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Flashcards in Composite resins and glass-ionomers Deck (41)
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1

What are the benefits of composite amalgam

aesthetic, cured by visible light, ease of placement, compatible of the organic and inorganic mix of tooth

2

What are the two main components of composite?

an organic phase (resin) and inorganic phase (filler)

3

Are organic polymers or inorganic materials stronger?

inorganic = stronger and good processing
organic = tough (resistant to wear)

4

what are two ways to change cross-link density?

change the umber of cross-linking group and degree of cross-linking/curing

5

What are the three types of curing?

mixing (chemical), heat, light

6

What is characteristic of mixing curing?

operator dependent working time, no special tools, chairside

7

What is characteristic of heat curing?

consistent, high degree of cure, not good in vivo

8

What is characteristic of light curing?

command curve, good in vivo, low degree of cure, limited thickness

9

What are the components of a composite resin SYSTEM?

resin system, filler, bonding agent, and visible light initiator

10

What is the most common resin system?

BisGMA-TEGDMA
plus a structural component and diluent

11

What are the chains of the methylmethacrylate?

four distinct chains

12

What are the characteristics of polymer bonds?

covalent bonds, high MW, long and nonmetallic elements

13

How do polymers derive their strength and properties?

entanglement, like cooked spaghetti

14

What food is consistent with the viscosity of resin?

honey

15

Why is BisGMA used if its is so viscous?

it provides physical properties of composite filling

16

What is often used to make the BidGMA less thick?

TEGDMA at 30-50 wt %

17

What are the two usual fillers?

silica or zinc based inorganics

18

What wt percent is fillers of the composite filling?

50-80 wt %

19

What organic group is on the surface of fillers?

-OH

20

What are the three grades of fillers?

micron = fine
nano = microfine
nano in polymer matrix

21

Why would a smaller filler size be used?

teeth are nanocomposites, smaller fillers = better wear, allows for better polishing/finishing

22

What wt % of micron or fine particles can be used in composite?

77-88%

23

What wt % of nano filler can be used in composite?

MAX of 38 wt %

24

What wt % of nano filler in polymer can be used in composite?

50-60 wt %

25

What is characteristic of hybrid composites?

mixture of filler sizes with a loading of 70 wt %

26

What is characteristic of flowable composite?

thin, lower filler, low modulus, higher shrinkage

27

How is polymer shrinkage measured?

density changes

28

Why is polymerization shrinkage important?

direct composite restoratives and materials that require dimensional stability

29

What are some effects of polymer shrinkage?

Stress on tooth structure, microleaks, secondary carries

30

Is water sorption higher or lower in filled systems versus unfilled?

lower