Dental Materials 1 Final

Front 1

What are typical fillings made of?

Back 1

- Metals & Alloys(Mixture of two or more metals)
- Some porcelain(Ceramic) or resin

Front 2

Bonding of Metals, Ceramics, Polymers & all together?

Back 2

Metal - Metallic bonding
Ceramics - Ionic bonding
Polymers - Covalent & H bonding
Combinations of materials at the atomic, molecular scale are composites

Front 3

Corrosion succeptibility of metals

Back 3

Less noble is more susceptible to corrission

Front 4

Cooling of steel

Back 4

Quenching - More iron carbide forms resulting in harder steel

Tempering - Carbides grow into large perlites which is less tough

Front 5

Cr, C, MO

Back 5

Cr - More than 13% lends corrosion resistance, more than 30% makes it hard to cast & brittle

C - Too much makes it brittle, too little reduces strength b/c of less carbide

MO - Increases corrosion resistance & Str

Front 6

Damascus or Wootz steel

Back 6

Steel formed from high levels of phosphorus & bands of iron carbide form

Front 7

Tempering

Back 7

Increases toughness but reduces strength & hardness

Front 8

Wrought alloys

Back 8

Increased tensile str & hardness but dec in ductility & resistance to corrosion compared to cast structures

Front 9

Stainless Steel

Back 9

Alloys of iron & carbon that contain chromium

Front 10

Chromium resistance to corrosion

Back 10

Forms a strongly adherent coating of chromiumoxide on the surface which prevents further reaction with metal below

Front 11

Smart metals

Back 11

Nitinol, a shape memory alloy that changes crystal structure in response to external stimulus

Will contract 6% in length when heated to 100c

Front 12

General composition of waxes

Back 12

Base wax - Paraffin
Modifier wax
Colorant

Front 13

Inlay was

Back 13

Paraffin, Carnuba, Ceresin, Beeswax, Colorants

Front 14

Ceresin, Carnuba, Beeswax, Rosin

Back 14

-Ceresin & Carnuba increases hardness & water resistance
-Beeswax increases stickiness
-Rosin increases brittleness

Front 15

Carnuba & Melting properties

Back 15

Carnuba increases liquidus line but does not really affect solidus line

Front 16

Chemical forms & Absorption routes for Hg

Back 16

Elemental Hg
-Lungs
Inorganic Hg-S (Cinnabar)
-Lungs
Organic Hg-(CH3)2 (Dimethyl Hg)
-GI

Front 17

Most corrosion prone phase in amalgam deterioration

Back 17

Sn-Hg

Front 18

Dispersalloy

Back 18

2 particle high copper amalgam

Front 19

Precolation

Back 19

Marginal leakage of intraoral fluids

Front 20

OSHA maximum TLV for mercury

Back 20

50 microgram/m^3 for 40 hour work week

Front 21

Gypsum

Back 21

Calcium sulfate, & occurs naturally as dihydrate

Front 22

Extent of leakage through openings Function of?

Back 22

- Opening sizes to the fourth power
- Length of tubule
- Viscocity of fluid
- Diffusion pressure

Front 23

RDT

Back 23

Remaining dentin thickness

<.5mm is high risk

Front 24

Calcium Hydroxinde & ZOE

Back 24

Calcium hydroxide stimulates production of secondary dentin

ZOE eliminates post-operative pain.

Front 25

Cement liners & Bases

Back 25

Used to insure adequate thickness for pulpal protection against heat transmission

Front 26

4 structural components of Composite Resin

Back 26

Acrylic monomer Matrix
Inorganic Fillers
Silane coupling agent
Initiator

Front 27

Dispersed & Continuous phase

Back 27

Filler particles & dispersed & Matrix is continuous phase

Front 28

Filler & Purpose

Back 28

Silica glass

- Makes composite harder, denser & resistant to wear
-Reduces thermal expansion
-Reduces polymerization shrinkage

Front 29

Radiopacity of silica glass

Back 29

Modified with barium, zinc & yittrium to produce radiopacity

Front 30

Composite Matrices

Back 30

Most are Bis-GMA
UDMA in Europe
TEGDMA added to dilute, low viscosity
Bis-EMA reduce volumetric shrinkage & improve handeling

Front 31

Silane coupling agent

Back 31

Used to bond silica glass particles to bis-GMA matrix

Front 32

Initiator & types

Back 32

Used to activate polymerization of the acrylic monomers

Auto-cure chemically
VLC 460-480nm wavelengths

Front 33

4 stages of polymerzation

Back 33

Activation - Production of free radicals with light
Initiation - Free radicals react with other acrylic monomers
Propagation
Termination -

Front 34

Major initiator

Back 34

Camphoroquinone which needs 474nm wavelength.

Front 35

Advantage of VLC

Back 35

Less amine content, so less yellow discoloration and greater color stability

Front 36

Tip of light source & Increments

Back 36

Light should be 2-5 mm away

composite should be placed in increments of 1.5-2mm

Front 37

Fillers & cure time

Back 37

Larger filler particles trasmit light more, and thus cure faster

Front 38

4 of the most used composite resins for teeth based on size, amt & composition of inorganic fillers

Back 38

Microfilled - Highly polishable, but weaker than hybrid. used for class 5
Hybrid - Better physical properties but lacks some luster. Used for class 3&4
Conventional - Replaced by hybrid b/c of rough surface & discoloration
Flowable, packable, sealants

Front 39

Volumetric shrinkage

Back 39

2.6 - 7.1% during setting reaction - Major draw back

Front 40

Four major designs of VLCs

Back 40

QTH - Most common
PAC - Unwanted heat
Argon - May be used in ortho
LED

Front 41

Surface Energy

Back 41

Excess energy of atoms on surface, Liquids have high surface energy

Front 42

Bonding Str

Back 42

Resistance to debonding, measureed in megapascals

Front 43

Sheer Strength

Back 43

Ability to resist forces that cause internal structure of the material to slide against itself

Front 44

Tensile str

Back 44

Ability to resist forces that attempt to pull it apart or stretch it

Front 45

Function of Etchant

Back 45

Phosphoric acid demineralizes & removes 8-10 microns of surface HA. Cleans surface to increase surface energy & dec contact angle

- Makes surface porous, which results in micro mechanical retention

Front 46

Primers

Back 46

Improves wettability of dentin

Front 47

Stronv vs less aggresive acids in etchants

Back 47

Strong acids nonselectively attack smear layer

Less aggressive acids attack organic & inorganic fractions

Front 48

Function of Primers

Back 48

Contains amphipathic molecule that expands collagen matrix that collapsed from etch.

- Copolymerazes with resin resulting in hybrid layer

Front 49

Malleability

Back 49

Measure of capacity of metal to be extended in all directions by a compressive force

Front 50

Fatigue

Back 50

Property of metal to tire & fracture after repeated stressing

Front 51

Strain Hardening

Back 51

Occurs when metal becomes stiffer & harder because of continued or repeated application of a load or force.

Front 52

Tempering

Back 52

Increases toughness but reduces strength & hardness

Front 53

Effects of Cu

Back 53

-Increases corrosion resistance
-Reacts with Sn, to reduce gamma 2 phase
-Increases strength

Front 54

Effects of Sn

Back 54

Most important element of amalgam. Enables amalgam to be handled and controls properties of amalgam

Front 55

Slope of strees strain curve

Back 55

Gives you stiffness of material