Generic

Question 1

FVC Criteria

Answer 1

1mm occlusal reduction maintaining morphology

1. 5mm functional cusp bevel reduction
2. 5mm axial reduction with Supragingival chamfer margin

6 degree taper (check for undercuts)

Question 2

Posterior MCC criteria

Answer 2

If metal occlusal surface:
1 mm non-functional cusp 1.5 mm functional cusp

If metal + porcelain occlusal surface:
1 .5 mm non-functional cusp
2 mm functional cusp

1.2 - 1.5mm axial reduction with shoulder margin

Question 3

Anterior MCC criteria

Answer 3

2mm incisal reduction
1.2 – 1.5mm labial shoulder equidistant to gingival margin
Two-plane reduction labially
0.5mm supragingival palatal chamfer

Question 4

Ideal properties of an Elastomeric Impression material

Answer 4

• Non-toxic and non-irritant

• Acceptability to patient
Setting time
Taste
Consistency

• Accuracy
Surface reproducibility
Dimensional stability

•	Use of material 
Ease of mixing 
Working time 
Setting time 
Handling of material 

• Compatible with model materials

• Economics of material
Cheap
Long shelf life
Accuracy (saves redoing impression)

• Confidence that you can disinfect them

Question 5

Characteristics of Elastomeric Impression Materials

Answer 5

BASE – Packaged as a paste in a tube, as a cartridge, or as putty in a jar

CATALYST – also known as the accelerator, is packaged as a paste in a tube, as a cartridge or as a liquid in a bottle with a dropper top.

Question 6

Forms of Elastomeric Materials

Answer 6

Light-bodied

• Also referred to as syringe type or wash type
• Used because of its ability to flow in and about the details of the prepared tooth

Medium-bodied

• Referred to as tray type
• Much thicker
• Their stiffness helps to force the light-bodied material into close contact with the prepared teeth and surrounding tissues to ensure a more accurate impression of the details of a preparation

Putty
- Must be manually kneaded

NB: Viscosity governed by filler content

Question 7

Curing Stages of Elastomeric Materials

Answer 7

INITIAL SET

• First stage
• Results in stiffening o the paste without the appearance of elastic properties
• The material may be manipulated only during this first stage

FINAL SET

• Second stage
• Begins with the appearance of elasticity and proceeds through a gradual change to a solid rubberlike mass
• Material must be in place in the mouth before the elastic properties of the fial set begin to develop

FINAL CURE

• Last stage
• Occurs from 1-24 hours

Question 8

Types of Elastomeric Materials

Answer 8

Polysulfide
Polyether
C-silicone (Condition-Silicone)
A-silicone (Addition-silicone) / Polyvinyl siloxanes

Question 9

INLAY = Lab made indirect restoration that sits within a tooth

Inlay Indications

Answer 9

INDICATIONS
o Subgingival cavity
o Ant achieve adequate moisture control to place direct composite, but pt demanding aesthetic restoration indirect inlay
o Small – medium cavity (as amalgam)
e.g Small MO/DO cavities in molars/premolars
conservation MOD in molars
o Low caries rate

Good support for cusps from remaining tooth tissue
about 1/3rd buccal-lingual width
height: width < 1:1
canine guidance
- If group function may get cuspal/wall fracture as teeth subject to lateral forces

**But may have wedge-like action on tooth cuspal fracture

Question 10

Onlay Indications

Answer 10

INDICATIONS 
o	Conservation of tooth tissue
o	Provides CUSPAL COVERAGE 
o	Low caries risk 
o	Teeth with larger restorations, but sound B/L walls needing cuspal coverage 
Wider MODs
MODs in premolars 
o	Endodontically treated teeth 
-	Same purpose as crown but less destructive! – High aesthetic demand  contraindication; restoration margins visible 
o	Weakened cusps – enamel severely undermined 
o	Fracture
o	Over ½ buccal-lingual width 
o	Height: width > 1:1
o	Parafunction – bruxism  tooth wear, lost occlusal surface but not lost all clinical height 
o	Excessive cusp wear 
o	Group function