Composite resins and glass-ionomers

Question 1

What are the benefits of composite amalgam

Answer 1

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

Question 2

What are the two main components of composite?

Answer 2

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

Question 3

Are organic polymers or inorganic materials stronger?

Answer 3

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

Question 4

what are two ways to change cross-link density?

Answer 4

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

Question 5

What are the three types of curing?

Answer 5

mixing (chemical), heat, light

Question 6

What is characteristic of mixing curing?

Answer 6

operator dependent working time, no special tools, chairside

Question 7

What is characteristic of heat curing?

Answer 7

consistent, high degree of cure, not good in vivo

Question 8

What is characteristic of light curing?

Answer 8

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

Question 9

What are the components of a composite resin SYSTEM?

Answer 9

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

Question 10

What is the most common resin system?

Answer 10

BisGMA-TEGDMA

plus a structural component and diluent

Question 11

What are the chains of the methylmethacrylate?

Answer 11

four distinct chains

Question 12

What are the characteristics of polymer bonds?

Answer 12

covalent bonds, high MW, long and nonmetallic elements

Question 13

How do polymers derive their strength and properties?

Answer 13

entanglement, like cooked spaghetti

Question 14

What food is consistent with the viscosity of resin?

Answer 14

honey

Question 15

Why is BisGMA used if its is so viscous?

Answer 15

it provides physical properties of composite filling

Question 16

What is often used to make the BidGMA less thick?

Answer 16

TEGDMA at 30-50 wt %

Question 17

What are the two usual fillers?

Answer 17

silica or zinc based inorganics

Question 18

What wt percent is fillers of the composite filling?

Answer 18

50-80 wt %

Question 19

What organic group is on the surface of fillers?

Answer 19

-OH

Question 20

What are the three grades of fillers?

Answer 20

micron = fine
nano = microfine
nano in polymer matrix

Question 21

Why would a smaller filler size be used?

Answer 21

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

Question 22

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

Answer 22

77-88%

Question 23

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

Answer 23

MAX of 38 wt %

Question 24

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

Answer 24

50-60 wt %

Question 25

What is characteristic of hybrid composites?

Answer 25

mixture of filler sizes with a loading of 70 wt %

Question 26

What is characteristic of flowable composite?

Answer 26

thin, lower filler, low modulus, higher shrinkage

Question 27

How is polymer shrinkage measured?

Answer 27

density changes

Question 28

Why is polymerization shrinkage important?

Answer 28

direct composite restoratives and materials that require dimensional stability

Question 29

What are some effects of polymer shrinkage?

Answer 29

Stress on tooth structure, microleaks, secondary carries

Question 30

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

Answer 30

lower

Question 31

Why do composites fail?

Answer 31

fracture or secondary caries

Question 32

What is characteristic of glass-ionomer cement?

Answer 32

cured by acid-base reaction, releases fluoride, good adhesion to the tooth

Question 33

What are the two major components of glass-ionomer cement?

Answer 33

Acid polymer in aqueous solution | basic glass

Question 34

What are the specific components of glass-ionomer cement?

Answer 34

polyacid basic glass water modifiers (+) tartaric acid

Question 35

What is characteristic of basic glass?

Answer 35

aluminafluorosilicate glass | the components are melted, cooled, and ground

Question 36

Describe the setting reaction of glass-ionomer

Answer 36

``` the polyacid reacts with basic glass (not all consumed) salt bridges form clears smear layer and leaves plugs Gi mixed applied, acid dissolves periphery of glass glass releases ions calcium ions chelate with acid polymer ```

Question 37

What reactions happen 24-72 hours after the glass-ionomer reaction

Answer 37

aluminum replaces calcium, there is an increase in strength, fluoride is released

Question 38

When are fluoride ions released?

Answer 38

released upon setting and then continued over time

Question 39

How does resin modified glass ionomers cure?

Answer 39

visible light and acid-based

Question 40

How does resin modified glass ionomers affect physical property?

Answer 40

increases

Question 41

How does resin modified glass ionomers affect solubility ?

Answer 41

decreases