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5th yr- Finals- CSB revision > Inlays and onlays > Flashcards

Inlays and onlays Flashcards

1
Q

What are some of the negative consequences 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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2
Q

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

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

How can we manage weakened cusps?

A
  1. Bonding
  2. Cusps coverage
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5
Q

What are the challenges of bonding and direct composites

A
  1. Polymerisation shrinkage
  2. Achieving good contact point
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6
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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7
Q

How can we try and reduce the stress on a tooth

A

Look t eat configuration factor of a cavity

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8
Q

What do we mean by configuration factor

A

(Number of bonded surfaces) / (number of unbounded surfaces)

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9
Q

What is the relationship between configuration factor and stress on the tooth

A

As the configuration fact increase so does the stress on the tooth increasing risk of polymerisation shrinkage

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10
Q

What problem can occur if we create an insufficient contact point

A

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

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11
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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12
Q

Define what an inlay is

A

An extra coronal restoration made in the lab and cemented into the tooth

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13
Q

What problems can arise when using inlays

A
  1. They require taper which can create a weeding effect wearing the cusps
  2. They down cover the cusps so can’t provide cuspal coverage
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14
Q

Why do inlays need to be tapered

A

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

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15
Q

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

A

Risk of having a wedging effect which will direct forces downward putting stress on the cusps leading to fracture

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16
Q

What shoddy the height to base ratio be for an inlay to be successful

A

heigh tot base ratio of lead than or equal to 1q

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17
Q

Talk through the indications of an inlay

A
  1. Small to medium cavity eg MO or DO
  2. Conservative MOD in molars
  3. Low caries risk
  4. Good support for cusps from the remaining tooth tissue
  5. About 1/3rd buccal lingual width
  6. Height base ratio < 1:1
  7. Canine guidance
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18
Q

When are inlays most useful

A

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

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19
Q

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

A
  1. Full coverage crowns
  2. Onlays
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20
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. Aesthetic
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21
Q

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

A

67.5-75.6%

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22
Q

How much tooth tissue is removed when we place an onlay

A

39%

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23
Q

What is an onlay

A

A restoration constructed in the lap and cemented into a tooth that may contain an intra coronal aspect but also covers one or more cusps

24
Q

Give some indications for onlays

A
  1. Teeth with larger restorations but sound buccal and lingual walls needing cuspal protection
    2, Low caries risk
  2. Weakened cusps
  3. Over 1/2 buccal lingual width
  4. Parafunciton
  5. Excessive cusp wear
  6. Group function
25
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
26
Q

What materials can inlays and onlays be made up of

A
  1. Gold
  2. Ceramic
  3. Composite
27
Q

What is the survival rate for a ceramic inlay?

A

80% for 8 years

28
Q

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

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

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

A

Gold or full coverage crown is best

30
Q

Which Materia requires the most tooth preparation

A

porcelain

31
Q

Which Materia offers the best aesthetic finish

A

Ceramic or composite

32
Q

List some general preparation guidelines

A
  1. No undercuts
  2. Limited paths of insertion
  3. Resistance to occlusal forces
33
Q

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

A

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

34
Q

How can we remove undercuts from our cavity prep

A
  1. Make the cavity bigger (not preferred)
  2. We can restore the intra coronal aspect with composite and block out the undercuts created naturally when prepping
35
Q

How much taper do we want to create when creating a cavity for a gold onlay

A

6 degree taper

36
Q

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

A

chamfer of 0.5mm

37
Q

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

A

1mm occlusal
1.5mm functional cusp bevel

38
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

39
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
40
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

41
Q

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

A

15-20 degree taper

42
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
43
Q

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

A

Need to make Sur they are not located in a areas of static or dynamic antagonise contact

44
Q

How much taper an a lithium disilicate restoration have?

A

upto 12 degrees

45
Q

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

A

1mm minimal width and 1mm occlusal reduction

46
Q

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

A

100-120 degrees

47
Q

What is another name for adhesive onlays

A

Table top s or occlusal veneers

48
Q

What materials are adhesive onlays usually made from

A

Gold or lithium disilicate

49
Q

Describe the preparation needed for an adhesive onlay

A

0.5mm chamfer
1mm occlusal reduction

50
Q

How do adhesive onlays adhere to the tooth

A

By a cement

51
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

52
Q

Give some indications for adhesive onlays

A
  1. Cuspal coverage for cracked tooth syndrome or protection
  2. Erosion or attrition
  3. Short or one tapered clinical crown
  4. Patients with amelogenesis
53
Q

Give some contra indication 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
54
Q

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

A

Must be sandblasted on its fit surface

55
Q

What can be added to composite onlays to help improve bonding

A

A primer can be added onto the fit surface

56
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 use cements like:
1. Zinc phosphate
2. Glass ionomer luting cement

5th yr- Finals- CSB revision (17 decks)

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