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5th yr- Finals- CSB revision > 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
  3. To restore aesthetics between appointments
  4. To prevent dentinal sensitivity
  5. Protection from reinfection between appts
  6. To prevent unwanted tooth movement
  7. To test any changes we are making to aesthetics or occlusion
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2
Q

What causes dentinal sensitivity

A

Exposure of dentinal tubules due to the removal of enamel

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3
Q

Name the mechanism that describes how dentinal tubules lead to sensitivity

A

Hydro dynamic flow theory

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4
Q

What is the consequence of teeth over erupting after preparation

A

When you place the permanent crown it may sit high due to over eruption of the prepared tooth

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5
Q

What are temporary crowns used to check aesthetics called

A

provisional crowns

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6
Q

What are temporary crowns used to prevent

A
  1. Sensitivity of dentine
  2. Bacterial invasion of dentinal tibias
  3. over eruption and drifting of teeth
  4. Over growth of gingiva
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7
Q

What are temporary crowns used to restore

A
  1. Aesthetics
  2. Occlusion
  3. Contact points
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8
Q

List some ideal properties of a temporary crown

A
  1. Aesthetics
  2. Sufficient strength to be functional
  3. Restore contact points
  4. Accurate margins to prevent plaque accumulation
  5. Retentive but easy to remove when needed
  6. Biocompatitible
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9
Q

Name the 3 methods of manufacturing a temporary crown

A
  1. Direct custom made
  2. Pre fabricated
  3. Indirect lab made
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10
Q

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

A
  1. Make a mould o the tooth
  2. Crown prep
  3. Use the mould to make the temporary crown
  4. Let the composite set then you can remove it from the putty mould
  5. Remove any excess flash off the temp corn
  6. Cement the temporary crown with temporary cement
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11
Q

What do we use to make the temporary crown

A

Bis acryl composite - integrity

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12
Q

What are the 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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13
Q

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

A
  1. May have a granular finish
  2. Only 2 shade choices so won’t be a perfect match
  3. Poor stain resistance
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14
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
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15
Q

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

A

Creating a diagnostic wax up

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16
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

17
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

18
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
19
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
20
Q

What are the disadvantage of using prefabricated temporary crowns

A

Need to be adjusted to fit each individual tooth

21
Q

What are prefabricated temporary crowns for posterior teeth made from

A

Aluminium ion
OR
Stainless steel

22
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

23
Q

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

A

Soft so can readily adapt to the patients occlusion

24
Q

What are the disadvantages of using aluminium performed crowns for posterior teeth

A
  1. Margins can be sharp and irritant
  2. Poor contact points
  3. Poor aesthetics
  4. Metallic taste
25
Q

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

A

If we want the crown to last longer than three weeks these 2 methods will not work

26
Q

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

A

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

27
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

28
Q

What are indirect lab made temporary restorations made from?

A

Acrylic materials (PMMA)

29
Q

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

A
  1. More aesthetic
  2. Stronger
  3. More shades available
30
Q

What does PMMA stand for

A

Poly methyl methacrylate

31
Q

Why can we not use PMMA chair side?

A

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

32
Q

What are advantages of PMMA

A
  1. Good marginal fit
  2. Good strength
  3. Can be polished
  4. Durable
33
Q

What are disadvantages of PMMA

A

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

34
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
35
Q

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

A

We need to cement it

36
Q

How do we cement temporary crowns

A

Using
1. Fine particle zinc oxide eugenol cement
2. Non eugenol cements

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

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