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3rd Yr- CSB- Extra-coronal restorations > Inlays and Onlays > Flashcards

Inlays and Onlays Flashcards

1
Q

How do we treat caries in a tooth?

A

We remove the caries using a handpick

Then we place a restoration to fill the cavity

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2
Q

What are some of the negative consequence of removing tooth tissue when treating caries

A

Weakening of the walls and cusps of the tooth which can lead to fractures and cracks

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3
Q

Give examples of factors that can increase the risk of a posterior teeth fracturing

A
  1. If the height to base ratio is more than 1 (ie the height is more than the base)
  2. Root treated teeth
  3. A group function occlusion
  4. Clenching or grinding
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4
Q

Are rooted treated teeth more or less likely to fracture in comparison to normally restored teeth

A

Root treated teeth

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5
Q

Which root filled tooth is more likely to fracture : crowned or uncrowned

A

Uncrowned is at a 6 times greater risk of fracturing

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6
Q

How can we manage weakened cusps?

A
  1. Bonding

2. Cuspal coverage

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7
Q

Is bonding useful for managing weekend cusps?

A

Yes it is seen to have improved the fracture resistance of teeth by bonding on natural premolars

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8
Q

What are the challenges of bonding and direct composites

A
  1. Polymerisation shrinkage

2. Achieving good contact points

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9
Q

What do we need to think about when looking at polymerisation shrinkage

A

The stress that it applies to the tooth composite interface

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10
Q

How much stress does polymerisation shrinkage apply to the tooth surface interface?

A

3-8MPa typically

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11
Q

How can we try and reduce the stress on a tooth

A

Look at the configuration factor of a cavity

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12
Q

What is the configuration factor of a cavity

A

(Number of bonded) divided by (number of unbonded surfaces)

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13
Q

What is the relationship between configuration fact and stress on the tooth?

A

As the configuration factor increases so does the stress on the tooth and leads to increased risk of polymerisation shrinkage

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14
Q

State the average percentage of shrinkage a typical composite restoration goes through

A

1.4-2%

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15
Q

What problems can arise if we create an insufficient contact point

A

Food packing can occur and it can be harder for the patient to clean the site

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16
Q

What can we do instead of placing a direct restoration to avoid polymerisation shrinkage and poor contact points

A

We can place an inlay

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17
Q

Is an inlay a direct or indirect restoration

A

Indirect

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18
Q

Define what an inlay is

A

An intra coronal restoration contracted in the lab and cemented into the tooth

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19
Q

How are good contact points achieved in an inlay?

A

The lab determines the fit and contours of the inlay

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20
Q

What problems can arise when using inlays?

A
  1. They require a taper which can create a wedging effect wearing the cusps
  2. Don’t cover the cusps so can’t provide cuspal protection
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21
Q

Why do inlays need to be tapered?

A

As they are placed into the tooth so need to be able to sit there properly

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22
Q

What is the issue with an inlay needing to have a taper

A

Risk of it having wedging affect so there might be forces directing downwards which can put stress and strain on the cusps (or even fracturing)

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23
Q

What should the height to base ratio be for an inlay to be successful?

A

Height to base less than or equal to 1

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24
Q

Talk through the indications for an inlay

A
  1. Small to medium cavity eg Small MO or DO cavities in molars and premoalrs
  2. Conservative MOD in molars
  3. Low caries rate
  4. Good support for cusps from remaining tooth tissue
  5. About 1/3rd buccal lingual width
  6. Height:base < 1:1
  7. Canine guidance
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25
Q

Are inlays commonly used in routine dentistry

A

No

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26
Q

When are inlays most useful?

A

When you have a large gap between adjacent teeth to achieve a good contact point

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27
Q

Give examples of restoration we can use that offer good cuspal protection

A
  1. Full coverage crowns

2. Onlays

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28
Q

List the principles of preparation

A
  1. Preservation of tooth tissue
  2. Retention and resistance form
  3. Structural durability of restoration
  4. Marginal integrity and position
  5. Biological
  6. Aesthetics
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29
Q

How much tooth tissue is removed when we place a full coverage crown?

A

67.5-75.6%

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30
Q

How much tooth tissue is removed when we place an onlay

A

39%

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31
Q

Do full coverage crowns or onlays achieve better retention and resistance

A

Full coverage crowns

32
Q

Define what an onlay is

A

A restoration constructed in the lab and cemented into a tooth that may contain an intracoronal aspect but also cabers one or more cusps

33
Q

Give some of the indications for onlays

A
  1. Teeth with larger restorations but sound buccal and lingual walls needing cuspal protection
  2. Low caries rate
  3. Weakened cusps
  4. Over 1/2 buccal lingual width
  5. Parafunciton
  6. Excessive cusp wear
  7. Group function
34
Q

Give examples of teeth that may need large restoration but have sound buccal and lingual walls that need cuspal protection

A
  1. Endodontically treated teeth
  2. Wider MODs
  3. MODs in premolars
35
Q

What materials can inlays and onlays be made up of?

A
  1. Gold
  2. Ceramic
  3. Composite
36
Q

What is the survival rate for a gold inlay or gold onlay

A

96% for 10 years

37
Q

What is the survival rate for a lithium dislocate onlay for 8 years??

A

100% for 8 years

38
Q

What is the survival rate for a ceramic inlay?

A

80% for 8 years

39
Q

Other than the lab where can ceramic inlays be made?

A

Using a CAD-CAM machine

40
Q

What are some problems associated with CAD-CAM inlays?

A

There have been instances of submargination and hypersensitivity

41
Q

List some of the factors that govern the choice of material we use to make our inlay/onlay

A
  1. Preservation of tooth tissue
  2. Retention and resistance form
  3. Structural durability of restoration
  4. Marginal integrity and position
  5. Biological considerations
  6. Aesthetics
42
Q

Which material is best to use if we want to preserve tooth tissue

A

Gold or a full coverage crown is best

Porcelain requires the most preparation

43
Q

Which material is best to use if we want to minimise damage to opposing enamel

A

Composite and gold have the least affect on opposing enamel

44
Q

Which material offers the best aesthetic finish

A

Ceramic or composite

45
Q

List some of the general preparation guidelines

A
  1. No undercuts
  2. Limited paths of insertion
  3. Resistance to occlusal forces
46
Q

How is retention achieved for inlays OR onlays to sit in the cavity?

A

As a result of friction between opposing intra coronal walls (this means the walls need to diverge)

47
Q

When we are creating a cavity what can naturally form?

A

An undercut

We DO NOT want his when placing an inlay or onlay

48
Q

How can we remove undercuts from out cavity prep

A
  1. Make our cavity bigger (NOT PREFERRED)
  2. We can restore the intracoronal aspect with composite and clock out the undercuts created naturally duding preparation
49
Q

How much taper do we want to achieve when creating a cavity for gold onlays

A

6 degree taper

50
Q

State the idea marginal width we want to achieve when creating a cavity for gold onlays

A

Chamfer of 0.5mm

51
Q

How much occlusal reduction do we need to do for a gold onlay?

A

1mm occlusal reduction for gold

1.5mm functional cusp bevel

52
Q

Talk through the preparation requirements needed for a gold onlay

A

Taper: 6degree
Marginal chamfer of 0.5mm
1mm occlusal reduction
1.5mm functional cusp bevel

53
Q

State the minimum width space requirement for a porcelain inlay/onlay

A
  1. 1.5-2mm width isthmus (1/3rd intercuspal width)
  2. 1.5-2mm depth
  3. 2mm occlusal coverage
54
Q

State the margin angles and chamfer needed for a composite or ceramic inlay/onlay

A

90-120 degree Cavo surface margin

Heavy chamfer/ rounded 1mm shoulder

55
Q

State the taper we need for a composite or ceramic inlay/onlay

A

15-20 degree taper

56
Q

Talk through the preparation requirements needed for a composite or ceramic inlay/onlay

A
  1. 1.5-2mm width isthmus
  2. 1.5-2mm depth
  3. 90-120 degree Cavo surface margins
  4. Heavy chamfer/ rounded 1mm shoulder
  5. 15-20 degree taper
  6. Rounded internal angles
57
Q

When creating our cavity what should we make sure in regards to preparation margins

A

Need to make sure they are not located in areas of static or dynamic antagonist contact

58
Q

How much taper an a lithium disilicate restoration have?

A

Upto 12 degrees

59
Q

What is the minimal width and occlusal reduction needed for a lithium disilicate restoration?

A

1mm minimal width and 1mm occlusal reduction

60
Q

What should the Cavo surface angle be for a lithium disilicate restoration?

A

100-120 degrees

61
Q

What is another name for adhesive onlays?

A

Table tops or occlusal veneers

62
Q

What materials are adhesive onlays usually made from?

A

Gold or lithium disilicate

63
Q

Describe the preparation needed for an adhesive onlay

A
  1. 0.5mm chamfer

2. 1.0 occlusal reduction

64
Q

How do adhesive onlays adhere to the tooth?

A

By a cement

65
Q

What is the benefit of adhesive onlays retaining onto the tooth via a cement?

A

Can achieve a more conservative preparation as the restoration doesn’t require any sort of intra coronal retention tool

66
Q

Give some indications for adhesive onlays

A
  1. Cuspal coverage for cracked tooth syndrome or protection
  2. Erosion or attrition
  3. Short or over tapered clinical crowns
  4. Patients with amelogenesis
67
Q

Give some of the contra indications of adhesive onlays

A
  1. Poor oral hygiene
  2. Subgingival margins
  3. Inability to gain good moisture isolation
  4. Lack of enamel margins
  5. Parafunction
68
Q

Before placing a metal adhesive onlay onto a tooth what must be done to it

A

It must be sandblasted on its fit surface

69
Q

What can be added to composite onlays to help improve the bonding?

A

A primer can be added onto the fit surface

70
Q

What can be added to ceramic onlays to help improve the bonding?

A

A silane coupler can be added onto the fit surface

71
Q

While the onlay or inlay is being prepared what do we need to do to the prepared tooth

A

We need to temporise the tooth with a temporary restoration

72
Q

After preparing your cavity for an inlay or onlay what do you need to do?

A

Take an impression of the preparation

73
Q

After your inlay or onlay has been created what do you need to do?

A

Cement it onto the tooth

74
Q

How are cast metal onlays and inlays retained in the tooth and name the cements you’d expect to use with these metals

A

Mechanical retention
Would see cements like:
1. Zinc phosphate
2. Glass ionomer luting cement

75
Q

Name the more modern way to adhere inlays or onlays to teeth

A

Adhesive retention is more modern

76
Q

Give examples of some adhesive cements

A
  1. Panavia F 2.0

2. Rely X ultimate

3rd Yr- CSB- Extra-coronal restorations (11 decks)

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