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Operative Dentistry > Materials used in restorative dentistry > Flashcards

Materials used in restorative dentistry Flashcards

1
Q

Advantages of amalgam

A
  • lower cost compared to composite
  • durable and strong
  • high wear resistance
  • ease of placement
  • less technique sensitive
  • self-sealing (due to expansion)
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2
Q

Disadvanatages of amalgam

A
  • poor esthetics
  • conductive (temperature and galvanic reaction)
  • less conservative preps needed
  • preparations are more difficult
  • “mercury exposure” complaints
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3
Q

Amalgam indications

A
  • posterior restorations
  • selected anterior restorations
  • heavy occlusal loads
  • high caries risk patients
  • working field compromised
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4
Q

contraindications of amalgam. Why?

A

patients with renal disease/immunocompromised.

some studies have shown that these patients are unable to remove amalgam from their system

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5
Q

bonded amalgam was developed to increase ___ form

A

resistance

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6
Q

How is bonded amalgam different from conventional amalgam?

A
  • adhesive is added prior to addition of amalgam
  • dual cured - it can be light cured or cures over time
  • Observed less microleakage and staining
  • increased strength of coronal structure
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7
Q

Amalgam reaction

A

Hg + Ag3Sn –> Ag3Sn + Ag2Hg3 + Sn7Hg8

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8
Q

What is the weakest phase of the amalgam reaction and how can this be reduced?

A

Weakest phase is gamma-2 (Sn7Hg8). It is more corrosion prone. This can be reduced with the addition of Copper

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9
Q

Overall reaction for high copper amalgam

A

Hg + Ag3Sn +AgCu –> Ag3Sn + Ag2Hg3 + Cu6Sn5

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10
Q

Contamination with moisture in an amalgam restoration leads to what disadvantages?

A
  • decreased strength
  • increased corrosion
  • increased creep
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11
Q

What is creep?

A

deformation under occlusal load. Ideally, you want less creep

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12
Q

How much copper required to be considered high copper amalgam?

A

> 12% Cu

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13
Q

Why is zinc added to Ag?

A

To enhance mechanical properties, reduce marginal fracture, and increase longevity

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14
Q

How much condensation and carving time in extended carving Ag?

A

5 min cond. time. 7 min carving time

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15
Q

BisGMA stands for

A

bis-glycidyl methacrylate

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16
Q

4 major components of composite resins

A
  • Organic polymer matrix (resin -BisGMA)
  • inorganic filler particles
  • silane coupling agent
  • initiators
17
Q

Curing occurs through a ____ reaction

A

polymerization

18
Q

3 uses of composite resins

A
  • replacement of carious or fractured tooth structure
    2. restoring erosion and abrasive defects in cervical areas
    3. esthetically re-creating teeth with developmental anomalies
19
Q

To place composite, the entire cavosurface margin must be on ____

A

enamel. Bonding to dentin is unreliable

20
Q

What effect does hgher filler loading have on the composite material?

A
  • increases ease of handling material (less sticky and more packable)
  • increases the strength of the material (fracture resistance)
  • decreases polymerization shrinkage
  • increases color stability
21
Q

filler loading for:

  • Macrofills
  • Microfills
  • Hybrids
  • Nanofills
  • Flowable
A
  • Macrofills - high
  • Microfills - low
  • Hybrids - high
  • Nanofills - high
  • Flowable - low
22
Q

Advantages of composite resins

A
  • aesthetic
  • bonded total seal with enamel
  • conservation of tooth
  • manipulative control with LC material
  • Non conductive
  • tooth reinforcement
  • no metal/Hg
23
Q

Disadvaantages of composite resins

A
  • technique sensitive
  • difficult to recreate interproximal contact
  • poor wear in areas of high masticatory forces
  • staining
  • polymerization shrinkage
  • higher rates post-op sensitivity
  • recurrent decay
  • people say it contains BPA”
24
Q

Cimposite resins indications

A
  • anterior restos
  • selected posterior restos where masticatory forces are limited
  • preparation cavosurface margins are all on enamel and do not end on occlusal static contact
25
Q

contraindications of composite

A
  • patients with high caries risk
  • large posterior restos with heavy occlusal contacts
  • moisture control is compromised
  • deep gingival boxes with no enamel on gingival margin
26
Q

How is retention achieved in composite vs amalgam?

A
  • In composite resins, retention is achieved through bonding to tooth structure
  • convergence is required for mechanical retention in Ag
27
Q

Line angles in composite vs amalgam preps

A
  • composite: rounded internal line angles

- Ag: near 90 degree line angles

28
Q

composition of glass ionomer

A
  • silicate glass powder (calciumaluminofluorosilicate glass)

- polyacrylic acid

29
Q

Biggest difference between GI and composite?

A

more bonding in GI to dentin

30
Q

Setting of GI involves a(n) ____ ___ reaction

A

acid-base reaction.
Ca2+ and Al3+ ions released from glass particles allow for adhesion to the tooth structure. Sustained release of F- ions from the glass matrix

31
Q

Advantages of GI

A
  • chemically bonds to dentin, cementum, and enamel
  • anti-cariogenic due to F- release
  • non-irritating to the pulp
32
Q

Disadvanatges of GI

A
  • esthetics (opaque)
  • initial bond strength is low
  • initially sensitive to hydration and dehydration
33
Q

indications for GI

A
  • cervical abrasion, erotion, abfraction lesions
  • High CR
  • margins on cementum
34
Q

contraindications of GI

A
  • esthetic considerations

- areas of high masticatory forces

Operative Dentistry (11 decks)

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