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5th yr- Finals- CSB revision > Principles of tooth prep > Flashcards

Principles of tooth prep Flashcards

1
Q

What do we mean by indirect restoration

A

A restoration which is not placed directly into the patients mouth but crafted outside of the mouth

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2
Q

Give examples of indirect restorations

A
  1. Crown
  2. Porcelain veneer
  3. Only
  4. Inlay
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3
Q

What are indirect restorations important

A
  1. Improve aesthetics
  2. Comfort
  3. Improved function
  4. Increased stability
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4
Q

What are some fo the disadvantages of an indirect restoration

A

1 More tooth prep required
2. Take more Time
3. Multiple appointments

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5
Q

Why do we need to prepare teeth for an indirect restoration

A

To create space to create the restoration

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6
Q

What do we not want to create when preparing a tooth and why

A

An undercut as it results in over preparation and weakening of the tooth
this cute the teeth at higher risk of fracture an increase risk of locking impression material

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7
Q

What is an undercut

A

When the top of the tooth is wider than the bottom

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8
Q

What do we aim to create when preparing teeth

A

A single taper ensuring the widest portion of the tooth is at the bottom and the narrowest at the top

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9
Q

As well as the tooth you are preparing what else do you need to keep in mind and why

A

The adjacent teeth and the proximal contacts for the tooth you are preparing
This is t ensure you have an easy path of entry

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10
Q

What are we aiming for when considering the proximal contacts of the tooth we are preparing?

A

Ideally the proximal contacts should be parallel to the path of insertion

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11
Q

List the 7 principles of preparation

A
  1. Preservation of tooth tissue
  2. Retention and resistance
  3. Structural durability of the restoration
  4. Material choice
  5. Marginal integrity and position
  6. Biological considerations
  7. Aesthetics
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12
Q

What balance do we need to maintain when preparing a tooth

A

Need to balance taking enough tooth tissue to allow space for the restoration while also retaining as much as possible to protect the pulp to reduce fracture risk

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13
Q

What can happen if a tooth is under prepared

A
  1. Inadequate space for restoration
  2. Need to use thinner restorative material increasing risk of fracture and perforation
  3. If thicker material is used conforming to occlusion may be difficult resulting in a high spot on the restoration
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14
Q

What will happen if there is under peroration of the should/ chamfer near the cervical margin of a tooth

A

Material may chip or fracture scooping tooth tissue

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15
Q

What are the problems associated with over preparation

A
  1. Working closer to the pulp increasing risk of loss of vitality
  2. Increased risk of tooth fracture
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16
Q

State the 2 Rs of preparation

A

Resistance and retention

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17
Q

What is retention

A

Prevention the removal of an extra coronal restoration along the path of insertion

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18
Q

What is resistance

A

Preventing dislodgement by lateral or apical forces under occlusal load

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19
Q

What are the properties of retention and resistance influenced by

A
  1. Taper
  2. Surface area
  3. Height
  4. Preparation design
  5. Cement selection
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20
Q

What is the relationship between taper and resistance and retention

A

The greater the taper the less retention and resistance

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21
Q

How an internal surfaces be used to offer retention

A

Opposing surfaces contribute and the more parallel sided they are the greater the retention

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22
Q

What do we need to keep in mind when creating a taper

A

We need to be able to get the restoration in and out the cavity

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23
Q

What is the acceptable degree of taper on clinic

A

6-12 degrees

24
Q

What does a taper of 6-12 mean

A

It means there is a reduction of between 3 and 6 on the circumference of the tooth

25
Q

List the characteristics of an optimal taper

A
  1. Preserve tooth tissue
  2. Provide good resistance and retention
  3. Allow visible finish line
  4. Allow adequate seating of an indirect restoration
  5. Aim for taper between 6-12 degrees
26
Q

Other than taper what else do we need to consider

A

Surface area
Height

27
Q

What is the relationship between surface area and resistence and retention

A

The greater the surface area the greater the retention and resistance

28
Q

What is the relationship between height retention and resistance

A

The greater the height the greater the retention dn resistance

29
Q

What preparation designs can we add to aid retention and resistance

A

Grooves and boxes

30
Q

Where are grooves placed and what do they aid

A

They are placed along the path of insertion aiding resistance

31
Q

Name the 2 categories of cement we can choose from to cement an indirect restoration

A

passive and agressive

32
Q

What does the structure of an indirect restoration need to be able to withstand

A
  1. Occlusal forces
  2. Oral environment and changes in temp and pH
  3. Mastication of food
33
Q

What are the problems associated with using thin porcelain

A

It is prone to cracks and fractures

34
Q

What are the problems associated with using thin metal

A

May perforate

35
Q

List some materials we cause to make an indirect restoration

A
  1. Metal ceramic
  2. Gold
  3. Non precious metals
  4. All ceramic
36
Q

Name the three types of margin designs we can make

A
  1. Chamfer
  2. shoulder
  3. Kinfe edge
37
Q

When is a shoulder margin used

A

For metal ceramic crowns

38
Q

What thickness shoulder do we need for an MCC

A

At least 1.2mm

39
Q

When is a chamfer margin used

A

For gold crowns

40
Q

What thickness do we require our chamfer margins to be

A

0.5mm

41
Q

What thickness do we require our chamfer margins to be

A

0.5mm

42
Q

Where is the margin placed on the labial side of a tooth?

A

As aesthetics are key often placed level with the gingiva or slightly into the gingival sulcus

43
Q

What is the problem with placing a margin level with the gingiva and how do we overcome this problem?

A

Makes maintenance difficult and so impression may require a retraction cord

44
Q

What is the ideal position to finish a margin

A

On sound tooth tissue if feasible

45
Q

What are the problems with taking a margin sub gingival

A

Can compromise the gingival health

46
Q

What are the problems with the margin being inline with the gingiva

A

Can compromise aesthetics

47
Q

What are the problems with the margin being supra gingival

A

Can compromise aesthetics

48
Q

What do we NEED to preserve when preparing a tooth for an indirect restoration?

A

NEED to persevere the periodontium

49
Q

What can we do to persevere the periodontium ?

A
  1. Make sure patient has good oral hygiene
  2. Make a supra gingival margin
  3. Make sure there’s a sufficient marginal reduction with no over hangs or PRF
50
Q

On top of the periodontium what else do we need to take of when placing an indirect restoration?

A

Need to protect the soft tissues and look at the biological width

51
Q

What is the biological width

A

The distance from the depth of the sulcus to the crest of alveolar bone

52
Q

What does the biological width include

A

The junctional epithelium and the connective tissue attachment

53
Q

What effect can impressions and indirect restoration placement have on the soft tissues

A

Can lead to persistent gingival inflammation

54
Q

How many teeth become non vital after crown prep

A

1 in 5

55
Q

What biological consideration must be made when preparing indirect restoration

A
  1. Preserve the periodontium
  2. Preserve the pulp
  3. Protect soft tissues
  4. Consider crown length
56
Q

How can we protect the pulp when carrying out preparations

A

Retain as much mineralised tissue as possible and avoid excessive reduction which approaches the pulp tissue

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

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