Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

IRS > posterior crowns > Flashcards

posterior crowns Flashcards

1
Q

What are the reasons to restore a compromised tooth?

A
  • Restoring function (first) and aesthetics (second)
  • Restoring structural integrity and resisting fracture
  • Integrating with other prosthesis (incorporate the partial denture)
  • Preserving remaining tooth tissues and increasing fracture resistance
  • Improves patient confidence and psychology
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is special about endodontically treated teeth?

A

Weakened due to access cavity prep
Loss structural integrity associated with loss of roof of the pulp chamber
Loss of dentine elasticity (becomes brittle)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

When is cuspal protection required in a posterior tooth?

A

Loss of marginal ridges
Loss of substantial tooth structure
Heavily restored tooth

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is cuspal protection achieved?

A

Adhesive restorations - can be direct or indirect (composite, ceramic or metal)
Cusp-coverage cast restorations - prepare the tooth as well as cuspal reduction
Full coverage restorations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the different design considerations for posterior crowns ?

A 
Is the tooth in function?
Appearance
Adjacent teeth
Periodontal tissues
Pulp
Retention of the crown to the tooth
Materials
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What needs to be considered with the periodontal tissues when designing a posterior crown?

A

Margins are plaque retentive - if have perio disease more prone to plaque retention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the different ways of gaining retention for the crown on posterior teeth

A

Dentine bonded is bonded to the tooth - requires less prep.

All ceramic: requires bigger prep - prep includes retention

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What processes during the crown prep can lead to pulpal death?

A

Thermal damage
Local anaesthesia - adrenaline reduces blood supply to the tooth.
Desiccation - open tubules and keep drying the tooth by spraying air
Bacterial contamination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the probability of pulpal death following crown preps?

A

10-19%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

if do a 1.2mm shoulder prep, what is the resulting dentine width?

A

0.7mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the different threats when preparing the tooth?

A 
Bacterial toxins 
Desiccation
Thermal
Chemical
Osmotic
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the different options of material that can be used for the posterior crown?

A

Metal - minimal tooth reduction, strong in thin section, can be adjusted intra orally
Metal-ceramic - metal core layered with porcelain
Ceramic - dentine bonded and high strength core - strong core layered with translucent porcelain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is type I gold alloy?

A

Was hard enough to stand up to biting forces but soft enough to burnish against the margins of a cavity prep
Was used for one-surface inlays

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is type II gold alloy? (soft)

A

Was less burnishable but hard enough to stand up in small, multiple surface inlays that did not include buccal or lingual surfaces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is type III gold alloy? (medium)

A

This one is most commonly used for all-metal crowns and bridges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What does a typical type III gold alloy include? (hard)

A

Gold 75%, silver 10%, copper 10%, palladium 3%, zinc 2%

17
Q

What is type IV gold alloy? (extra hard)

A

Was used for partial denture frameworks but was not used for fixed prosthetic’s

18
Q

How long do you expect a full gold crown to last?

A

more than 10 years long-term

19
Q

What are the advantages of a full gold crown?

A

Minimal prep
High longevity
Adjust occlusion in mouth
nice marginal adaptation

20
Q

What are the disadvantages of a metal-ceramic crown?

A

There’s extensive buccal tooth reduction.

Only the metal component can be adjusted intra-orally

21
Q

What are the 3 PFM allow types?

A

High-nobel alloys
Nobel alloys
Base-metal alloys

With high-nobel being the more expensive

22
Q

What are high-noble alloys?

A

have a minimum of 60% noble and a minimum of 40% by weight of gold
Also contains a small amount of tin, indium or iron which provides an oxide layer to provide chemical bond to porcelain

23
Q

What are noble alloys? (gold, palladium or silver)

A

contains at least 25% by weight noble metal .They have high strength, durability, hardness and ductility

24
Q

What are base metal alloys?

A

Contains less than 25% noble metal
Harder, stronger, and have twice the elasticity.
Castings can be made thinner and still remain the rigidity needed to support the porcelain.
Were heavily used because of their low cost and high strength characteristics
Nickel and beryllium are the 2 most commonly used constituents - can cause allergic reactions when in contact with gingiva

25
Q

How long does PFM last?

A

5 year survival 93.3%

26
Q

What are the positives and negatives of all ceramic posterior crowns?

A 
High strength ceramic core
Most aesthetic
Low edge strength
Requires extensive reduction
Intra-oral adjustment not possible
27
Q

How long does all ceramic last?

A

5 year survival = 90%

28
Q

What are the shillinberg principles of tooth prep?

A 
Preservation of tooth structure
Retention - axial direction
Resistance
Structural durability
marginal integrity
29
Q

What does the retention form prevent?

A

Dislodgement of the crown in an axial direction

30
Q

What does resistance form prevent?

A

dislodgement of the crown due to rotation from a lateral load

31
Q

What is important when doing the tooth prep design?

A

A clear finish line at margins
Ceramic margins should be butt-joint rounded shoulder 90 degrees and follow the gingival margin
Metal margins = chamfer
All preparation line angles and point angles are best rounded

32
Q

What is the tooth prep for all ceramic?

A

Minimum occlusal reduction = 1.5mm >2mm in areas of stress
Shoulder margin
5 degree taper

33
Q

What is the tooth prep of PFM crown

A

Deep prep on the labial for metal and porcelain
Buccally lighter <1mm on the lingual side
functional cusp bevelled for more material thickness
Smooth shoulder with adequate depth

34
Q

What is the full gold crown prep?

A

1mm chamfer, parallel, sightly tapered

35
Q

What happens at phase 1 of the clinical stage?

A 
Pre-op clinical radiographic assessment 
further investigation
study models
diagnostic wax up
periapical radiograph
treatment planning 
informed consent
36
Q

What happens at phase 2 of the clinical stage?

A 
Tooth build up and preparations
impression
shade selection
occlusal record 
temporisation 
fabrication (lab)
37
Q

What happens at phase 3 of the clincal stage?

A 
Removal of temp crown
try-in of definitive crown
cementation of definitive crown
occlusal check
review

IRS (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions