Dental Materials Resins

Front 1

What is a composite?

Back 1

A compound of 2 or more different materials with properties that are superior or intermediate to those of the individual constituents.

Front 2

What composes composite?

Back 2

1. Matrix
2. Filler particle
3. Coupling agent
4. Optical-modifier
5. Initiators & accellerators

Front 3

What are the two viscous liquid organic polymer matrix oligomers?

Back 3

1. Bis-GMA (aromatic oligomer)
2. UDMA (urethane diacrylte oligomer)

Front 4

What do the inorganic filler particles of a resin do?

Back 4

1. Improve physical and mechanical properties of the matrix
2. Reduce the polymerization shrinkage
3. Reduce water sorption & coefficient of thermal expansion

Front 5

What is the shape of resin's inorganic filler particles?

Back 5

Spherical or irregularly shaped

Front 6

What are the inorganic filler particles of resins composed of?

Back 6

Quartz, lithium aluminum silicate, zirconia, barium, strontium, zinc, or ytterbium glass

Front 7

Rank the following inorganic filler particles from largest to smallest:
Microfine
Nano
Macro
Micro

Back 7

Macro > Micro > Microfine > Nano

Front 8

Micro-filled composite:
What % filler particle?
How is its polishability?
Which classes is it for?

Back 8

32-50% vol filler particle

Very good polishability

For class III & VI

Front 9

Micro-Hybrid composite:
What % filler particle?
What is it a hybrid of?
Strength-Strong or weak?
Which classes is it for?

Back 9

60-70% vol filler particle

Hybrid of micro & microfine filler particles

High strength

For all classes

Front 10

Nano-filled composite:
What % filler particle?
Polishability?
Strength?
Which classes is it for?

Back 10

78.5% vol filler particle

Very good polishability

High strength

For all classes

Front 11

What is a coupling agent for resins? What does it do?

Back 11

Silanes-A bifunctional molecule

It provides bonding of the inorganic filler particles to the resin matrix

Front 12

What does an optical modifier do? What is it made from?

Back 12

An optical modifier is a pigment that use inorganic oxides to match different shades.

Front 13

What are the 3 steps of addition polymerization?

Back 13

1. Initiation
2. Propagation
3. Termination

Front 14

Composite resins (shink or expand) during polymerization?

What direction is determined by...

Back 14

Shrink

...shrinkage direction determined by cavity shape and bonded surfaces (c-factor)

Front 15

How do you calculate c-factor?

Back 15

Bonded surfaces/Unbonded surfaces

Front 16

Where does resin polymerization cause mechanical stress?

Back 16

1. Enamel/dentin
2. At interface
3. In restoration

Front 17

What are some consequenses of resin polymerization shrinkage?

Back 17

1. Postop sensitivity
2. Microleakage
3. Secondary caries

Front 18

How can resin polymerization shrinkage be reduced?

Back 18

1. More and smaller fillers
2. By using soft-start curing lights
3. Layer composite in 2 mm increments with low c-factor

Front 19

What do bonding agents do?

Back 19

Provide resin composites with attachment to tooth structure/ceramic/metal (Adherend)

Adhesive

Front 20

What is an adherend?

Back 20

The substrate that an adhesive (bonding agent) is bonded to (enamel/dentin)

Front 21

What are 3 different mechanisms that can be used for bonding resin composites?

Back 21

1. Micromechanical
2. Chemical
3. Van der Waals bonds

Front 22

What are 3 factors that affect adhesion to tooth structure?

Back 22

1. Physico-chemical & mechanical properties of the adherend and the adhesive
2. Surface contamination, wettability (contact angle), & adaptation
3. Oral environment

Front 23

What is the % breakdown (by weight) of enamel?

Back 23

95% Inorganic
1% Organic
4% Water

Front 24

What is the % breakdown (by weight) of dentin?

Back 24

70% Inorganic
20% Organic
10% Water

Front 25

Etchants:
pH level?
What type of acid?

Back 25

pH = 1
A thixotrope gel (Phosphoric acid)

Front 26

Primers:
Hydrophilic or hydrophobic?
Monomers or oligomers?
What solvents?

Back 26

Hydrophilic
Monomer
Solvent: acetone, alcohol, water, solvent-free

Front 27

Adhesives:
Hydrophilic or hydrophobic?
Monomers or oligomers?

Back 27

Hydrophobic
Dimethacrylate oligomers

Compatible to monomers in primers and composites

Front 28

What about enamel allows resin better wetting of the surface and penetration into the micro porosities?

Back 28

Its high surface energy.

Front 29

How long should enamel be acid etched for?

Back 29

15-30 seconds...longer for uncut or primary enamel.

Front 30

How long should dentin be acid etched for?

Back 30

15 seconds with 37% phosphoric acid.