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3rd Yr- CSB- Extra-coronal restorations > Temporary Crowns > Flashcards

Temporary Crowns Flashcards

1
Q

Why do we need temporary crowns?

A
  1. To protect the tooth before permanent crown is made
  2. Temporarily bring it back to function between appointments
    To restore aesthetics between appointments
  3. To prevent dentinal sensitivity
  4. Protection from reinfection between appointments
  5. To prevent unwanted tooth movement
  6. To test any changes we are making to aesthetics or occlusion
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2
Q

How long does it take for a permanent crown to be made in the LDI?

A

3 weeks

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3
Q

What causes dentinal sensitivity

A

Exposure of dentinal tubules due to the removal of enamel

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4
Q

Name the mechanism that describes how dentinal tubules lead to sensitivity

A

Hydrodynamic flow theory

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5
Q

What is try consequence of teeth over erupted after preparation?

A

When you place you permanent crown it may not sit right (may sit too high) due to over eruption of the prepared tooth

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6
Q

Temporary crowns used to check aesthetics are termed as?

A

Provisional crowns

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7
Q

What are the benefits of using provision crowns?

A

If you are modifying the aesthetics of the tooth the patient get an almost taster session of how they will look once the permanent crown has been placed
This gives the patient enough time to decide if they like the restoration or not

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8
Q

What are temporary crowns used to prevent?

A
  1. Sensitivity of dentine
  2. Bacterial invasion of denial tubules
  3. Over eruption and drifting of teeth
  4. Overgrowth of gingiva
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9
Q

What are temporary crowns used to restore

A
  1. Aesthetics
  2. Occlusion
  3. Contact points
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10
Q

List some ideal properties of a temporary crown

A
  1. Aesthetic
  2. Sufficient strength to be functional
  3. Restore contact points
  4. Accurate margins to prevent plaque accumulation
  5. Retentive BUT easily removed when needed
  6. Biocompatible
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11
Q

Name the 3 main methods of manufacturing a temporary crown

A

1, Direct custom made

  1. Prefabricated
  2. Indirect lab made
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12
Q

Name the most common method we use to manufacture temporary crowns

A

Direct chair side custom made technique

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13
Q

Talk through the direct chair side custom made technique of temporary crown making

A
  1. Make a mould of the tooth
  2. Crown prep
  3. Use the mould to make the temporary crown: place bis acryl composite into the mould
  4. Let the composite set then you can remove it from the putty mould
  5. Remove any excess (flash) of the temporary crown
  6. Cement the temporary crown with temporary cement
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14
Q

What is the trade name for bis acryl composite?

A

Integrity

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15
Q

What are the benefits of using bis acryl composite for making a temporary crown

A
  1. Adequate strength
  2. Accurate fit
  3. No mixing required
  4. Acceptable aesthetics
  5. Choice of 2 shades
  6. Can repair with composite
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16
Q

What are the disadvantages of bis acryl composite for making a temporary crown

A
  1. May have a granular finish (can be resolved by polishing)
  2. Only 2 shade choices so won’t be a perfect match
  3. Poor stain resistance
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17
Q

What is the disadvantage of the the chair side direct custom made technique?

A
  1. What is the tooth that needs the crown is in poor shape to start with
  2. What if if want to change the shape of the teeth
    We cannot use a mould in these scenarios as we want a different finishing
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18
Q

Talk through the stages of the direct lab made technique for making temporary crowns

A
  1. Take a mould of the teeth and send this mould to the lab
  2. The lab can then produce an ideal tooth shape which can now be used as the template
  3. Crown prep
  4. Lab can make an index for the whole arch using PVC material
  5. Use the mould to make the temporary crown: place bis acryl composite into the mould and Let the composite set then you can remove it from the putty mould
  6. Remove any excess (flash) of the temporary crown
  7. Cement the temporary crown with temporary cement
19
Q

Asking the lab to produce an ideal tooth shape from a mould is called what?

A

Creating a diagnostic wax up

20
Q

What are trey benefits of the lab making a vinyl PVC mould of the entire arch?

A

It is easy to use and is permanent so if patient comes again and needs another tooth crowned we already have the perfect model ready to make the temporary crown

21
Q

What is the disadvantage of the direct lab made technique for making temporary crowns

A

When removing the excess flash of the temporary crown you need to do it in the mouth and the excess can get trapped in the undercuts of the mouth and can be difficult to remove once the composite has gotten hard

22
Q

Talk through the stages of using prefabricated temporary crowns

A
  1. Crown preparation
  2. Select crown from range of sizes
  3. Customise the prefabricated temp crown to fit the tooth accurately by using the integrity
23
Q

What are the benefits of using prefabricated temporary crowns

A
  1. Come ready made
  2. usually made of a hard wearing material
  3. Durable
24
Q

What are the disadvantages of using prefabricated temporary crowns

A

Need to be adjusted to fit each individual tooth

25
Q

What are prefabricated temporary crowns for anterior teeth made from

A

Polycarbonate

26
Q

What are prefabricated temporary crowns for posterior teeth made from

A

Aluminium ion
OR
Stainless steel

27
Q

When picking a prefabricated temporary crown what do we look for?

A

We look to see which size fits the width of the tooth best as we can adjust the height using burs

28
Q

What are the benefits of using aluminium preformed crowns for posterior teeth?

A

Soft so can readily adapt to the patients occlusion

29
Q

What are the disadvantaged of using aluminium preformed crowns for posterior teeth?

A
  1. Margins can be sharp and irritant
  2. Poor contact points
  3. Poor aesthetics
  4. Metallic taste
30
Q

How do we adjust the size of aluminium preformed crowns for posterior teeth?

A

We use special BB crown shears to trim the margins

Reline with integrity to make sure the temporary fits the crown

31
Q

What are the disadvantages of the direct custom made and prefabricated crown methods?

A

If we want the crown to last longer Thant tree weeks these 2 methods will not work

32
Q

When do we use the indirect lab technique to make temporary crowns

A

Used if we want longer lasting temporary crown (3-4weeks)

33
Q

When would we want the temporary crown to last longer than 3 weeks?

A

When we are doing perio treatment on a patient and we are accepting their gingival margin to significant change so we would wait till the perio treatment is done before placing a permanent restoration

34
Q

What are indirect lab made temporary restorations made from?

A

Acrylic materials (PMMA)

35
Q

What are the benefits of using acrylic materials to make temporary crowns

A
  1. More aesthetic
  2. Stronger
  3. More shades available
36
Q

What does PMMA stand for

A

Poly methyl methacrylate

37
Q

Why can we not use PMMA chair side?

A

As it is highly exothermic and has a large degree of shrinkage

38
Q

What are advantages of PMMA

A

a1. Good marginal fit
2. Good strength
3. Can be polished
4. Durable

39
Q

What are disadvantages of PMMA

A

Not suitable for direct use in the mouth as it is highly exothermic

40
Q

Talk through the indirect lab technique of making temporary crowns

A
  1. Technician starts with a pre operative plaster model of the tooth
  2. A minimal prep is carried out on the model and the crown is made with heat cured PMMA
  3. Temp is returned to the clinical who prepared the tooth and then modifies the lab made temporary to make ti fir
41
Q

After we are happy with the temporary crown what do we need to do?

A

We need to cement it

42
Q

How do we cement temporary crowns

A

Using

  1. Fine particle zinc oxide eugenol cement
  2. Non eugenol cements
43
Q

When are non eugenol cements used?

A

For use when using resin cements for permanent crowns

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

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