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NBDHE > Dental Biomaterials > Flashcards

Dental Biomaterials Flashcards

(80 cards)

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1
Q

Tensile force

A

pulls objects apart

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2
Q

Shear force

A

pushes one part on an object in one directions and another part in the opposite direction with a twisting or rotating motion

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3
Q

Stress

A

internal force that resists the applied force, and can resist the external force up to the point of fracture.

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4
Q

ultimate strength

A

highest stress that can be borne by the object before it fractures or breaks

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5
Q

fracture strength

A

point where an object breaks

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6
Q

ductility

A

ability to withstand deformation under stress before fracturing or breaking

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7
Q

brittleness

A

ability to fracture or break before deformation occurs

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8
Q

malleability

A

ability to be compressed without fracturing

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9
Q

strain

A

deformation of material in response to stress, the change in shape and size

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10
Q

Elastic deformation

A

the object recovers after stress is released

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11
Q

proportional limit

A

point of the stress/strain diagram at which stress and strain are directly proportionate to one another. At this point, if stress is removed there is no deformation

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12
Q

yield point

A

the point just before the material is permanently deformed

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13
Q

galvanism

A

a direct current of electricity especially when produced by chemical action
EX: fork touching a metal restoration causing a shock feeling

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14
Q

thermal conductivity

A

ability of heat to spread

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15
Q

coefficient of thermal expansion

A

change in volume and length of an object in response to a change in temperature

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16
Q

The higher the coefficient of expansion, the ______ the degree of contraction and expansion

A

greater

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17
Q

microleakage

A

leakage of fluid and bacteria that occurs at the interface of the tooth and the restoration margins due to the difference in the coefficient between the tooth and the material.

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18
Q

percolation

A

movement of fluid in the microscopic gap of the restoration margin as a result of differences in expansion and contraction of the tooth and the restoration with temperature change.

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19
Q

retention

A

ability for a material to maintain position without being displaced under stress

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20
Q

mechanical bonding

A

material penetrates into irregularities (pores on tooth structure) and interlocks mechanically.

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21
Q

wetting

A

degree to which the liquid adhesive spreads over the surface
the better the spread, the more retention.

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22
Q

cohesion

A

force of attraction between LIKE kinds of atoms and molecules within a material, resulting in a tenacious bond.

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23
Q

Adhesion

A

force of attraction between UNLIKE atoms and molecules on two different surfaces when brough into contact with each other

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24
Q

hue

A

color

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25
chroma
intensity of color
26
value
lightness or darkness of color
27
opacity
light is absorbed by object
28
modulus of elasticity
measures the stiffness of an elastic material.
29
elastic limit
maximum stress that a material can withstand without being permanently deformed
30
hardness
measure of resistance to indentation when a compressive force is applied
31
Moh's hardness scale
compares minerals and their ability to scratch another mineral
32
Knoop hardness
examines the indentation caused by a diamond point under a microscope
33
reversible hydrocolloid: agar agar
material is heated, converted into sol, and cooled to become a gel. Can be reused multiple times and provides better details than alginate.
34
Irreversible hydrocolloid: aliginate
less accurate impression material than agar/rubber
35
polysulfide, silicone, polyether, and vinyl materials
hydrophobic more rigid and provides better details than alginate used for inlay, onlay, crown, bridge, and secondary (final) impressions
36
syneresis
loss of water mostly by evaporation
37
imbibition
ability to absorb water
38
gypsum in dentistry
calcium sulfate hemihydrate, obtained by a water evaporation process called calcination most common material used for replication in dentistry.
39
Plaster
type 2 irregular porous particles. High setting expansion and low compressive strength. requires more water
40
Stone
type 3 less irregular particles low setting expansion and higher compressive strength. Used for study models
41
Diestone
type 4 and 5 non porous, smoothest, and dense particles. Highest compressive strength. Used for crowns and bridges.
42
What kind of reaction occurs with a hemihydrate and water
exothermic
43
T or F: all gypsum expands upon setting
true
44
wet strength
strength when excess water is present
45
dry strength
strength when excess water is removed.
46
Can a clinician accelerate the setting time of gypsum products by adding borax to it?
no, borax is considered a retardant. Potassium sulfate acts as an accelerator
47
direct restoration
material is placed directly onto a prepared tooth done in one appointment
48
indirect restoration
restoration is placed after it is fabricated in the lab takes more than one appointment.
49
inlay
lies withing the cusp of a tooth
50
onlay
covers one or more cusp tips
51
Characteristics of gold
resists tarnishing resists corrosion highly resistant to fractures and is durable may cause galvanic shock thermal expansion is CLOSEST to the natural tooth surface.
52
Characteristics of porcelain
strong and durable produces dentures, PFM crowns, bridges, veneers, onlays, and inlays provides excellent match to natural teeth color, intensity, and translucency. Do not use acidulated fluoride
53
Characteristics of composite
major component is dimethylacrylate (bis-GMA) needs polymerization can be light-cured or self cured. poor conductor of heat and electricity good flow resistant do not use acidulated fluoride
54
Components of amalgam
40-60% silver 27-30% tin 13-30% copper 1% zinc set with mercury.
55
Silver
enables setting expansion and causes an increase in strength and resistance to corrosion
56
copper
increases strength. Minimized corrosion, tarnish, creep, and sensitivity.
57
Tin
mat cause setting contraction whereas copper improves strength, minimized corrosion, and tarnish, brings down creep, and brings down cases of marginal leakage.
58
Zinc
brings down the oxidation of other alloys in the metal. It has been proved that zinc-containing amalgams have a longer life when compared to non-zinc amalgams.
59
indium
strong, especially during compression similar compressive strength to enamel. inexpensive
60
undesirable traits of amalgam
lower tensile and shear strength corrodes creeps galvanism overhangs
61
low-copper amalgam
lower strength
62
high copper amalgams
higher strength, corrosion-resistant
63
lathe-cut amalgams
powder composed of small shavings
64
spherical amalgams
particles in the form of small spheres
65
Admixed alloy amalgams
mixture of lathe-cut and spherical alloys, produces better contacts
66
Ceramic
also called dicor more durable for inlays compared to composite
67
What is the purpose of cements/liners/bases/varnishes
to protect the tooth and provide better retention
68
Cements
retain restorations in the mouth and provide thermal insulation near the pulp.
69
Bases
insulate and protect the tooth substitute dentin removed provide thermal and chemical protection and can resist condensation forces
70
liners
seal dentinal tubules and protect against leakage of irritants present in the saliva and restorative materials CANNOT resist compressive forces.
71
Zinc oxide-eugenol (ZOE)
combo of zinc oxide powder and eugenol liquid
72
Zinc oxide-eugenol use
used as a liner for its sedative effect to the pulp called obtundent Used for temporary fillings can be used as impression material for complete dentures
73
Zinc phosphate
zinc oxide powder and phosphoric acid liquid combined causing an exothermic reaction.
74
polycarboxylate (durelon)
mainly used for permanent cementation of ortho bands and brackets. does not release heat
75
Glass ionomer (KETAC-CEM)
binds to dentin and releases fluoride Commonly used in Class 5 restorations
76
Resin
Mostly made up of bisphenol A- glycidyl methacrylate (BIS-GMA) commonly used as a cement to retain restorations
77
Calcium hydroxide
used as a liner or base, or root canal filling material stimulates the production of reparative dentin
78
Varnish
cavity liner applied under gold/amalgam restorations. Numbs pain, blocks penetration of chemicals, and seals dental tubules to prevent transfer of heat/cold
79
Conditioning/ etching
removes the smear layer and creates more pores for mechanical bonding 37% phosphoric acid
80
Finishing
removes excess materials and produces smooth surfaces

NBDHE (13 decks)

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