Crown Dimensions

Question 1

How much occlusal reduction for a full gold crown?

Answer 1

1mm

Question 2

How much taper for crowns?

Answer 2

6°

Question 3

How is the total occlusal convergence achieved?

Answer 3

Holding a tapered bur parallel as this gives 3° taper on each side

Question 4

What margin should there be on a gold crown prep and how big should it be?

Answer 4

0.5mm (max) Chamfer

Question 5

Which burs should be used for a gold crown prep?

Answer 5

Long tapered coarse diamond (3°), Needle bur, Rugby shaped finishing bur

Question 6

How much extra clearance should be achieved by the functional cusp bevel?

Answer 6

0.5mm

Question 7

What angle should the functional cusp bevel be prepared?

Answer 7

45° to long axis of the tooth

Question 8

Function of the functional cusp bevel

Answer 8

Restores position of the cusp tip following occlusal reduction
Prevents perforation in areas of heavy contact
Prevents overcontoured restoration

Question 9

On which side should there be two planes of reduction?

Answer 9

Buccal

Question 10

Where are the functional cusps?

Answer 10

Upper palatal, lower buccal

Question 11

What is included in ‘finishing the prep’?

Answer 11

Smooth all surfaces
Round off sharp line angles
Smooth and well defined margin
Refine margin

Question 12

What are the 4 types of gold alloys used in dentistry?

Answer 12

I - soft
II - medium
III - hard
IV - extra hard

Question 13

Which type of gold alloy is used for crowns?

Answer 13

Type III

Question 14

Which metals are included in gold alloys?

Answer 14

Gold, silver, copper, platinum, zinc

Question 15

Which metal is added to gold for hardness?

Answer 15

Copper

Question 16

Benefits of gold cast restorations

Answer 16

Very strong in thin areas
Good for when there’s little interocclusal space
No wear on opposing teeth
Easily polished chair side

Question 17

Indications of gold alloys

Answer 17

Very strong in thin areas - good for areas with little interocclusal clearance
Bruxists

Question 18

Which type of gold alloy is used for inlays and onlays?

Answer 18

Types I to II

Question 19

What is an alternative alloy to gold alloys?

Answer 19

Silver alloys eg silver palladium, silver palladium copper

Question 20

Disadvantage of silver alloys over gold

Answer 20

Corrosion in mouth

Question 21

How much gold in type III gold alloys?

Answer 21

62-78% (75% most common)

Question 22

How much occlusal reduction for a posterior MCC and which bur to use?

Answer 22

1-1.5mm, tapered flat ended diamond

Question 23

Which margins and how many planes of reduction for a posterior MCC?

Answer 23

Bucally - radial shoulder 1.2mm, 2 planes of reduction
Palatal / lingual - chamfer 0.7mm, 1 plane of reduction

Question 24

What is the ideal taper for a posterior MCC prep?

Answer 24

6-10°

Question 25

What can be added to an anterior MCC prep for extra structural durability?

Answer 25

Incisal notch

Question 26

What type of ceramic is used for anterior MCC?

Answer 26

Porcelain

Question 27

How much occlusal reduction for all ceramic posterior preps?

Answer 27

2mm

Question 28

How much total reduction over the functional cusp bevel for an all ceramic prep?

Answer 28

2mm

Question 29

How much total reduction over functional cusp bevel for metal?

Answer 29

1.5mm

Question 30

What is a ceramic?

Answer 30

Inorganic non metallic solid produced by the application of heat then cooled

Question 31

Which material has the best aesthetics?

Answer 31

Ceramic

Question 32

What should be used for cutting matrices and other imps?

Answer 32

Lab knife with no 25 blade