1 - Treatment planning for fixed prosthodontics

Question 1

Define fixed prosthodontics.

Answer 1

• attached or fixed dental prostheses
• also known as indirect restorations

Question 2

List types of indirect restoration.

Answer 2

• veneers
• inlays and onlays
• crowns
• post and cores
• bridgework

Question 3

What should be examined in the lips for an E/O exam?

Answer 3

• vermillion borders
• commissures
• smile line

Question 4

When is a face bow required in fixed prosthodontics?

Answer 4

• when changing occlusion or restoring key teeth in guidance
• used to mount cast in correct maxillary relationship to TMJ

Question 5

What is a diagnostic wax up?

Answer 5

• provisional wax up of restoration
• check aesthetics and occlusion
• allows patient to see provisional result

Question 6

What stage of treatment planning does fixed prosthodontics fall under?

Answer 6

Reconstructive

Question 7

When are veneers indicated?

Answer 7

• improve aesthetics
• change teeth shape/contour
• correct peg laterals
• reduce or close proximal spaces or diastemas
• align labial surfaces of instanding teeth
• enamel defects

Question 8

What is the Gurel minimal preparation technique for veneers?

Answer 8

• wax up
• stent
• intra-oral mock up
• preparation into mock up

Question 9

When are veneers contraindicated? (10)

Answer 9

• poor OH
• high caries rate
• interproximal caries or unsound restorations
• gingival recession or root exposure
• high smile line
• if extensive prep is required (>50% no loner enamel)
• labial positioned, severely rotated or overlapping teeth
• extensive TSL
• heavy occlusal contacts
• severe discolouration

Question 10

When are inlays/onlays indicated?

Answer 10

• TSL to increase OVD
• fractured cusps
• restoration of root treated teeth
• replace failed direct restorations

Question 11

When are inlays/onlays contraindicated?

Answer 11

• active caries
• periodontal disease
• time
• cost

Question 12

When are crowns indicated?

Answer 12

• protect weakened tooth structure
• improve or restore aesthetics
• retainer for bridgework
• when RPD design indicates
• restore tooth function

Question 13

When are crowns contraindicated?

Answer 13

• active caries
• periodontal disease
• more conservative options available
• lack of tooth tissue for prep
• unable to provide post and core
• unfavourable occlusion

Question 14

What are the principles of crown preparation?

Answer 14

• preservation of tooth structure
• retention and resistance
• structural durability
• marginal integrity
• preservation of periodontium
• aesthetic considerations

Question 15

Describe preservation of tooth structure.

Answer 15

• avoid weakening tooth structure and damage to the pulp
• balance criteria for retention and resistance with structural durability

Question 16

What does under preparation of crowns result in?

Answer 16

• poor aesthetics
• periodontal and occlusal interference
• insufficient thickness of restoration

Question 17

What does over preparation of crowns result in?

Answer 17

• damage to pulp
• tooth strength being compromised

Question 18

Define retention in crown preparation.

Answer 18

Prevents removal of restoration along the path of insertion or long axis of tooth preparation

Question 19

Define resistance in crown preparation.

Answer 19

Prevents dislodging of restoration by forces in apical or oblique direction, and movement of the restoration by occlusal forces

Question 20

How do you achieve retention and resistance in crown preparation?

Answer 20

• taper of opposing walls (6-10 degrees)
• length of walls
• path of insertion
• grooves or slots (rarer)

Question 21

How does the wall length hinder displacement of crowns?

Answer 21

Longer walls interfere with tipping forces, has to slide more before it dislodges

Question 22

How does the path of insertion hinder displacement of crowns?

Answer 22

Having fewer/only one path of insertion improves retention, as there is less directions the restoration can become dislodged

Question 23

How do you achieve structural stability in crown preparation?

Answer 23

• bulk of material must be adequate to withstand occlusal forces
• achieved by occlusal reduction, functional cusp bevel and axial reduction

Question 24

What should the occlusal reduction be on posterior crown preparations?

Answer 24

At least 2mm

Question 25

How do you achieve marginal integrity in crown preparation?

Answer 25

Achieved using different types of burs

Question 26

What are the different marginal finish configurations in crown preparation?

Answer 26

• knife edge
• bevel
• chamfer *
• shoulder *
• bevelled shoulder

Question 27

How do you achieve a chamfer finish line?

Answer 27

Rounded tapered bur

Question 28

How do you achieve a shoulder finish line?

Answer 28

Fissure bur

Question 29

What type of crown requires a chamfer finish line?

Answer 29

Metal based

Question 30

What types of crown require a shoulder finish line?

Answer 30

Ceramic

Question 31

How do you achieve preservation of the periodontium in crown preparation?

Answer 31

• margins are smooth and fully exposed to cleaning
• margin is supra gingival or at the gingval margin

Question 32

How do you achieve aesthetics in crown preparation?

Answer 32

• be aware of high smile lines
• material choice
• aesthetic v function (ie bruxists)

Question 33

When is bridgework indicated?

Answer 33

• missing teeth
• aesthetics
• improve occlusal stability
• improve function
• periodontal splinting
• restoring OVD
• patient preference

Question 34

When is bridgework contraindicated?

Answer 34

• damage to tooth and pulp
• secondary caries
• effect on periodontium
• cost
• failures