Temporary Materials

Question 1

What are the different types of temporary materials

Answer 1

PMMA eg jet
PEMA e.g trim II
Bis-acryl composite e.g protemp
UDMA e.g provipont DC

Question 2

Is PMMA a direct or indirect material

Answer 2

indirect

Question 3

Is PEMA a direct or indirect material

Answer 3

direct/chairside

Question 4

Is bis-acryl composite a direct or indirect material

Answer 4

direct

Question 5

What is the duration of PMMA material

Answer 5

long term

Question 6

What is the duration of PEMA material

Answer 6

short term

Question 7

What is the duration of bis-acryl composite

Answer 7

long term

Question 8

Is PMMA used for crowns and bridges

Answer 8

short and long span bridges

Question 9

Is PEMA used for crowns and bridges

Answer 9

single crowns

Question 10

Is bis-acryl composite used for crowns and bridges

Answer 10

short span bridges

Question 11

What is the monomer that makes up PMMA

Answer 11

mono functional monomer

methacrylate monomer

Question 12

What are the features of PMMA

Answer 12

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 13

How is PMMA formed

Answer 13

the mono functional monomer with one C=C double bond forms a linear chain-like polymer

Question 14

How is bis-acrylate composite form

Answer 14

from a bis-GMA monomer
bifunctional (2 C=C double bound)
forms a 3D polymer network

Question 15

How are all the temp materials formed

Answer 15

polymerisation

powder/liquid or 2 pastes (cartridge system)

Question 16

What are the sources of scientific information on materials

Answer 16

journals & product literatures

Question 17

What is the issue with product literature

Answer 17

data is not always complete or accurate

Question 18

What can product literature be

Answer 18

brochures
websites
product profiles

Question 19

What are the issue with brochures

Answer 19

made to sell products
superficial
give a positive presentation

Question 20

What is the issue with websites

Answer 20

it is information rich but this means it takes time to sift through information
it is not always the relevant properties

Question 21

What is the issue with product profile

Answer 21

scientific info but not definitive

not often supplied for products

Question 22

When we do an assessment what do we look at

Answer 22

quality of data

competitive performance

Question 23

What do we look at when looking at quality of data

Answer 23

is the data in house (by manufacturers) or independent

Question 24

What are key properties that are of dentists concern

Answer 24

temperature of exothermic reaction

material encapsulates tooth prep

safety

Question 25

What are key properties that are of px concern

Answer 25

aesthetics | ant. teeth

Question 26

Why is temperature a safety issue

Answer 26

there may be a link between thermal change and pulp damage

Question 27

What approach did Zach and Cohen use

Answer 27

thermal stimulus applied to teeth using soldering ion and crude and a thermostat was used to record the temperature of the inner tooth surface of pulp chamber

Question 28

What were Zach and Cohens findings

Answer 28

2 degrees increase - no effect on pulp histology of controls 5.5 degrees increase - significant tissue changes over first few days, after 56 days most pulps had overcome thermal trauma but some pulps of smaller teeth were necrotic 11 degrees increase - most (two thirds) suffer irreparable necrosis

Question 29

What was the missing factors from Zach and Cohens findings

Answer 29

pulpal damage is also affected by duration of the temperature rise experienced

Question 30

What did Tjan's study show

Answer 30

temp taken during fabrication of provisional crown amount of heat transferred to pulp chamber during polymerization of resins may be sufficient to cause thermal damage to the dental pulp and odontoblasts

Question 31

Why should Tjan's results be taken with caution

Answer 31

in vitro study | doesn't identify biological environment

Question 32

What did Baldissara's study show

Answer 32

it contradicts the study that a temperature rise of 11.5 degrees will cause pulp tissue damage

Question 33

What was the baldissara experiment protocol

Answer 33

use a pair of teeth belonging to same individual

Question 34

What is the experiment for baldissara

Answer 34

one tooth was exposed to the thermal stimulus believed to be harmful (symptomatically monitored from 68 to 91 days). extracted and examined histologically to identify possible signs of damage to the pulp second tooth is extracted and exposed to same thermal stimulus as tooth 1. in order to assess the temperature increase induced in tooth 1 (in vitro) i.e record temperature profile applied

Question 35

What did baldissara results suggest

Answer 35

that an increase of 11 degrees will not damage the pulp as there is no signs of inflammation and no reparative processes at higher temperature

Question 36

Are any materials above 11 degrees temp change

Answer 36

no | duration also significant

Question 37

How is color stability measured

Answer 37

coffee test - 3 days immersion in coffee at 36 degrees pro temp 4 is best also objective measure - colorimeter measure in detail, lowest for pro temp

Question 38

What was significant about colors stability of pro temp

Answer 38

objective measure showed it was not as good as coffee test

Question 39

Why is polymerization shrinkage significant

Answer 39

important for assessing a temp materials accuracy of fit low PS gives good clinical fit of temp restoration

Question 40

Which materials have lowest shrinkage

Answer 40

pro temp and integrity

Question 41

Which materials have highest compressive strength

Answer 41

pro temp 560 newton forces but biting can reach 700 newtons

Question 42

What material is most resistant material

Answer 42

luxatemp and pro temp much less resistant than amalgam still

Question 43

Why is surface roughness significant

Answer 43

influences appearance

Question 44

Which material has lowest surface roughness

Answer 44

luxatemp | protemp 3 grant

Question 45

What are other important factors

Answer 45

ease of use | working and setting time