temporary crowns:

Question 1

why do we need temporary crowns

Answer 1

labs take 3 weeks to make a crown so we need something to protect the tooth

Question 2

list some reasons why temporary crowns are needed

Answer 2

restore aesthetics and function 
prevent dentinal sensitivity
prevent tooth drifting 
pt can change aesthetics or occlusion
prevent gingival overgrowth 
restore contact points

Question 3

what do we need to do If the tooth has drifted

Answer 3

we would need to reprep the tooth

Question 4

what are the ideal properties of the temporary crown

Answer 4

○ Aesthetics
○ Sufficient strength to be functional
○ Restore contact points
○ Accurate margins to prevent plaque accumulation
○ Retentive but easily removed when needed
Biocompatible

Question 5

what are some main manufacture methods of temporary crowns

Answer 5

direct custom made
prefabricated
indirect lab made

Question 6

how do we make a temp crown chair side

Answer 6

1) Make a mould of the tooth
2) Crown prep
3) And use the mould we used originally to make the temp crown( use integrity( bis acryl composite) on clinic
4) When set remove the mould and remove the flash
Using a temp cement( temp bond Zinc oxide eugenol cement)

Question 7

what is the benefit of bisacryl composite

Answer 7

has adequate strength
accurate fit
no mixing required

Question 8

indications of direct chair side technique

Answer 8

We can use this technique when the tooth that needs a crown is a poor shape to start off with
Or when we want to change the shape of the tooth

Question 9

indications of prefabricated temp crown

Answer 9

use the technique when the tooth is not the shape we want it to be eg directa crown

Question 10

advantages of prefabricated temporary crown

Answer 10

Comes ready made
Needs to be adjusted to fit each tooth
Usually hard wearing materials
Durable

Question 11

what can we use for posterior teeth

Answer 11

aluminium ion

stainless steel

Question 12

what is advantages of aluminium ion/stainless steel

Answer 12

Readily adapted to occlusion

Margin can be sharp and irritant- BB crown shears can be used to trim and shape

Question 13

disadvantages of aluminium ion/stainless steel

Answer 13

Poor contact points
Poor aesthetics
Metallic tasting

Question 14

how are indirect lab made techniques made

Answer 14

Will last much longer than 3 weeks- 4weeks
Made in the lab on a model
Made by lab tech using acrylic materials (PMMA)
Acrylic materials are stronger and more aesthetic than chairside

Question 15

how does the polymerisation of the indirect lab made technique might cause damage

Answer 15

highly exothermic and there is a large degree of shrinkage

Way over 100 degrees- not suitable for direct use in the mouth

Question 16

advantages of indirect lab made crowns

Answer 16

Good marginal fit
Good strength
Can be polished
Durable

Question 17

how does cementation of an indirect lab crown occur

Answer 17

Requirements of a temp cement
Strong enough to retain the crown for the period of temporisation
Allows easy removal when required
Doesn’t adhere to the tooth

Question 18

what cement do we use for indirect lab crown

Answer 18

ZnOE( zinc oxide eugenol cements

On the clinics is called tempbond

Question 19

when might we use non eugenol cements

Answer 19

if using resin cements for permanent crowns

Question 20

why might we need to be careful of eugenol

Answer 20

allergies