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Operative > Composite Resin > Flashcards

Composite Resin Flashcards

1
Q

Enamel bonding is _______ and _______.
Dentin bonding is _______ and _______.

A

Enamel = reliable & predictable
Dentin = not as reliable & predictable

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2
Q

Describe enamel bonding.

A
  • Acid etching transforms the smooth low energy enamel surface into an irregular surface, with increased surface free energy and wettablity
  • The increased wettability allows fluid-based resin to easily spread into the irregularities and become mechanically interlocked following polymerization
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3
Q

Enamel bonding can generate up to _____ MPa of shear bond strength, when conducted without moisture contamination.

A

20 MPa

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4
Q

Describe dentin bonding compared to enamel bonding.

A

equally as strong as enamel bonding but not as reliable and predictable

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5
Q

composition of dentin vs enamel that results in less reliable and predictable bonding

A

Dentin has a HIGHER WATER COMPOSITION than enamel, which reduces the effectiveness of acid etching.

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6
Q

structure arrangement of dentin vs enamel that results in less reliable and predictable bonding

A

Enamel rods are arranged in parallel and have a regular pattern that is easily etched.
Dentin tubules are composed of a disorganized organic matrix of collagen.

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7
Q

tubule arrangement of dentin that results in less reliable and predictable bonding

A

dentinal tubules become larger in diameter and more numerous near the pulp, this results in decreased bond strength closer to the pulp due to the interference of dentinal fluid

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8
Q

smear layer of dentin that results in less reliable and predictable bonding

A

the smear layer will plug the dentinal tubule orifices to form a smear plug

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9
Q

smear layer of dentin that results in less reliable and predictable bonding

A

the smear layer will plug the dentinal tubule orifices to form a smear plug, which will decrease dentinal permeability by up to 90%, the smear layer is composed of the shavings of hydroxyapatite and collagen generated during tooth preparation

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10
Q

content of acid etch

A

30-40% phosphoric acid (commonly 37%)

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11
Q

how to acid etch

A

apply for 15 seconds, rinse with water for 10 seconds

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12
Q

What does acid etch do?

A
  • dissolves the smear layer and cleans the surface debris
  • exposes the collagen layer in dentin, widening the dentinal tubules
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13
Q

When is GLUMA applied?

A

After etching, the surface must be gently air-dried and left moist. GLUMA can be applied to re-wet the tooth.

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14
Q

appearance of enamel after etching, and why

A

chalky white appearance due to the creation of microporosity

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15
Q

content of primer

A

HEMA, an amphiphilic resin monomer wetting agent and solvent (common solvents are acetone, ethanol, and water)

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16
Q

purpose of primer

A

infiltrate the enamel prisms and dentinal tubules to prevent collagen collapse and allow for better adhesion

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17
Q

After application, this step must be gently air-dried to evaporate the solvent and leaving only the monomers.

A

primer

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18
Q

________ can result in an allergic reaction called contact dermatitis when it contacts bare skin.

A

Primer

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19
Q

allergic reaction that primer can cause when it contacts bare skin

A

contact dermatitis

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20
Q

content of bond/adhesive

A

bis-GMA monomers

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21
Q

Bond/adhesive chemically bonds to the primer below and composite resin above through _________ bonds.

A

methylmethacrylate (MMA) bonds

22
Q

After application, this step is gently air dried to evaporate the solvent and light cured.

A

bond or adhesive

23
Q

layer of micro-mechanical retention between the resin and irregular tooth surface

A

hybrid layer

24
Q

the resin that is polymerized after penetration into the exposed dentinal tubules

A

resin tags

25
Q

main contributors to composite resin retention

A

micro-mechanical bond created by the hybrid layer followed by the chemical bond between the primer, adhesive, and composite

26
Q

4th generation etch and rinse systems

A

3-step process with each etch, primer, and adhesive as individual steps

27
Q

5th generation etch and rinse systems

A

2-step process in which etch is followed by a primer and adhesive product combined into a single step

28
Q

technique in which etchant is applied selectively to enamel to potentially reduce post-operative sensitivity while maintaining a strong enamel bond

A

selective etch technique

29
Q

Properties of a self-etch system and its implications:

A

Combines the acid etch with another step, the acid etchant is less potent because it is not rinsed after application

Implications:
- smear layer is not removed, a carbide bur is recommended for preparation to minimize smear layer formation
- less post-op sensitivity
- weaker enamel bond

30
Q

6th generation etch and rinse systems

A

2 step process which combines acid etch and primer into a single step followed by adhesive

31
Q

7th generation etch and rinse systems

A

combines acid etch, primer, and adhesive into a single step

32
Q

defined as a material that is composed of two or more constituent parts

A

composite

33
Q

Composition of composite (3):

A

Resin matrix- organic, highly viscous pre-polymer, proceeds to polymerize into a solid form when cured (bis-GMA)

Filler particles- small RO particles of silica and powdered ceramic glass which ranges in different shapes and sizes

Coupling agent- coats filler particles to promote adhesion between the fillers and resin-matrix (silane)

34
Q

Leaching of _________ can happen with uncured resin and through the wearing of composite.

A

bisphenol-A (BPA)

35
Q

Composite resins can be categorized by filler characteristics.

Larger fillers =
Higher filler content =

A

Larger fillers = more strength, low polishability and high wear into a rougher surface

Higher filler loading = lower matrix content which results in less water absorption

36
Q

Name the composite resin type:
- conventional composites that are no longer used
- 80% filler
- 8um particle size
- high strength, low polishability, fast wearing of resin matrix to increase roughness overtime

A

macrofill

37
Q

Name the composite resin type:
- 40% filler
- 0.04um particle size
- weak, better polish/ear resistance due to higher matrix composition, can flex under pressure

A

microfill

38
Q

Name the composite resin type:
- 80% filler
- 1um particle size

A

hybrid

39
Q

Name the composite resin type:
- 0.005-0.01um particle size
- small particles can group together with each other to form larger particles, resulting in a full range of filler sizes

A

nanofill

40
Q

Name the composite resin type:
- incorporates nano-sized and larger particles

A

nanohybrid

41
Q

Composite resins can be categorized based on their viscosity (2):

A

Flowable composite- various composites with minimum filler amount, lower wear resistance

Packable composite- composites with high filler amount, very viscous, handles like amalgam

42
Q

Composites can be categorized based on their method of polymerization (3):

A

Self-cure or chemical cure
Light cure
Dual cure

43
Q

a two-paste system which must be mixed in equal parts to initiate the polymerization reaction, have a limited working time of around 2 minutes

A

self-cure or chemical cure composites

44
Q

Two-paste system of self-cure composites:

A

Base paste- composed of composite and tertiary amine (activator)

Catalyst paste- composite and benzoyl peroxide (initiator)

45
Q

a single paste system which does not involve mixing and requires a 468 nm blue visible light to initiate the polymerization reaction

A

light cure composite

46
Q

light required to cure composite and the photoinitiator

A

468nm blue light / camphorquinone

47
Q

composite resin combining elements of self-cure and light cure, useful for large build-ups which allow a light curing of the surface and a chemical reaction to cure the deeper material

A

dual cure composite

48
Q

initiator for self-cure vs light cure vs dual cure composite

A

Self-cure = benzoyl peroxide
Light cure = camphorquinone
Dual cure = both

49
Q

How does polymerization shrinkage occur?

A

During the polymerization reaction, free radicals break the carbon double bond in a bis-GMA monomer to form a single bond with an adjacent monomer. The side group will cross-link by sharing electrons via a covalent bond to create strong cured material. The continuous recruitment of monomers results in a decrease in resin volume and subsequent shrinkage.

50
Q

common range of polymerization shrinkage of composite resins

A

2-3%

51
Q

used to represent the expected polymerization shrinkage, determined by the proportion of bound to unbound surfaces of the composite resin restoration

A

configuration (C) factor

52
Q

high vs low C factor

A

Higher C-factor = high chance for shrinkage, micro-leakage, and post-op sensitivity

To minimize shrinkage, smaller increments of 2mm can be cured for a larger restoration.

Operative (7 decks)

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