Temporary Materials

Question 1

3 common temporary materials

Answer 1

PMMA
PEMA
Bis-acryl composite

Question 2

fabrication for PMMA

Answer 2

indirect

Question 3

fabrication for PEMA

Answer 3

direct/chairside

Question 4

fabrication for bis-acryl composite

Answer 4

direct/chairside

Question 5

duration for PMMA

Answer 5

long term

Question 6

duration for PEMA

Answer 6

short term

Question 7

duration for Bis-acryl composite

Answer 7

long term

Question 8

PMMA for crown / bridge?

Answer 8

short and long

Question 9

PEMA for crown / bridge?

Answer 9

singe crown

Question 10

Bis-acryl composite for crown / bridge?

Answer 10

short span bridges

Question 11

PMMA is

Answer 11

PolyMethylMethAcrylate (PMMA) eg Jet

Question 12

PEMA is

Answer 12

PolyEthylMethAcrylate (PEMA) eg Trim II, Snap

Question 13

Bis-acryl composite e.g.

Answer 13

Protemp4, Quicktemp

Question 14

UDMA is

Answer 14

UrethaneDiMethAcrylate (UDMA) eg Provipont DC

Question 15

feature of methacrylate monomer

Answer 15

NOTICE the single double bond next the CH2

CH2 = C(CH2)(COOCH3)

Question 16

reaction of methacrylate monomer

Answer 16

Free radical addition polymerisation of methacrylate monomer

Polymethacrylate (PMMA)
- forms a long chain molecule PMMA

There can be hundreds of methacrylate monomer molecules bonded together

Question 17

Jet is

Answer 17

temporary material product

PMMA

Question 18

Jet (PMMA) properties

Answer 18

Powder/liquid formulation
Self-curing
Good marginal fit
Good transverse strength
Polishable

But

poor abrasion resistance
high shrinkage
high thermal release
free monomer may be toxic

Question 19

PMMA is a

Answer 19

mono-functional monomer (i.e. one C=C double bond)

linear chain like polymer

Question 20

PEMA is

Answer 20

trim II, snap

based on ethyl methacrylate monomer

Question 21

bis-acryl(ate) composite is

Answer 21

e.g ProTemp4, Quicktemp

bis-GMA monomer

bifunctional (i.e. 2 C=C bonds)
- 3D polymer network

Question 22

urethane dimethacrylate e.g.

Answer 22

Provipoint DC

Question 23

chemistry of temporary materials

Answer 23

polymerisation reaction

powder/liquid or 2 pastes (cartridge system)

then can be mixed and shaped to requirements

Question 24

2 sources of information for DMS

Answer 24

Journals
- peer-reviewed
- trustworthy!
Product literature*
- detailed
- objective?
*common way for a GDP to assess products – though DATA is not always complete, NOR accurate!

Question 25

types of DMS product literature

Answer 25

Brochures

• superficial
• “positive” presentation
• sales oriented

Web-sites
- info-rich – not always relevant re properties

Product profile
- scientific info…but not definitive!
- not often supplied for products
Eg 3M ESPE, Heraeus…

Question 26

assessment of DMS

use (2 factors)

Answer 26

Quality of data
- in-house – biased potentially, commercially driven
- independent
(single study; review (may be out of date))

Competitive performance
- are rival products compared?

Question 27

2 key properties to assess for temporary materials

Answer 27

temperature

colour stability

Question 28

temperature importance in temporary materials

Answer 28

exothermic reaction

material encapsulates tooth prep

safety - DENTIST’S concern
- Need to be clinically harmless
- too much heat will potentially harm the dental pulp
safety issue, as pulp damage is to be avoided

Question 29

colour stability importance in temporary materials

Answer 29

reason for the provisional is to protect eg crown prep. And the end goal is for an aesthetic replacement of the natural tissue.

Aesthetics
- Anterior teeth
PATIENT’s concern

Question 30

temperature and dental safety

Answer 30

Link between thermal and pulpal damage

• duration
• temperature rise - bellow 11 is better

Clinical and histological evaluation of thermal injury to pulp

Question 31

colour stability and temporary materials

Answer 31

Will the material remain aesthetic during its lifetime - which may be several months.

Coffee test:

• After three days immersed in coffee at 36° C,
• measure objectively with colorimeter

change in appearance is measured by the delta E value.
The chart shows ΔE for PROTEMP is 1.5, for Integrity it’s 1.6. And with the highest values we have TRIM and JET at 10.9 and 21 units of ΔE.

Question 32

why is polymerisation shrinkage important for temporary materials

Answer 32

important for assessing a temporary material’s accuracy of fit

low polymerization shrinkage gives good clinical fit of the temporary restoration

can also measure marginal discrepancy

Question 33

what does marginal discrepancy assess

Answer 33

polymerisation shrinkage

what sort of gap forms at the tooth-material interface?

Question 34

why is compressive strength important for IM

Answer 34

TM has to withstand biting forces - as a permanent restorative material would.

Question 35

more the material abrades

Answer 35

the more likely that a SURFACE NOTCH will be created
- plaque trap, rough sensation to patient’s tongue

more abrade = weaker compressive strength

Question 36

other factors to consider when assessing TMs

Answer 36

Surface roughness (appearance)

ease of use

working and setting time

Question 37

key properties required for TM (always look for when assessing product)

Answer 37

temperature reached during setting (thermal release);

compressive strength

colour stability

abrasion resistance

polymerisation shrinkage