Dental Materials Y2 > Cavity Lining Materials > Flashcards

Cavity Lining Materials Flashcards

(45 cards)

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1
Q

Describe cavity lining materials

A

Intermediate restorative materials lining the cavity, applied before the placement of the restorative, not temporary but permanent.

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2
Q

What is the purpose of the cavity lining materials

A

Protection, palliative and therapeutic barrier to stop penetration through the dentinal tubules to protect the pulp.

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3
Q

What are the choices we have for using cavity lining materials before we add the restorative

A

Nothing
Cavity varnish
Cavity liner
Cavity base

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4
Q

What are some of the cavity lining material groups that we can use

A
  • Varnishes
  • Calcium Hydroxide cements
  • Zinc oxide based cements
  • Glass ionomer cements
  • Resin modified glass ionomer cements
  • Visible light cured resins
  • Calcium silicate based cements
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5
Q

AY BAWS CAN I HABE DE NOTE PLZ

A

Based on the kind of restorative we use different cavity lining materials to protect the pulp

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6
Q

What kind of pulp protection do cavity varnishes provide

A

Chemical protection

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7
Q

What kind of pulp protection do cavity liners provide

A

Pulp medication

Thermal/electrical protection

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8
Q

What kind of pulp protection do cavity bases provide

A

Thermal/electrical protection

Mechanical protection

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9
Q

What is cavity varnish designed to do

A
  • Seal dentine
  • Reduce diffusion through dentin
  • Decrease microleakage
  • No strengthening
  • Does not bond chemically to dentin
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10
Q

Describe the composition of cavity varnish

A
  • Natural resins e.g. copal
  • Synthetic resins e.g. polystyrene
  • Solvent e.g. alcohol, acetone, ether
  • Some calcium hydroxide and/or zinc oxide
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11
Q

What does cavity liner seal and do

A

Seals exposed dentin

Promotes health of the pulp and adheres to the tooth structure and has antibacterial action

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12
Q

Name some types of cavity liner

A

Calcium hydroxide
Zinc Oxide eugenol
Zinc oxide non-eugenol

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13
Q

What does cavity base do

A 
Replaces dentin 
Blocks out undercuts
Insulation
High strength
Minimises bulk of restorative as it is quite thick
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14
Q

What is an undercut

A

When the cavity goes into the dentin and errr yh the cavity base can fill that

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15
Q

Name some cavity base materials

A
  • Reinforced zinc oxide eugenol
  • Visible light cured resins
  • Zinc phosphate
  • Zinc polycarboxylate
  • Glass ionomer
  • Resin modified glass ionomer
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16
Q

What are the 2 forms of zinc oxide eugenol cement

A

Two paste or powder-liquid form

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17
Q

Describe the composition of the powder component of zinc oxide eugenol cement

A
  • Main component (ZnO/MgO)
  • Fillers SiO2, Al2O3
  • Dicalcium phosphate, mica or rosin - Improves mixing
  • Zinc salt 1% accelerates set
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18
Q

Describe the composition of the liquid component of zinc oxide eugenol cement

A
  • Eugenol or oil of cloves
  • other oils may also modify viscosity
  • Acetic acid 1% - accelerates set
  • Water - small amount - essential to set
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19
Q

Describe the setting reaction of zinc oxide eugenol cement

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A
  • Acid-base reaction
  • Reaction of zinc oxide with eugenol to form zinc eugenolate, a chelate complex
  • Water initiates the reaction and is a by product of the reaction
    ZnO + 2HE ZnE2 + H2O
20
Q

Describe the basic features of the chemical structure of eugenol

Study These Flashcards
A

A substituted phenol

Weakly acidic

21
Q

What will produce a faster and stronger set of zinc oxide eugenol cement

Study These Flashcards
A

Higher powder to liquid ratio and smaller particle size

22
Q

Describe the pH changes in the zinc oxide eugenol setting process

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A

Initial pH of 5.5-6 and then goes up 6-8 in the set cement

23
Q

What are the advantages of zinc oxide eugenol cement

Study These Flashcards
A
  • Easy mix and handle
  • Fast set in the mouth
  • Moisture accelerates set
  • Non irritant pH close to the neutral
  • Obtudant (calming effect on the pulp) when placed on dentin
  • Good sealing characteristics
  • Protects the pulp from chemical irritation
  • Good thermal insulator
24
Q

What are the disadvantages of zinc oxide eugenol cement

Study These Flashcards
A
  • Low compressive and tensile strengthes
  • High water solubility
  • Eugenol is a potential allergen, smells strong and is a mild irritant when in direct contact with the pulp
  • Eugenol inhibits vinyl polymerisation so can’t be used under composites and compomers
25
What are the uses of Zinc oxide eugenol cement
ZOE cements are used in applications where strength isn't important but low irritancy is - Not in direct contact with the pulp - Thermal insulating base - Temporary restorations - Intermediate restorations - Long term cementation - Endodontic use - Periodontal dressing
26
Describe the composition of the powder component of EBA cement
ZnO - 60-75% Fillers - SiO2, Al2O3 - 20-35% Hydrogenated rosin - 6%
27
Describe the composition of the liquid component of EBA cement
- 50-65% of the eugenol in ZOE cement is replaced by o-ethoxybenzoic acid - 35-50% eugenol
28
Is o-ethoxybenzoic acid more acidic than eugenol
yup
29
What are the properties and uses of EBA cements
- Properties similar to ZOE - EBA cements have better strength - EBA cements have lower water solublility - Poor handling characteristics - Uses similar to ZOE cements but used little in reality as other materials are available
30
What are the 2 pastes for calcium hydroxide cements called
Base and catalyst
31
What can the base pastes for calcium hydroxide cements be made of
Salicylate ester 40% e.g. butylene glycol disalicylate Filler e.g. TiO2, CaSO4, BaSO4
32
What can the catalyst pastes for calcium hydroxide cements be made of
Ca(OH)2 50% ZnO 10% Plasticiser 40% e.g. toluene sulphonamide, zinc stearate
33
Describe the calcium hydroxide cement setting reaction
Acid-base reaction: - Disalicylate reacts with Ca(OH)2 and ZnO - Calcium and zinc disalicylate forms
34
What are the advantages of calcium hydroxide cements
- Easy to mix and handle - Rapid hardening in thin layers - Moisture accelerates set - Good seal - Alkaline pH 9-12, can neutralise acid materials e.g. zinc phosphate cements - Antibacterial - Stimulate reparative/sclerotic/ secondary dentin - contact with pulp causes necrosis layer that calcifies - compatible with composites
35
What are the disadvantages of calcium hydroxide cements
- Low strength even when fully set - Weakened by exposure to moisture - Can dissolve completely acid conditions where marginal leakage occurs - Can undergo plastic deformation at mouth temperature
36
What are the uses of calcium hydroxide cement
- Cavity lining, especially in deep cavities, pulp capping - With composites as ZOE cements inhibit setting of composites - Care must be taken when acid etching - Strong enough to withstand amalgam condensation pressures - Thermal insulating agents - Endodontic use
37
What accelerates the setting of ZOE and CH cements
Moisture in the mouth
38
AY BAWS CAN I HABE DE NOTE PLZ
CH cements stimulate secondary dentin formation
39
What is a suspension liner and what is it made of
This is a non-setting, thick layer of a suspension of calcium hydroxide in water. Methyl or ethyl cellulose can be added for strength
40
What visible light cured dental composites can be used as cavity liners
BisGMA UDMA Phosphonated
41
Name some fillers that are used in visible light cured resins
Ca(OH)2 Fluoride releasing glass Hydroxtapatite Calcium Silicate
42
What are the advantages of using visible light cured resins as cavity liners
- Tougher and less soluble - Increased resistance to etchants - Can have alkaline surface pH~11 but not antibacterial
43
What are the properties and uses of Calcium Silicate base or MTA cements
- Mainly used in endodontic applications - High Strength - Alkaline pH - Bioactive pulp repair
44
What is added to reinforce ZOE cements
10-40% of a synthetic resin is added to the powder and coated round the powder particles. Styrene or MMA is added to the liquid.
45
What does reinforcing ZOE cement result in
- Increased compressive strength 40 MPa - Increased tensile strength - Reduced water solubility
Dental Materials Y2
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