Veneer - 2

Question 1

What does veneer prep depend on?

Answer 1

Method of fabrication
Occlusion
Desired aestehtic
Parafunction
Presence enamel at all proposed margins
Material: resin composite/ ceramic

Question 2

Indications for direct resin composite veneer?

Answer 2

Extensive damage incisal or buccal surface
Defective restoration
Discolouration not amenable to bleaching
Mal-aligned teeth
Congenitally deformed teeth
Pt doesn’t have time/finance for porcelain
Indirect porcelain would require excessive tooth structure removal

Question 3

Contraindications for direct resin composite veneer?

Answer 3

Inability to obtain correct shade
Inability to obtain correct contour
Inability to obtain correct surface characteristics
Inability to obtain proper isolation
Multiple teeth - extensive time and difficult achieve consistency

Question 4

Advantages of direct resin composite?

Answer 4

Very little or no tooth prep
Composite wear similar natural teeth - no iatrogenic damage adjacent teeth
Chairside repair

Question 5

Disadvantages of direct resin composite?

Answer 5

Colour stability - take up stain
Not as long lasting as porcelain
Not as strong as ceramic
More wear compared to ceramic

Question 6

What is longevity of direct RC veneer?

Answer 6

100% functional survival rate

Overall 84.6% at 5 years

Question 7

What is a direct RC veneer?

Answer 7

Veneer made chairside
One appointment needed
No or minimal prep

Question 8

What is an indirect RC veneer?

Answer 8

Need minimal preparation - 0.25-0.5mm reduction

Resin cement for cementation

Question 9

Adv indirect> direct

Answer 9

Reduced polymerisation shrinkage
Reduced marginal leak, sensitivity, recurrent caries, stain
Less technique sensitive
Physical properties composite improve with additional curing

Question 10

4 components of ceramic veneer?

Answer 10

Ceramic veneer
Acid-etched enamel surface
Silane coupling agent
Resin cement

Question 11

Advantage ceramic veneer?

Answer 11

Excellent aesthetic 
Excellent long term durability
Strength 
Marginal integrity 
Soft tissue compatibility
Minimal tooth reduction

Question 12

Disadvantage ceramic veneer?

Answer 12

Time consuming - multiple appts
Fragility 
Repairability difficult
Irreversible
Inability to trial cement restoration

Question 13

What are the 5 lab based techniques for making veneer?

Answer 13

1. Foil based
2. Castable ceramic
3. Refractory
4. CAD-CAM
5. Pressable

Question 14

How is foil based veneer made?

Answer 14

Porcelain layered on foil
Before try-in foil removed and porcelain etched
Foil permit repeatable removal of veneer from die
Thickness of foil creates space for cement

Question 15

How is castable ceramic veneer made?

Answer 15

Lost wax technique
Eliminate need for multiple firing
Require extrinsic staining

Question 16

How are refractory veneers made?

Answer 16

Most commonly used
Veneer fired onto die
Makes repeated fires impossible once veneer removed die
Tighter contacts
Absence of gaps
No room for tints

Question 17

What is a pressable veneer?

Answer 17

High pressure into mould
Excellent fit
Thin veneers

Question 18

Why should you prep teeth for veneers?

Answer 18

Stress concentration is less on veneers fitted to prepped teeth
Preparation remove prismatic and hyper mineralised enamel -resistant to etch
Prep completely in enamel to maximise resin bond

Question 19

What should the ideal tooth prep be?

Answer 19

Minimal
0.3-0.5mm mini chamber
0.6-0.8mm for incisal and buccal reduction ;
Buccal reduction 2 planes

Question 20

How can you increase strength of veneer-tooth?

Answer 20

Extend preparation over incisal edge

Question 21

When is a window prep useful?

Answer 21

Class II div II and class III incisors

• Contained on labial surface
• Minimal prep

Question 22

Why are tempories used?

Answer 22

Aesthetic
Reduce sensitivity
Diagnostic: contour, shape, length
Not always necessary - if dentine exposed mandatory

Question 23

What different tempories are available?

Answer 23

Direct composite - spot etch
Indirect made in lab
Matrix w/ protemp

Question 24

Why is cementation vital?

Answer 24

Allows veneer to become integral part of tooth structure

Share part of applied load during mastication

Question 25

How can you try-in veneer?

Answer 25

Should be tried prior cementation to assess fit and aesthetic
Try in paste
Careful as veneer fragile - use veneer carrier

Question 26

How to prepare veneer for cementation?

Answer 26

Veneer tx with HF acid
Clean fitting surface w/ acetone (40ml) to remove try in paste
Tx surface w/ phosphoric acid found improve bond
Rinse and dry

Question 27

What is silane coupling agent?

Answer 27

Apply to internet etched surface
Chemically bond to ceramic
Make ceramic surface hydrophobic

Question 28

What colour is standard cement?

Answer 28

Translucent

More opaque available if dark/discoloured

Question 29

How to cement a veneer?

Answer 29

Veneer carries - avoids handling and too much pressure (cause crack)
Veneer must be held in 2 planes during initial palatal polymerisation - if not gaps at margin
Resin space can be caused by insufficient luting resin

Question 30

What failures can occur with veneers?

Answer 30

Resin spaces
Fracture
Debonding

Question 31

Why can resin spaces occur?

Answer 31

Insufficient luting agent
Incorrect sequence of seating multiple veneers

Cause micro leakage, marginal stain, debond

Question 32

Why can fractures occur?

Answer 32

Static or cohesive or adhesive
Static
- Segment veneer fracture but remain on tooth
-Due excessive loading or polymerisation shrink

Cohesive

• Within body of porcelain due tensile load from excessive functional or parafunctional loading
• Result loss fragment

Adhesive

• Failure bonding interface
• Due weak bond or severe occlusal loading

Question 33

Why can debonding occur?

Answer 33

Must determine which bonded interfaced has failed
- If luting agent still on tooth - inadequate etching on veneer or no silane

-Luting on veneer - problem w/ bonding material, placement technique (more likely when predominately to dentine)