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
   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

Question 2

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

Answer 2

3 weeks

Question 3

What causes dentinal sensitivity

Answer 3

Exposure of dentinal tubules due to the removal of enamel

Question 4

Name the mechanism that describes how dentinal tubules lead to sensitivity

Answer 4

Hydrodynamic flow theory

Question 5

What is try consequence of teeth over erupted after preparation?

Answer 5

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

Question 6

Temporary crowns used to check aesthetics are termed as?

Answer 6

Provisional crowns

Question 7

What are the benefits of using provision crowns?

Answer 7

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

Question 8

What are temporary crowns used to prevent?

Answer 8

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

Question 9

What are temporary crowns used to restore

Answer 9

1. Aesthetics
2. Occlusion
3. Contact points

Question 10

List some ideal properties of a temporary crown

Answer 10

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

Question 11

Name the 3 main methods of manufacturing a temporary crown

Answer 11

1, Direct custom made

2. Prefabricated
3. Indirect lab made

Question 12

Name the most common method we use to manufacture temporary crowns

Answer 12

Direct chair side custom made technique

Question 13

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

Answer 13

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

Question 14

What is the trade name for bis acryl composite?

Answer 14

Integrity

Question 15

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

Answer 15

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

Question 16

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

Answer 16

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

Question 17

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

Answer 17

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

Question 18

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

Answer 18

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 19

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

Answer 19

Creating a diagnostic wax up

Question 20

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

Answer 20

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 21

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

Answer 21

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 22

Talk through the stages of using prefabricated temporary crowns

Answer 22

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 23

What are the benefits of using prefabricated temporary crowns

Answer 23

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

Question 24

What are the disadvantages of using prefabricated temporary crowns

Answer 24

Need to be adjusted to fit each individual tooth

Question 25

What are prefabricated temporary crowns for anterior teeth made from

Answer 25

Polycarbonate

Question 26

What are prefabricated temporary crowns for posterior teeth made from

Answer 26

Aluminium ion OR Stainless steel

Question 27

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

Answer 27

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

Question 28

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

Answer 28

Soft so can readily adapt to the patients occlusion

Question 29

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

Answer 29

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

Question 30

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

Answer 30

We use special BB crown shears to trim the margins | Reline with integrity to make sure the temporary fits the crown

Question 31

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

Answer 31

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

Question 32

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

Answer 32

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

Question 33

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

Answer 33

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 34

What are indirect lab made temporary restorations made from?

Answer 34

Acrylic materials (PMMA)

Question 35

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

Answer 35

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

Question 36

What does PMMA stand for

Answer 36

Poly methyl methacrylate

Question 37

Why can we not use PMMA chair side?

Answer 37

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

Question 38

What are advantages of PMMA

Answer 38

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

Question 39

What are disadvantages of PMMA

Answer 39

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

Question 40

Talk through the indirect lab technique of making temporary crowns

Answer 40

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 41

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

Answer 41

We need to cement it

Question 42

How do we cement temporary crowns

Answer 42

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

Question 43

When are non eugenol cements used?

Answer 43

For use when using resin cements for permanent crowns