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BDS3 Past Paper By Topic (05-19) > Luting cements > Flashcards

Luting cements Flashcards

1
Q

What are the ideal properties of luting cements for cementation of crown? (2)

A
  • Adhesion to tooth structure
  • Adhesion to restorative materials
  • Adequate strength to resist functional forces
  • Insolubility in oral fluids
  • Thin film thick (ADA specification = 25 μ)
  • Biocompatibility with pulpal tissues
  • Anticariogenic properties
  • Ease of manipulation
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2
Q

What is the ‘chemical bonding’ found in chemically active luting cements (which are used to cement crowns) such as Panavia-F?

A
  • Chemical bond: -Si-O-Si- and -C-C- at the interface (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6657896/)
  • Monomer MDP
  • Panavia-F is a resin cement – components include bis-GMA & EDMA
  • In addition to the micromechanical interlocking between resin cement & tooth enamel (after acid-etching)

between resin cement & crown (after HF etching and/or sandblasting)

there’re also chemical covalent bonds & hydrogen bonds between tooth dentine & DBA

between DBA & resin cement

between resin cement & silane coupling agents, as well as

between silane coupling agents & crown (ceramic or metal oxide)

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3
Q

What is the cement will you use to cement the temporary crown & why (2)

A

Zinc oxide eugenol cement; is fairly easy to break – easier to remove to place permanent crowns + eugenol has sedative effect on sensitive teeth

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4
Q

What is the type of materials in temp bond

A

Base: Zinc oxide, white mineral oil

Accelerator: eugenol
Mix 30 secs ; Working time 1:30; Set: 7min Base (NE, non-eugenol): Zinc oxide, white mineral oil (petroleum)

Accelerator (NE): Octanoic acid; 2-ethoxybenzoic acid; (R)-p-mentha-1,8-diene

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5
Q

What is the type of materials in Poly F Plus?

A

zinc polycarboxylate cement

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6
Q

What is the type of materials in Ketac Cem?

A

Glass ionomer cement

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7
Q

What is the type of materials in Panavia F2.0?

A

Resin cement

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8
Q

Problems with incomplete seating of crown during cementation (2)

A

Occlusal interference; marginal leakage leading to secondary caries

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9
Q

Describe and explain the treatment on dentine surface before using resin cement (1)

A

Etch with phosphoric acid for 15 seconds, then rinse. It can facilitate the infiltration of the acidic resin monomers into the demineralized dentin substrate. (The authors speculate that the increased water content of dentin after phosphoric acid etching helps to better ionize the acidic monomers in these luting agents, permitting an improved surface conditioning and polymer entanglement.)

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10
Q

Luting Cements:

What are the advantages of Zinc phosphate?

A 
Used successfully for more than 100 years
High compressive strength
Low tensile strength
Inexpensive
Good for cast gold
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11
Q

Luting Cements:

What are the disadvantages of Zinc phosphate?

A

Postoperative sensitivity may occur
Relatively low strength + more soluble intra-orally
Cannot bond to tooth structure or restoration (No chemical bonding)

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12
Q

Luting Cements:

What are the indications for Zinc phosphate?

A

Cementation of crowns, bridges, inlays, ortho band.

Cavity lining under amalgam, composite resin.

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13
Q

Luting Cements:

What are the advantages of polycarboxylate?

A

Easy to use
Gentle on the pulp
Chemically bonds to the tooth structure
Little post-operative sensitivity

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14
Q

Luting Cements:

What are the disadvantages of polycarboxylate?

A 
Acid dissolution (not for long bridges)
Low strength
Undergoes plastic deformation
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15
Q

Luting Cements:

What are the indications for polycarboxylate?

A

Crowns, inlays and orthodontic bands
Cavity lining under restorative materials or following RCT
Provisional fillings in deciduous teeth
(Cement is reconstituted by simply adding water with the dropper bottle supplied - easy to mix and use (Anhydrous version eliminates problems commonly associated with conventional Zinc Polycarboxylate cements))

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16
Q

Luting Cements:
What are the advantages of Glass Ionomer?

Ken: an example is 3M ESPE Ketac Cem (Prof Chu ppt)

A
  • Moderate strength
  • Bond with tooth
  • Fluoride release  anticariogenic effects
  • High biocompatibility
  • Thin film thickness (< 25 μm) to optimize fit and marginal integrity
  • Radiopacity ensures good control
17
Q

Luting Cements:

What are the disdvantages of Glass Ionomer?

A

Often demonstrate postoperative sensitivity

Acid dissolution

18
Q

Luting Cements:

What are the indications for Glass Ionomer?

A

Cementing of Cr & Br, inlays, P & C and ortho bands
Cavity lining.

Ken: P&C = post and core?? Not sure

19
Q

Luting Cements:
What are the advantages of RMGI (Approx. 20% glass ionomer / 80% resin)?

Ken: an example is 3M RelyX Luting 2 (Prof Chu ppt)

A 
Good strength
Lower solubility
Low film thickness
Bond with the tooth, release fluoride (but not much)
Little post operative sensitivity
Relatively easy to use
Moisture tolerant (RelyX)
20
Q

Luting Cements:

What are the disdvantages of RMGI (Approx. 20% glass ionomer / 80% resin)?

A

Some versions may expand and crack porcelain (less a problem nowadays)

21
Q

Luting Cements:

What are the advantages of Resin cements (Panavia F 2.0 Dual Care Kuraray)?

A

Good compressive & tensile strength
Resists water & acid dissolution
Gives excellent bond strength

22
Q

Luting Cements:

What are the disdvantages of Resin cements (Panavia F 2.0 Dual Care Kuraray)?

A

Excess material, once set, is difficult to remove
Moisture control needed
Technique sensitive

23
Q

Luting Cements:

What are the indications for Resin cements (Panavia F 2.0 Dual Care Kuraray)?

A

Cementation of:
• Metal crowns, bridges, inlays and onlays
• Porcelain crowns, inlays, onlays and veneers
• Ceramic oxide crowns, bridges, inlays and onlays
• Composite resin crowns, inlays and onlays
• Amalgam bonding

24
Q

Luting Cements:

What are the advantages of Resin cement (RelyX Unicem 2)?

A

Convenient dispensing
Easy removal of excess
Time-saving - no etching**, priming or bonding.

**Selective etching is required to increase surface area for bonding.

25
Q

Luting Cements:

What are the properties of Temporary cement?

A 
Weak physical properties
Enable easy removal of temporary crown
Easy to mix and manipulate
Easy clean-up after removal of temporary crown
Sedative effect on pulp (if possible)
Low solubility
Quick set

Usually use ZOE – (don’t use with resin cement though)
Use zinc polycarboxylate if long term temporary or when retention is limited

26
Q

Briefly describe the setting reaction of Ketac Cem (2)

A

Acid-base reaction

  1. Al2O3-CaF2-SiO2 glass system reacts with polyacid to produce a gel of hydrated silica
  2. The polyacid solution the permits the formation of an ionically cross-linked polymer network, interpenetrating that of the silica gel, with Al & Ca ions forming the cross link

Consisting of 3 overlapping stages
▪ Dissolution: Hydrolysis of glass, releasing Ca2+ & silicate
▪ Gelation: Silicate form silica gel & the Ca2+ chelate with (PA)-, forming the so-called initial set
▪ Hardening: Hydrolysis continues, further releasing silicate & Al3+, which chelate with (PA)- while taking up Ca2+ in the chelation (final set)

27
Q

List one advantage and one disadvantage of Panavia (2)

A

Advantages:

  1. is considered a golden standard –
  2. (MDP )Outstanding bond to all substrates: enamel and dentin, ceramics, porcelain, composite resin and metal.
  3. Lowest leakage as proven by independent studies.
  4. Self-etch system
  5. Virtually no post-operative sensitivity.
  6. Fluoride-releasing and radiopaque.

Disadvantages:
Studies show it may have lower shear bond strength compared to resin cements such as Variolink II and RelyX Unicem

High cost
More difficult to handle & to remove excess
Comparatively more irritating to pulp
Comparatively thicker film

28
Q

Describe the steps for treatment on glassy ceramics before cementing (2)

A

4-10% HF gel for 1-2 minutes

Silane coupling agent application

29
Q

Luting cement table page66-67, application instructions are available but were not asked in exams

A

.

BDS3 Past Paper By Topic (05-19) (24 decks)

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