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Dental Materials > Composite resins and glass-ionomers > Flashcards

Composite resins and glass-ionomers Flashcards

1
Q

What are the benefits of composite amalgam

A

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

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2
Q

What are the two main components of composite?

A

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

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3
Q

Are organic polymers or inorganic materials stronger?

A 
inorganic = stronger and good processing
organic = tough (resistant to wear)
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4
Q

what are two ways to change cross-link density?

A

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

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5
Q

What are the three types of curing?

A

mixing (chemical), heat, light

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6
Q

What is characteristic of mixing curing?

A

operator dependent working time, no special tools, chairside

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7
Q

What is characteristic of heat curing?

A

consistent, high degree of cure, not good in vivo

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8
Q

What is characteristic of light curing?

A

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

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9
Q

What are the components of a composite resin SYSTEM?

A

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

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10
Q

What is the most common resin system?

A

BisGMA-TEGDMA

plus a structural component and diluent

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11
Q

What are the chains of the methylmethacrylate?

A

four distinct chains

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12
Q

What are the characteristics of polymer bonds?

A

covalent bonds, high MW, long and nonmetallic elements

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13
Q

How do polymers derive their strength and properties?

A

entanglement, like cooked spaghetti

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14
Q

What food is consistent with the viscosity of resin?

A

honey

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15
Q

Why is BisGMA used if its is so viscous?

A

it provides physical properties of composite filling

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16
Q

What is often used to make the BidGMA less thick?

A

TEGDMA at 30-50 wt %

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17
Q

What are the two usual fillers?

A

silica or zinc based inorganics

18
Q

What wt percent is fillers of the composite filling?

A

50-80 wt %

19
Q

What organic group is on the surface of fillers?

A

-OH

20
Q

What are the three grades of fillers?

A

micron = fine
nano = microfine
nano in polymer matrix

21
Q

Why would a smaller filler size be used?

A

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

22
Q

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

A

77-88%

23
Q

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

A

MAX of 38 wt %

24
Q

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

A

50-60 wt %

25
Q

What is characteristic of hybrid composites?

A

mixture of filler sizes with a loading of 70 wt %

26
Q

What is characteristic of flowable composite?

A

thin, lower filler, low modulus, higher shrinkage

27
Q

How is polymer shrinkage measured?

A

density changes

28
Q

Why is polymerization shrinkage important?

A

direct composite restoratives and materials that require dimensional stability

29
Q

What are some effects of polymer shrinkage?

A

Stress on tooth structure, microleaks, secondary carries

30
Q

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

A

lower

31
Q

Why do composites fail?

A

fracture or secondary caries

32
Q

What is characteristic of glass-ionomer cement?

A

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

33
Q

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

A

Acid polymer in aqueous solution

basic glass

34
Q

What are the specific components of glass-ionomer cement?

A

polyacid
basic glass
water
modifiers (+) tartaric acid

35
Q

What is characteristic of basic glass?

A

aluminafluorosilicate glass

the components are melted, cooled, and ground

36
Q

Describe the setting reaction of glass-ionomer

A 
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
37
Q

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

A

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

38
Q

When are fluoride ions released?

A

released upon setting and then continued over time

39
Q

How does resin modified glass ionomers cure?

A

visible light and acid-based

40
Q

How does resin modified glass ionomers affect physical property?

A

increases

41
Q

How does resin modified glass ionomers affect solubility ?

A

decreases

Dental Materials (6 decks)

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