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operative > intro to biomaterials-amalgam > Flashcards

intro to biomaterials-amalgam Flashcards

1
Q

mixture and alloys(mix with metal):

A

porcelains and ceramics
polymers

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2
Q

two types of polymers:

A

elastomeric (impression material)
plastics (denture base, sealants)

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3
Q

composites are:

A

polymers with fillers

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4
Q

performance of all dental materials depends on their

A

atomic structure

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5
Q

atomic structure determines ____ and ____ properties of materials

A

mechanical and physical

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6
Q

2 types of interatomic bonds:

A

primary and secondary

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7
Q

ionic, covalent, metallic

A

primary

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8
Q

hydrogen bond, van der waals forces

A

secondary

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9
Q

primary bonds: ionic
electrostatic attraction of _____ and ______ charges

A

positive and negative

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10
Q

involves electron transer between ions

A

primary bonds: ions
(one becomes + and one becomes -)

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11
Q

examples of primary bonds:ionic

A

ceramics and gypsum

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12
Q

properies are non-directional , strong bonds
and no free electrons with GOOD THERMAL and electrical insulators

A

primary bonds: ionic

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13
Q

2 atoms share electron

A

covalent

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14
Q

properties:
directional bonds
low electrical and thermal conductivity
water INSOLUBLE

A

primary bonds: covalent

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15
Q

examples are water, glass, polymers, composite

A

primary covalent bond

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16
Q

cluster of positive metal ions surrounded by a gas of electrons
non-directional bonds, high electrical and thermal

A

primary bonds: metallic

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17
Q

examples of metallic primary bond

A

amalgam and gold alloy

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18
Q

4 classifications of material properities

A

biological
surface
physical
mechanical

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19
Q

biological response to material when in contact with human body
(ex. gingivitis from plaque)

A

biological

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20
Q

unique properties of material associated with its surface
(dental retention and adhesive bonding)

A

surface

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21
Q

depend on TYPE OF ATOMS and the bonding present in material; size or shape have NO AFFECT
(optic color or gloss, thermal conductive)

A

physical

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22
Q

with physical classification, what is it dependent on and what has no affect

A

dependent on type of atoms
size and shape no affect

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23
Q

reaction of a material to the application of external force, size and shape of specimen affect properties
(structure sens and applied force is load)

A

mechanical

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24
Q

what affects properties in mechanical classification?

A

size and shape and rxn of external force (load)

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25
Q

structure insensitive :
sensitive:

A

insensitive physical
sens mechanical

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26
Q

when does stress develop

A

when load (force) applied to material, stress develops

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27
Q

stress =

A

load per unit area

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28
Q

how much stress a material can withstand before it breaks

A

fracture strength

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29
Q

type of strength measured is dependent on

A

type of force applied

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30
Q

pushing-
pulling-
sliding-
twisting-
bending-

A

pushing- compressive
pulling- tensile
sliding- shear
twisting- torsion
bending- flexure

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31
Q

highest strength measure for most materials

A

compressive strength

32
Q

compressive strength measure of the stress necessary to

A

fracture material by 2 opposing forced directed toward each other

33
Q

lowest strength for most materials

A

pulling/tensile strength

34
Q

measure of stress necessary to fracture material by 2 opposing forces directed away from each other

A

tensile/pulling force

35
Q

usually requires high loads to cause failure:
failure occurs at lower loads:

A

usually requires high loads to cause failure: compressive
failure occurs at lower loads: tensile

36
Q

intermediate strength between compressive and tensile

A

shear strength/sliding

37
Q

clinical situation with shear force:

A

implant-bone interface

38
Q

not relevant to direct or indirect dental restorations
used to place dental implants
fatigue of endodontic rotary files

A

torsion strength

39
Q

what force is measured using a 3 point bend test

A

flexural strength

40
Q

compressive load and combination of compressive and tensile stress

A

3 point bend test

41
Q

what is vital due to occlusal load on direct restorations such as amalgam and composite? indirect (everything getting chewed on)?

A

flexural strength (3 point bend test)

42
Q

examples of dental stress:

A

protrusive movements (ant teeth or flexure load on incisors)
and
posterior occlusion (chewing=compressive load)
at marginal ridge contact areas and at fossa areas

43
Q

occlusal stress =

A

load(force)/occlusal contact

44
Q

allows distrubution of occlusal load acorss max area = minimum stress known as

A

tripodized occlusal contacts

45
Q

this results in decreased AREA

patient’s occlusal force stays the same but occlusal stress is increased!

A

premature contact

46
Q

deformation that occurs in a material when force is applied to the material

A

strains

47
Q

strain=

A

change in length (deformation)/unit original length

48
Q

stress and what are related
if you have one you will have other

A

stress and strain

49
Q

temporary distortion of material by applied force

STRAIN IS BELOW ELASTIC LIMIT

when force removed, materials revert back to original form

A

elastic strain

50
Q

permanent distortion of material

STRAIN IS BEYOND ELASTIC LIMIT

when force removed, shape remains changed

A

plastic strain

51
Q

effective barrier against recurrent caries

A

amalgam

52
Q

amalgam alloy composition:
1
2
3
4

A
  1. Ag 70%
  2. Sn 16% expansion
  3. Cu 13% strength
  4. 1% deoxidizer
53
Q

high copper amalgam is superior to conventional amalgam. presence of copper nearly eliminates ______ resulting in stronger restoration

A

gamm-2-phase

54
Q

what amalgam shapes:
1. lathe type particles mixed with small spheres
-requires more condensation force
-most commonly used type of amalgam
-low early strength

  1. outdated and particles formed by cutting blocks- large irregular
  2. higher early strength and 24 hour strength
    -requires less condensation force
A
  1. admixed
  2. lathe
  3. sperhical
55
Q

less what in final restoration of amalgam is superior

A

less mercury

56
Q

most critical variable with almagam manipulation?
most common error made by dentists

A

condensation

57
Q

what are the 4 variables of amalgam manipulation

A

mercury to alloy ratio
trituration
condensation
carving and finishing

58
Q

amalgam:
high ____ strength

low ____strength

A

high compressive strength
low tensile strength

59
Q

amalgam brittle in small bulk
_____mm pulpal depth
_____isthmus

A

pulpal depth: 1.5-2mm
isthmus: 1 mini

60
Q

what element is added to prevent amalgam expansion

A

zinc

61
Q

the order of needed compression force for amalgams from high to low is:

A

lathe>admixed>spherical

62
Q

what will increase the strength of amalgam

A

high copper content

63
Q

does premature occlusal contact increase or decrease stress on the tooth? why?

A

increase
because the surface area contact is smaller (decreased area)

64
Q

energy absorbed during elastic strain:
energy absorbed during plastic strain:

A

elastic: resilence, temporary
plastic, permanent distortion

65
Q

T/F.
elastic limit delineates the transition from elastic strain to plastic strain.

T/F: brittleness a property caused by lack of elastic deformation

A

first T
second F

66
Q

which of the following describes amalgam restorations compared to composite restorations?
a. less recurrent decay
b. moisture sens
c. lasts for a longer time
d. a and c

A

less recurrent decay
lasts for a longest time

67
Q

amalgam is sensitive to moisture contamination during

A

placement but still better choice if moisture control is difficult

68
Q

___ are formed which expands and fill tiny voids, preventing microleakage. no other dental restorative material does this

(in amalgam)

A

oxides

69
Q

liner is placed in ____ layer over dentin
base is placed in _____layer on floor of prepared cavity

A

liner thin layer over dentin

base thick layer on floor of prepared cavity

70
Q

stimulates reparative dentin formation:

A

calcium hydroxide LINER

71
Q

light cure and releases fluoride over time

A

glass ionomer
LINER/BASE

72
Q

what is true about both liners and bases?
a. stimulate reparative dentin
b. can only be placed in center of prep
c. release fluoride
d. used in preps of any depth

A

a. wrong- only liner
b. true- keep away from margins
c. wrong- only base
d. wrong- deeper areas only

73
Q

what are 4 causes of bulk fracture in an amalgam restoration?

A
  1. premature occlusal contact
  2. improper condensation
  3. fatigue of the material
  4. improper trituration
74
Q

true or false

tarnishing and corrosion of amalgam changes the amount of material in a preparation

A

true

75
Q
  1. copal resin
  2. bonding agents
  3. gluteraldehyde (gluma)
A

types of desensitizers

76
Q

surface of dentin when it is cut

A

smear layer

77
Q

the cutting edge of a cutting instrument is similar to the face of a non-cutting instrument just as the blade of a cutting instrument is similar to the ____ of a non-cutting instrument

A

nib

operative (6 decks)

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