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150 Dental Auxilliary Practices > Science Of Dental Materials > Flashcards

Science Of Dental Materials Flashcards

1
Q

Characteristics of the ideal dental material

A 
Biocompatible 
Mechanically stable
Resistant to tarnish
Dimensionally stable
Minimally conductive
Esthetic
Easy to manipulate
Adherent to tissues
Cleanable/repairable 
Cost effective
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2
Q

Classes of materials

A

Metals
Ceramics
Polymers
Composites

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3
Q

Metal dental materials

A

Have high thermal/electrical conductivity

Can bend without breaking - conducive to restore teeth

Opaque

High luster

High melting temperatures

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4
Q

Ceramics (white/tooth colored)

A

Very esthetic results

Former by Union of metal and non-metal

Very brittle, cannot bend

High melting point
Low thermal/electric conductivity

Inert— body may see it as natural bone

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5
Q

Class ceramics/ Polymers

A

Newest

Used for reinforcing agents or fillers for composites

In many dental cements and temporary restorative materials

Used to make dentures, temp crowns, bridges

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6
Q

Bonding

A

A primary bond holds two solids together

Secondary holds liquids together

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7
Q

Atomic arrangements

A

Has an effect on how the materials behave

Rubber can stretch, another may be brittle

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8
Q

Solubility

A

All materials soluble to a point. The least so are ceramics and porcelains

Loss of small organic molecules in the oral cavity

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9
Q

Sorption

A

Uptake of fluids

May cause discoloration of materials

May cause expansion to the material and even enhance the seal at the margin closing area to microorganisms

OR

can cause failure of restorations

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10
Q

Adhesion

A

The force of attraction btw molecules of atoms on two different (dissimilar) surfaces as they are brought in contact

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11
Q

Cohesion

A

Force of attraction btw the molecules or atoms within a given material (not on surface), sticking together

Being mutually attractive

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12
Q

Factors that will determine effectiveness of adhesion/cohesion

A

Wetting

Viscosity

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13
Q

Wetting

A

The extent which the adhesive will spread onto a solid surface

Will help a material spread more easily

Good wetting is needed for materials to stick

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14
Q

Poor wetting is due to…

A

Contamination of material, instruments etc

Plaque
Pellicle

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15
Q

Pellicle

A

Thin layer of organic mix on the tooth deposited from saliva

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16
Q

Surface tension

A

The attraction that the atoms and molecules have for one another

High ST would cause materials to ball up instead of spread out. Ex: Mercury

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17
Q

Hue

A

Refers to the dominant color of the object

18
Q

Value

A

Refers to the lightness of color
Scale 1-10
1= black
10= white

19
Q

Chroma

A

Refers to intensity of the color

Scale 1-10

10= saturated. Is it rich in color or pale?

Natural teeth are around 1-3

20
Q

Translucency

A

Refers to the fact that light enters the tooth

Light can be transmitted, reflected or scattered

21
Q

Tarnish

A

Discoloration

It is reversible

22
Q

Corrosion

A

The deterioration of metal by chemical or electro chemical reaction

Causes the restoration to break down or fail

Not reversible

23
Q

Crevice corrosion

A

A gap, groove or slot exists next to or on a metal

Example: Margin around an amalgam

Is an issue because of secondary decay/recurring decay forming around the margin

24
Q

Types of forces seen in oral cavity

A

Tensile
Compressive
Shear

25
Q

Tensile force

A

Force that pulls objects apart

26
Q

Compressive force

A

An object subject to force, application of force on an object, squeezing together

27
Q

Shear force

A

Sliding the top of an object over another

28
Q

Stress

A

Force per area, when the stress exceeds the cohesive strength of the object, the object breaks

29
Q

Strain

A

One force is applied and the object experiences some deformation (change)

30
Q

Elastic modulus

A

The stiffness of a material

31
Q

Elastic limit

A

Maximum stress limit

32
Q

Brittle

A

Low ductility

33
Q

Maximum flexibility

A

Measure of elastic limit

34
Q

Deformation

A

Permanent strain

35
Q

Ultimate strength

A

Maximum stress that can be withstood before breaking

36
Q

Percent elongation or ductility

A

Measure of dimensional change that a wire can undergo before breaking

37
Q

Hardness

A

Refers to the ability of a material to resist forces indentation

38
Q

Fatigue

A

A repeated application of stress to an object. May cause tiny cracks and cause failure

39
Q

Creep

A

Gradual of a permanent change that occurs because of a constant load

40
Q

Fracture toughness

A

Ability to resist further movement of an existing crack

41
Q

Wear

A

To surface is brought in direct contact or indirect contact and/or with a third body acting between them

Two bodies - sandpaper and a surface

Three bodywear - toothbrush, toothpaste and a tooth

150 Dental Auxilliary Practices (16 decks)

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