

Answer 24

Acid etch
Use of a silane coupling agent
Dual, light or self cure or self adhesive resin

Question 25

What are the two main processing techniques for lithium disilicate?

Answer 25

Ingot two stage crystallisation via pressing CAD three stage crystallisation process

Question 26

What are the optical properties of lithium disilicate?

Answer 26

Very good, maybe better than porcelain

Question 27

What are the two techniques for staining lithium disilicates?

Answer 27

Cut back technique Layering technique

Question 28

What type of ceramics are EMAX and Empress?

Answer 28

Lithium disilicate

Question 29

Indications of lithium disilicate restorations?

Answer 29

Anterior or posterior

Question 30

Contraindications of lithium disilicate ceramics?

Answer 30

Not for deep subgingival preps in patients with bruxism or greatly reduced dentition

Question 31

What are the preparation design requirements for lithium disilicate crowns?

Answer 31

No angles or sharp edges Prepare margins with deep chamfer or rounded shoulder Smooth finish line Even reduction of the anatomical shape Ensure the indicated dimensions match the stipulated minimum wall thickness that manufacturer recommends

Question 32

How do you cement lithium disilicate restorations?

Answer 32

Conventionally or adhesively RMGIC if prep is retentive and moisture control is difficult Adhesive cementation is best - etch, apply silane, apply adhesive, apply resin cement

Question 33

What type of material is Nobel Procera AllCeram?

Answer 33

Alumina

Question 34

Applications of alumina in crown and bridge work?

Answer 34

Nil

Question 35

Applications of alumina?

Answer 35

Implant abutments for Nobel pearl implants Orthodontic brackets Filler for composite and bone cement materials

Question 36

Indications for alumina restorations?

Answer 36

PJC - anterior teeth but insufficient strength for posterior In-ceram alumina - Implants for single teeth, anterior three unit fixed partial denture, inlays, anterior crowns

Question 37

What are the preparation design requirements for alumina restorations?

Answer 37

Axial reduction of 0.8 - 1.0mm Occlusal reduction of 2mm Don't use sharp line angles, boxes with butt shoulders etc Keep margins supragingivally wherever possible, or equigingival

Question 38

What do we use to cement alumina restorations?

Answer 38

GIC or RMGIC Can do air abrasion on the fitting surface to increase surface area and follow up with a phosphate based coupling agent

Question 39

What is the purpose of doing air abrasion on the fitting surface of alumina crowns?

Answer 39

Increases the surface area to aid adhesion

Question 40

Which type of coupling agent should be used with alumina restorations?

Answer 40

Phosphate based

Question 41

What are the three allotropic forms of zirconia?

Answer 41

Monoclinic, tetragonal, cubic exceeding

Question 42

Which allotropes of zirconia need to be stabilised?

Answer 42

Tetragonal and cubic phases

Question 43

Benefit of zirconia?

Answer 43

Strength

Question 44

What are the preparation requirements for a zirconia restoration?

Answer 44

Monolithic - Axial reduction of 0.8mm Veneering porcelain - axial reduction of 1.5mm, occlusal reduction of 1.2-1.5mm

Question 45

What are the optical properties of zirconia?

Answer 45

White opacity - good for masking things Staining can be added for aesthetics

Question 46

What are the physical properties of zirconia?

Answer 46

Tougher and stronger than conventional glass ceramics Hardness - can pose concerns for wear of opposing teeth especially for bruxists

Question 47

What is the risk of zirconia for bruxists?

Answer 47

Wear of opposing teeth

Question 48

What is the toughest and strongest ceramic?

Answer 48

Zirconia

Question 49

Indications for zirconia?

Answer 49

Fixed dental prosthesis excluding veneers Three used fixed dental prosthesis Material of choice for resin bonded bridges

Question 50

How is zirconia cemented?

Answer 50

Cannot be etched Fitting surface prepared by sandblasting Apply MDP containing ceramic primer Use a self adhesive resin cement which doesn't require separate etching or bonding