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ENDO > Seminar 6: Sealers & Obturation > Flashcards

Seminar 6: Sealers & Obturation Flashcards

1
Q

Acc to NOUM and CHANDLER 2002 What are the two functions of temp fills?

A
  • prevent seepage of canal medicaments
  • provide adequate seal preventing ingression of bacteria and organic materials from oral cavity
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2
Q

Acc to NOUM and CHANDLER 2002, what are the benefits of placing cotton wool in access cavities?

A

-prevents risk of damage to tooth structure upon re-entering
-prevents material being lodged into canals
-

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3
Q

Acc to NOUM and CHANDLER 2002, what are the disadvantages of using cotton pellets?

A
  • reduced thickness of temp material
  • compromise stability of temp rest as acts as a cushion
  • compromise adaptation to walls
  • cotton fibres may adhere to cavity wall acting as a wick causing contamination
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4
Q

Acc to NOUM and CHANDLER 2002, how should cotton pellets be placed?

A

-small pellet over orifice only

-

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5
Q

What is obturation?

A

Impermeable seal
Entomb residual bacteria
Prevent re contamination

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6
Q

What effect does coronal restoration have on success ?

A

Chu et al 2005
Extra coronal had higher success rate
Swartz et al 1983
Higher success for satisfactory restorations than non satisfactory

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7
Q

What types of obturating materials are used?

A

Solid forms:
Historically silver points
GP
Polymer based eg resilon

Pastes/cements:
Historically: RF paste: formaldehyde + resorcinol white crystalline powder. Benefits: destroys infection and ‘resinifies’ residual pulp tissues, but it also obturates the canals as it sets ‘brick’ hard, preventing further reinfection.
advantage: bactericidal effect, is that it permits incomplete pulp tissue removal at the stage of cleaning and shaping
Calcium silicate cements eg MTA

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8
Q

What is GP?

A

Polymer

Composite material

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9
Q

What are the phases of GP

A

Alpha
Beta
Gamma

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10
Q

The two crystalline phases of GP are?

A

Alpha and beta

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11
Q

What are the organic and inorganic components to GP?

A

Organic : polymer (cis and trans isomers) and wax/resin (reduces brittleness)
Inorganic : ZNO (enhances cross linking between polymer chains) and Metal sulphate (opacifiers)

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12
Q

What percentage does GP shrink after heating

A

1-2%

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13
Q

Why do you need to ensure constant apical pressure during cooling of heated GP?

A

To account for volumetric shrinkage

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14
Q

What is the tolerance allowed for GP?

A

0.5mm up to ISO 25
0.7mm above ISO 25

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15
Q

What is an example of polymer based obturating material

A

Resilon

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16
Q

How did resilon work?

A

Combination with a sealer creating a monobloc

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17
Q

What were the downfalls of resilon

A

Bonding to root dentine remains difficult

Eventually it would breakdown creating voids

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18
Q

Why do bioceramics require water ?

A

To release CaOH ions

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19
Q

What does the CaOH from calcium silicates react with to form HAP like crystals?

A

Phosphate ions

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20
Q

Why are calcium silicates so good at encouraging healing?

A

Immune cells recognise the HAP crystals and allows bone to stick to it

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21
Q

What are sealers ?

A

Radiopaque luting agent
Used in combination with solid or semi solid materials
To fill voids
Berman 2021

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22
Q

Why do we use sealers ?

A

Fill voids
Improve seal between filling and root dentine
Lubricate during GP placement
Entomb Bactria

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23
Q

What are some ideal features of sealers?

A 
Radiopaque 
Bacterial 
Biocompatible 
Good handling features
Low solubility
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24
Q

According to McMichen et al 2004 what are the main groups of sealers?

A

Rosin-Chloroform (not used)
ZnO eugenol : antimicrbial activity and good working time (tubliseal)
GIC: adhered to dentine but can dissolve before setting (ketac-endo)
CaOH : uncertain sealing ability, antibac (sealapex)
Polymer based eg AH plus , good flow but can make retreatment Difficult due to low solubility

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25
Q

What are the advantages of GP

A

Radiopaque
Readily available and inexpensive
Softened by heat and solvents
Adapts to irregularities

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26
Q

What are the disadvantages of GP?

A

Cytotoxic
No adhesive qualities
Can evoke foreign body reaction esp in particulate form

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27
Q

What are the benefits of silver points ?

A

Dimensionally stable

Radiopaque

28
Q

What are the risks of silver points

A

Corrode leading to leakage

Lots of voids and heavily reliant upon sealer

29
Q

What are the two types of extrusion that can occur in obturating ?

A

Over filled: well compacted but long

Over extended : voids and long

30
Q

What are some of the ideal features of sealers set out by Grossman 1981?

A

BRENNS
11 in total
Radiopaque
Easy to mix
No shrinkage when set
Bacteriostatic
Non irritant
Soluble for common Solvents
~~~

31
Q

What are the risks of ZNO sealers ?

A

May stain
Inhibits polymerisation of resins
Can have prolonged inflammation

32
Q

Why was AH 26 stopped?

A

Release formaledehyde

Now we used AH +

33
Q

What are the downsides of resin sealers ?

A

Root canal has a high C factor increasing stresses

34
Q

What is the benefit of using orifice plugs?

A

Yamauchi et al 2006

Orifice plugs in dogs found that least amount of inflam seen in those with IRM plugs

35
Q

What are the risks of LC GIC over GIC

A

Less fluoride release and reduced bond strength

36
Q

What is the benefit of using CaPhosphate eg cavit as a temp?

A

Easy to manipulate

Good marginal seal

37
Q

What is the risk of using CaPhosphate eg cavit as a temp?

A

Water sorption leading to poor sealing ability

Better for small cavities

38
Q

What natural substance is GP made from?

A

Coagulated sap of tropical trees found in South America, Singapore and Indonesia (amongst others)

39
Q

Which other material is the structure of GP similar to?

A

Natural rubber (cis poly isomer of polyisoprene)
GP (trans poly isomer of polyisoprene)

40
Q

What are the names of the chemical groups in the trans GP formation?

A

CH2
Methylene

41
Q

What colour is GP naturally ?

A

White

42
Q

What crystalline form does GP naturally occur in?

A

Alpha

43
Q

What temperature does alpha GP become amorphous and melted?

A

> 65 degrees Celsius

44
Q

What happens if you cool heated GP quickly ?

A

B form recrystallises

45
Q

Most commercially available GP is in what form?

A

Beta

46
Q

What happens if you cool heated GP slowly?

A

Alpha form recrystallises

47
Q

What temperature does beta form become amorphous?

A

56 oC

48
Q

What at the properties of alpha GP?

A

Brittle at room temp
Low viscosity when heated

49
Q

Which obturation methods work best with alpha GP?

A

Heated/warm techniques

50
Q

What are the properties of beta GP?

A

Flexible at room temp
High viscosity when heated

51
Q

What obturation methods work well with Beta GP?

A

Cold later compaction

52
Q

What factors makes GP more brittle?

A

Light exposure
Air exposure

53
Q

What chemical process happens to make GP more brittle ?

A

Oxidation

54
Q

At what temperature does GP begin to degrade ?

A

95 degrees celsius

55
Q

What is the benefit of zinc oxide in GP?

A

Increases brittleness

56
Q

What physical forms of GP exist ?

A

-Solid core GP points (ISO and Non ISO)
-Thermo-plasticised
-Cold flowable GP

57
Q

How does cold flowable GP work?

A

Powder form GP and mixed with a resin sealer in a capsule

58
Q

What specific modifications exist to GP to enhance its sealing and therapeutic effects?

A

-Non ISO
-Surface modified eg resin coated/GI coated
-Medicated GP eg CaOH/CHX
-Nanoparticles enriched eg Silver

59
Q

What is the benefit of CHX impregnated GP points ?

A

-CHX is a positive charged molecule and interacts with the negative charged phosphate groups on bacterial cell walls
-CHX can penetrate bacterial cell wall and affect osmotic equilibrium

60
Q

What two microbial species is CHX impregnated GP points effective against ?

A

Candida albicans
E feacalis

61
Q

What is the benefit of the silver nano particles in GP?

A

Silver ions have a long term sustained release which are antibacterial and low bacterial resistance

62
Q

How does glass ionomer bond with dentine ?

A

Ionic bond

63
Q

What is the benefit of using a glass ionomer coated GP cone ?

A

It is not degraded by any residual NaOCl

64
Q

Other than obturation what other dental uses for GP are there ?

A

Pulp tests: heated GP
GP tracer
Dynamic irrigation
Temporisation of access cavity

65
Q

Define microleakage

A

clinically undetectable passage of bacteria, fluids, molecules or ions between a cavity wall and the restorative material.
Shrethsta et al 2010

66
Q

What sealer was resilon used in conjunction with?

A

Epiphany resin
Primer which exposed the collagen fibres of dentine
Sealer which bonded the dentine to the resilon forming the monobloc

67
Q

What was the issue with resilon and epiphany?

A

The bond formed was susceptible to hydrolysis overtime causing voids to form

ENDO (22 decks)

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