Cavity Lining Materials Flashcards

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1
Q

what are some disadvantages of restorative materials?

A
  • may not make intimate contact with the tooth surface
  • heat release during setting/curing
  • release of chemicals (pulpal irritants)
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2
Q

what is the function of a lining material used in conjunction with restorative materials?

A
  • prevents gaps

- acts as a protective barrier

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3
Q

what is the difference between a cavity base and a cavity lining?

A

Cavity base = thick mix placed in bulk (dentine replacement)

Cavity lining = thin coating over exposed dentine

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4
Q

what is the purpose of a liner?

A
  • pulpal protection
  • therapeutic/calm down inflammation within pulp
  • palliative to reduce patient symptoms prior to definitive treatment being carried out
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5
Q

what does a liner protect the pulp from?

A
  • chemical stimuli in the filling material (initial pH of material also)
  • thermal stimuli (exothermic setting & heat conduction of materials)
  • bacteria and endotoxins (microleakage)
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6
Q

what are the ideal properties that should be seen in a lining material?

A
  • easy to use (mix, long working time, short setting time)
  • low thermal conductivity
  • should match the thermal expansion coefficient of tooth
  • low thermal diffusivity
  • high compressive strength
  • similar modulus to dentine
  • radiopaque
  • LOW solubility
  • fluoride releasing/antibacterial
  • biocompatible
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7
Q

explain the ideal usage tendencies of a lining material that are desired?

A
  • easy to mix
  • long working time
  • short setting time (command set ideal)
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8
Q

why is it important that the thermal conductivity of a lining material is low?

A

to prevent heat expelled from exothermic reactions/conduction of heat through metal materials irritating the pulp

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9
Q

what is meant by the thermal expansion coefficient of a material?

A

the change in length per uni length for a temperature rise of 1°C (ppm°c^-1)

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10
Q

what should the thermal expansion coefficient of a lining material be?

A

should try to match the thermal expansion coefficient of the tooth

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11
Q

what is the thermal expansion coefficient of enamel and dentine?

A
enamel = 8.3ppm°C^-1
dentine = 11.4ppm°C^-1
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12
Q

why is it important that lining materials have high compressive strength properties?

A

to allow placement of filling without it breaking

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13
Q

what is an example of a liner material?

A

setting calcium hydroxide

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14
Q

what is an example of a base material?

A

zinc oxide based cements

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15
Q

what is an example of a material that can be used as a cavity base OR liner??

A

glass ionomer & resin modified glass ionomer

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16
Q

what are the two main constitutes of setting calcium hydroxide liner?

A

base & catalyst

17
Q

what is the setting calcium hydroxide liner base aspect composed of?

A
  • calcium hydroxide
  • zinc oxide
  • zinc stearate
  • N-ethyl toluene sulphonamide
18
Q

what is the setting calcium hydroxide liner catalyst aspect made up of?

A
  • butylene glycol disalicylate
  • titanium dioxide
  • calcium sulphate
  • calcium tungstate
19
Q

what is the setting reaction of a setting calcium hydroxide liner?

A

a CHELATION reaction between the ZnO and the butylene glycol disalicylate

20
Q

what is the initial setting calcium hydroxide liner cement’s pH?

A

around 12

21
Q

what are some positive properties of CaOH liner?

A
  • quick setting time
  • radiopaque
  • easy to use
22
Q

what are some negative properties of CaOH liners?

A
  • low compressive strength

- unstable and soluble (if cavity leaks then the lining will disappear)

23
Q

what are some uses of Zinc Oxide Eugenol (ZOE) Cements and related materials?

A
  • linings/base in deep cavity
  • temporary restorations
  • root canal sealer
  • periodontal dressings
24
Q

what are some properties of zinc oxide eugenol?

A
  • adequate working time
  • relatively rapid setting time
  • low thermal conductivity
  • low strength (20MPa)
  • radiopaque
25
Q

what is the most common material used for lining cavities?

A

glass ionomer

26
Q

why are glass ionomer cements ideal lining materials? (in terms of properties)

A
  • low thermal conductivity & diffusivity
  • thermal expansion similar to dentine
  • high compressive strength
  • radiopaque
  • good marginal seal
  • less soluble than other liners
  • fluoride release
  • can bond to composite resin
  • don’t require surface treatment
27
Q

when should calcium hydroxide be used as a liner over glass ionomer?

A

calcium hydroxide should only be used when the cavity approaches the pulp/ pulp is exposed

28
Q

when calcium hydroxide liner is placed, what else also needs to be done before placing final restoration?

A

covered with RMGIC to protect the Ca(OH)2 and prevent dissolution beneath the restoration

29
Q

what are the different zinc oxide based cements?

A
  • zinc phosphate
  • zinc polycarboxylate
  • zinc oxide eugenol
  • resin modified ZOE
  • ethoxybenzoic acid