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Exam 2: DFRD 5001 > Dental Cements > Flashcards

Dental Cements Flashcards

1
Q

Substance that hardens to a solid state to join two surfaces to bind devices and prostheses to tooth structures or to each other.

A

Cement

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2
Q

A viscous cement-like material that fills a gap between bonded materials.

A

Luting agent/Luting cement

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3
Q

The thickness of a continuous cement after setting under pressure. It is an indication of the viscosity of the cement during seating. Lower implies lower viscosity. For luting applications, the maximum allowable is 25 μm; low is preferred, so that excess cement can be expressed more easily.

A

Film thickness

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4
Q

The thickness of the cement between the tooth structure and a cemented cast crown, inlay, onlay, or veneer. An acceptable range in the literature is from 25 to 120 μm. However, if it is associated with resin cements can exceed 150 μm.

A

Cement thickness

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5
Q

Luting (cementing) agents in the placement of indirect restorations and orthodontic brackets and bands

A

Main uses of dental cements

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6
Q
  • Bases under direct restorations
  • Temporary fillings
  • Pulp capping agents
  • Root canal fillings
  • Restoratives for class V erosion lesions
  • Pit and fissure sealants
A

Additional uses of dental cements

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7
Q

Composition of resin cements

A

Similar to composite filling materials, but with lower filler loading and viscosity

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8
Q

Curing mechanism of resin cements

A

Self or chemically cured – come in two components that are mixed to begin the polymerization

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9
Q

Advantages of resin cements

A
  • Strong
  • Not very soluble
  • Adhesive
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10
Q

Disadvantages of resin cements

A
  • Unacceptably high film thickness

* Marginal excess difficult to remove

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11
Q

Composition of powder-liquid cements

A
  • Powder is a Lewis base

* Liquid is a Lewis acid

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12
Q

Reaction scheme of power-liquid cements

A

Forms a salt, salt solidifies and becomes a matrix

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13
Q

Two classes of powder of powder-liquid cements

A
  • Zinc oxide based

* Alumino-silicate glass (AS glass) based

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14
Q

Three classes of liquids of powder-liquid cements

A
  • H3PO4 (phosphoric acid) based
  • Eugenol and analog based
  • Polyacid (polycarboxylic acid) based
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15
Q

Composition of zinc phosphate cement

A

ZnO + H3PO4

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16
Q

Optimal powder liquid ratio of zinc phosphate cement

A

2.6:1

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17
Q

Advantages of zinc phosphate cement

A
  • Longest history of success
  • High strength
  • Acceptable film thickness
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18
Q

Disadvantages of zinc phosphate cement

A
  • Low initial pH
  • No adhesion to tooth structure
  • No anticariogenic properties
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19
Q

Manipulation of zinc phosphate cement

A
  • When mixed, phosphoric acid dissolves the zinc oxide, which reacts with the aluminum phosphate and forms zinc aluminophosphate gel on the remaining undissolved zinc oxide particles. The set cement contains unreacted zinc oxide particles encased in an amorphous matrix of zinc aluminophosphate.
  • The initial reaction between powder and liquid is rapid and exothermic, so powder is added slowly in small increments with adequate spatulation between increments to neutralize part of the acid before the majority of the powder is incorporated. If large increments were added, the total amount of powder that can be incorporated and still achieve a cementing consistency, is much reduced with a consequent increase in solubility and decrease in strength.
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20
Q

Composition of Zinc Oxide Eugenol (ZOE)

A
  • Powder: Zinc Oxide (submicron) & Accelerator (zinc acetate/sulfate)
  • Liquid: Eugenol & Accelerator (acetic acid)
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21
Q

Advantages of ZOE

A
  • Obtundent effect on on pulp

* Good sealing ability

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22
Q

Disadvantages of ZOE

A
  • Lowest compressive strengths

* Highest solubility and disintegration

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23
Q

Typical powder liquid ratio of ZOE

A

4/1

24
Q

Manipulation of ZOE

A
  • The liquid slowly wets the powder. Consequently, extended vigorous spatulation is required.
  • Powder may be added in as large an increment as can be conveniently worked into the liquid.
  • The setting reaction involves the formation of the chelate compound, zinc eugenolate
25
Q

Unique property of ZOE

A

Dilatant – viscosities increase with increasing shear rate (“shear thickening”)

26
Q

Modified ZOE Cements

A
  • Reinforced ZOE cement

* EBA (ethoxy benzoic acid) cement

27
Q

Composition of Reinforced ZOE

A
  • Powder: Zinc Oxide (submicron), Zinc Acetate, Polystyrene Powder
  • Liquid: Eugenol, Acetic Acid, Wood Rosin, Dissolved Polystyrene
28
Q

Properties of Reinforced ZOE

A
  • Similar to ZOE
  • Improved strength
  • Decreased solubility
  • Still too weak for permanent cementation
29
Q

Composition of EBA

A
  • 50-60% of eugenol replaced with EBA
  • Powder: 20-30% silica or alumina
  • Power liquid ratio: 4.5-5:1
30
Q

Advantages of EBA

A
  • Similar film thickness and strength to zinc phosphate

* Low pulpal irritancy of ZOE

31
Q

Disadvantages of EBA

A

• Still too soluble

32
Q

Composition of Zinc Polycarboxylate cement

A
  • Powder: 90-100% ZnO, 0-10% MgO

* Liquid: 32-42% Polyacrylic acid

33
Q

Manipulation of Zinc Polycarboxylate

A
  • Powder and liquid combined rapidly in large increments
  • High viscosity
  • P:L = 1.5-2:1
  • Excess removed as soon as seating is complete
  • Needs to be used before it gets dull
34
Q

Advantages of Zinc Polycarboxylate

A
  • Strength, solubility, and film thickness comparable to phosphate cement
  • Minimal pulpal reaction is comparable to ZOE
35
Q

Disadvantage of Zinc Phosphate

A
  • Very short working time
  • Extra care in surface preparation required for bonding
  • Only cement that does not improve in strength and solubility when optimal P/L ratio is exceeded
36
Q

Composition of Silicate cements

A
  • Liquid: buffered phosphoric acid

* Powder: Acid soluble glass containing many compounds, including SiO2, Al2O3, and F-

37
Q

Composition of Silicophosphate cements

A
  • Hybrid of silicate and phosphate cements
  • Powder: Silicate glass, ZnO, MgO
  • Liquid: buffered phosphoric acid
38
Q

Advantages of Silicophosphate cements

A
  • Type I cements yield suitable film thickness for cementation
  • Fluoride release
  • Translucent
  • Highest strength and lowest solubility
39
Q

Disadvantages of Silicophosphate cements

A
  • Very low inital pH
  • High potential for pulpal irritation
  • Manipulation more critical
  • Film thickness higher than for phosphate cements
40
Q

Glass-Ionomer Cement (GIC)

A

Hybrid of silicate and carboxylate cement

41
Q

GIC classification: luting crowns, bridges, and orthodontic brackets

A

Type I

42
Q

GIC classification: esthetic restorative cements

A

Type IIa

43
Q

GIC classification: reinforced restorative cements

A

Type IIb

44
Q

GIC classification: lining cements, base

A

Type III

45
Q
  • Cementation of castings
  • Adhesive base under composite resins
  • Material of choice for Class-V (cervical) erosion lesion filling material
A

Uses of GIC

46
Q

Composition of GIC

A
  • Powder: Alumino-silicate acid soluble glass (reinforcement), F- ~23%
  • Liquid: 40-50% solution of polymeric acid (adhesion)
47
Q

Properties of GIC

A
  • Low pulpal irritation
  • Adhesive
  • Translucent
  • F- releasing
48
Q

Resin Modified GICs (RMGICs)

A

Hybrid of glass ionomer and resin cements

49
Q

Composition of RMGICs

A
  • Powder: Acid soluble glass

* Liquid: Polyacid with dissolved hydroxyethyl methacrylate (HEMA) and.or grafter methacrylate groups on both

50
Q

Curing mechanism of RMGICs

A
  • Light cured via free radical polymerization (methacrylate groups)
  • Chemical acid-base cure via carboxylate-metal ion mechnism
51
Q

Disadvantages of RMGIC

A
  • Short working time
  • Extra care in surface preparation required for bonding
  • Confusing terminology and names (classification)
52
Q
  • Predominantly for endodontic applications

* Pulp capping & cavity lining

A

Mineral Trioxide Aggregate (MTA)

53
Q

Composition of MTA cements

A
  • Powder: Calcium oxide, Aluminum oxide, Silicon dioxide, Radiopaque filler
  • Liquid: Sterile water
54
Q

Manipulation of MTA cements

A
  • Powder and water on a glass slab ready for mixing
  • Mixture should be puttylike when rolled into a log
  • Log can be cut into pieces for placement
55
Q

Advantages of MTA cements

A
  • Wide range of P:L ratios and viscosities
  • Excellent sealing ability
  • Insoluble
  • Highly biocompatible
  • Initially highly alkaline –> antimicrobial
56
Q

Disadvantages of MTA cements

A
  • Extremely slow setting
  • Initial compressive strength is weaker than ZOE
  • Caustic

Exam 2: DFRD 5001 (1 decks)

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