Temporary crowns

Question 1

Why do we need temporary crowns

Answer 1

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

Question 2

What causes dentinal sensitivity

Answer 2

Exposure of dentinal tubules due to the removal of enamel

Question 3

Name the mechanism that describes how dentinal tubules lead to sensitivity

Answer 3

Hydro dynamic flow theory

Question 4

What is the consequence of teeth over erupting after preparation

Answer 4

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

Question 5

What are temporary crowns used to check aesthetics called

Answer 5

provisional crowns

Question 6

What are temporary crowns used to prevent

Answer 6

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

Question 7

What are temporary crowns used to restore

Answer 7

1. Aesthetics
2. Occlusion
3. Contact points

Question 8

List some ideal properties of a temporary crown

Answer 8

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

Question 9

Name the 3 methods of manufacturing a temporary crown

Answer 9

1. Direct custom made
2. Pre fabricated
3. Indirect lab made

Question 10

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

Answer 10

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

Question 11

What do we use to make the temporary crown

Answer 11

Bis acryl composite - integrity

Question 12

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

Answer 12

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

Question 13

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

Answer 13

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

Question 14

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

Answer 14

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

Question 15

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

Answer 15

Creating a diagnostic wax up

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

Talk through the stages of using prefabricated temporary crowns

Answer 18

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

Question 19

What are the benefits of using prefabricated temporary crowns

Answer 19

1. Come ready made
2. Usually made of a hard wearing material
3. Durable

Question 20

What are the disadvantage of using prefabricated temporary crowns

Answer 20

Need to be adjusted to fit each individual tooth

Question 21

What are prefabricated temporary crowns for posterior teeth made from

Answer 21

Aluminium ion
OR
Stainless steel

Question 22

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

Answer 22

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

Question 23

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

Answer 23

Soft so can readily adapt to the patients occlusion

Question 24

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

Answer 24

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

Question 25

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

Answer 25

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

Question 26

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

Answer 26

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

Question 27

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

Answer 27

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

Question 28

What are indirect lab made temporary restorations made from?

Answer 28

Acrylic materials (PMMA)

Question 29

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

Answer 29

1. More aesthetic 2. Stronger 3. More shades available

Question 30

What does PMMA stand for

Answer 30

Poly methyl methacrylate

Question 31

Why can we not use PMMA chair side?

Answer 31

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

Question 32

What are advantages of PMMA

Answer 32

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

Question 33

What are disadvantages of PMMA

Answer 33

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

Question 34

Talk through the indirect lab technique of making temporary crowns

Answer 34

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

Question 35

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

Answer 35

We need to cement it

Question 36

How do we cement temporary crowns

Answer 36

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