Cements Flashcards

1
Q

What are the uses of dental cements?

A
  • Cavity lining material
  • Luting cements
  • Temporary restorations
  • Endodontics
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2
Q

Name some requirements for cavity lining materials

A
  • Protect the pulp from thermal, chemical or electrical stimuli
  • Ability to flow into cavity
  • Withstand pressure of restorative material on top
  • Radio opaque
  • Compatible
  • Rapid setting time
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3
Q

What does the integrity of cement material depend on?

A
  • Degree of set
  • Material thickness
  • Pressure exerted when placing
  • Amount of surrounding tooth
  • Handling
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4
Q

What are the two pastes for CaOH cement?

A

Calcium hydroxide with zinc oxide

Butylene glycol disalicylate

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5
Q

Are calcium hydroxide cements strong or weak?

A

Weak - less compressive strength

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6
Q

What is MTA composed of?

A
  • Tricalcium silicate
  • Dicalcium silicate
  • Tricalcium aliminate
  • Bismuth oxide
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7
Q

Why does MTA lead to the discolouration of surrounding oral tissue?

A

Bismuth oxide

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8
Q

What does biodentine have in it to increase the reaction rate?

A

Calcium chloride (Accelerator)

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9
Q

Why can biodentine lead to hydroxyapatite formation?

A

Source of calcium release

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10
Q

What are the main requirements for dental luting cements?

A
  • Ease of manipulation
  • Flowable into cavity
  • Long working time with rapid set
  • Low solubility in oral fluids
  • Adequate tensile and compressive strength
  • Adhesion to tooth tissue
  • Radio - opacity
  • Biocompatible
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11
Q

In zinc phosphate cements, what is the concentration of the phosphoric acid?

A

40-70%

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12
Q

Why do we have small amounts of zinc and aluminium within the phosphoric acid used for zinc phosphate cements?

A

Act as buffers

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13
Q

What can we do when mixing zinc oxide and phosphoric acid to alter the reaction rate?

A

1) Warm the pad mixing occurs on
2) Moistures accelerates the reaction
3) Rapid addition of powder accelerates the reaction
4) High powder:liquid ratio

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14
Q

What concentration of poly acrylic acid do we use when mixing up for zinc polycarboxylate cements?

A

32-40%

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15
Q

Why does zinc phosphate cements cause more sensitivity than zinc polycarboxylate cements?

A

Phosphoric acid has a much lower pH than polyacrylic acid

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16
Q

Why is white rosin added to zinc oxide eugenol?

A

To enhance the working time and the strength of the cement

17
Q

Why is zinc oxide eugenol a temporary cement only?

A

It easily hydrolyses to 2 eugenol molecules and one zinc iron

18
Q

Why is the eugenol molecule a free radical sink?

A

Presence of a carbon carbon double bond

19
Q

What can we add to zinc oxide eugenol cements to modify them?

Why do we do this?

A

Added filler particles that are used in composite (silica, quartz).

Overcome high solubility and low strength of normal zinc oxide cement.

20
Q

What are the two barrels in a self adhesive resin cement?

A

Barrel 1 = functional acidic monomers

Barrel 2 = usual composites of resin composites (bisGMA and filler particles)

21
Q

Why is resin cement contraindicated with resin cement?

A

They contain amide co-initiators which can cause a yellowing effect of the veneer.

22
Q

The sealants used in endo treatment need to be what?

A
  • Insoluble in tissue fluids
  • Ability to seal the whole canal
  • Low viscosity, adequate working time and setting over hours
  • Retain the seal over time
  • Good biocompatibility
  • Adequate strength
23
Q

What two forms does GP exist in?

A

Cis and Trans form

Trans used in dentistry

24
Q

For a trans isomer of GP, there is an alpha and beta form. What is the difference in the packing for each?

A

Alpha : used in heat packing as it is thermoplastic so can be softened with heat application

Beta : cold packing technique

25
Q

What are the pros and cons or GP?

A

+ Semi plastic allows for reshaping
+ Biocompatible
+ Radioopaque
+ Can be replaced if needed

  • Lack of malleability makes placement hard
  • Ages rapidity and go brittle
  • Needs to be used with sealers
26
Q

What are the 4 main types of sealers used with GP?

A

Zinc - oxide eugenol

Epoxy Resin

Gutta percha dissolved

Cements - GIC, zinc polycarboxylate, zinc phosphate