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BDS3 Endodontics > Obturation of the cleaned and shaped rct > Flashcards

Obturation of the cleaned and shaped rct Flashcards

1
Q

What is the objective of root canal treatment?

A
  • To provide an environment that allows healing of periradicular tissues so that the tooth is retained as a functional unit in the dental arch
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2
Q

Why do we want to fill the root canal system? (2)

A
  • To prevent the passage of microorganisms and fluid along the root canal and to fill the whole canal system
  • Not only block the apical foramina but also the dentinal tubules and accessory canals
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3
Q

Where should preparation of a root canal end?

A
  • Preparation should end at the junction of pulpal and periapical tissues
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4
Q

Where should the working length of a root canal be close to?

A
  • WL should be as close as possible to CDJ (cemento-dentinal junction)
  • Usually this is the narrowest part of the canal - apical constriction
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5
Q

What do we use to determine the WL? (2)

A
  • Radiograph

- Electronic apex locator (high degree of accuracy)

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6
Q

When using a radiograph to determine WL far away can the radiographic apex be from the anatomical apex?

A
  • Distance is from 0-3mm
  • Varying constriction anatomy
  • Increasing with age
  • Root resorption is a complicating factor
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7
Q

When should filling of the root canal system be undertaken?

A
  • Filling should be undertaken after the completion of root canal preparation and when the infection is considered to have been eliminated and the canal can be dried
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8
Q

What factors affect the timing of obturation of a root canal? (6)

A
  • Signs
  • Symptoms
  • Pulp status
  • Periapical status
  • Difficulty
  • Patient management
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9
Q

What are the ideal characteristics of materials used to fill the root canal system? (8)

A
  • Biocompatible
  • Dimensionally stable
  • Able to seal
  • Unaffected by tissue fluids
  • Insoluble
  • Non-supportive of bacterial growth
  • Radiopaque
  • Removable from the canal of re-treatment required
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10
Q

We usually use 2 materials to fill a root canal. What are these?

A
  • A (semi-) solid material in combination with a root canal sealer
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11
Q

What is the most common core material used to fill the root canal system?

A
  • Gutta-percha
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12
Q

What is Gutta-Percha produced from?

A
  • Produced from juice of trees of the sapodilla family
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13
Q

Natural rubber and GP are polymers of the same monomer. What is the monomer?

A
  • Isoprene

- Trans isomer of polyisoprene

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14
Q

What is the composition of Gutta-Percha? (4)

A
  • 20% GP
  • 65% Zinc oxide (filler)
  • 10% Radiopacifiers
  • 5% Plasticizers
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15
Q

What are the 4 GP obturation techniques?

A

1) Sealer based obturation
2) Sealer with a bit of GP

3) Lots of little bits of GP and some sealer
4) A lot of GP with minimum sealer

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16
Q

What is the most commonly taught and practiced filling technique?

A
  • Cold lateral compaction

regarded as the benchmark against which other obturation techniques are evaluated

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17
Q

What are 2 positives of cold lateral compaction?

A
  • Low cost

- Availability to control the length of the fill

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18
Q

What are the possible negatives of cold lateral compaction? (4)

A
  • Voids
  • Spreader tracts
  • Incomplete fusion of GP cones
  • Lack of surface adaption
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19
Q

What do GP size-matched cones complement?

A
  • File size and shape (used to shape the canal)
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20
Q

What do size-matched GP cones leave very little space for?

A
  • Leave very little space for accessory cones
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21
Q

Which technique was introduced to achieve three dimensional obturation?

A
  • Warm vertical compaction

- Requires a continuously tapering funnel and minimal apical diameter

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22
Q

Explain the process of warm vertical compaction?

A
  • Place a GP cone into the root canal space and severe off using a heated plugger, the coronal portion of the GP
  • This transfers heat to the GP that is then plugged apically
  • Get some sealer passage along the lateral canals and possibly some GP
  • Then sequentially remove using a heated instrument more and more GP with continued apical pressure periodically so remove, apical plug, remove, apical plug etc
  • So eventually an apical plug of GP about 3mm in length
  • Got sealer and GP going into the lateral anatomy
  • Then place pieces of warm GP back on top of this apical plug then you backfill the space to create a complete 3D obturation of the root canal system
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23
Q

What is continuous wave obturation?

A
  • Use of electrically heated pluggers and electrically heated GP in the gun which allows us to remove and deliver GP in a similar fashion to Herb S
  • But this is seen as a continuous wave
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24
Q

Explain the process of continuous wave obturation?

A
  • Have a GP cone fitted and a plugger that is fitted
  • Plugger should go within 4-6mm of the terminus of the preparation
  • Then place the cone with sealer and then severe off the coronal portion using a heated plugger
  • Then followed by some apical packing
  • Then plug a heated plugger into the mass of GP into one continuous motion
  • Continuous wave of compaction
  • The heated tip should be placed within the GP to the point at which it binds apically
  • The apical pressure is maintained whilst the heat is removed
  • The tip cools and the GP cools whilst under apical pressure
  • Then add in a quick burst of heat and then remove the plugger and with it will come the coronal GP mass leaving just an apical plug of GP
  • We use hand pluggers then to plug down the apical portion of GP to create a nice apical seal
  • Then do the back fill - continuous filling of the space using warm GP (using one of the guns)
  • Then apply apical pressure and obturation is complete
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25
Q

Explain the process of carrier-based obturation?

A
  • Another way of obturating the space using GP is carrier-based obturation
  • In this instance we use an oven to warm GP that is held on a stick
  • This allows us to place warm GP into the root canal space
  • Get very effective flow of GP
  • The core of the GP carrier stays within the root canal, this tends to be a modified GP which is firmer that does not melt under the heat
  • Get a really effective fill and not many voids
  • But have to be slightly careful
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26
Q

Why do we need to be wary when using carrier base obturation?

A
  • The carrier technique is great for long, curved canals where it is difficult to place instruments
  • But not good for long, straight wide canals because we lack apical control
  • Concern is that warm flowable GP making up all f the filling that we then extrude GP into the surrounding space
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27
Q

What are vital structures that we need to be wary of if GP extrudes into surrounding structures? (3)

A
  • Maxillary sinus

- Also have to be careful of other vital structures such as the mental nerve and the ID nerve

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28
Q

What are the long term outcomes like for warm and cold obturation techniques?

A
  • Outcomes are not very different
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29
Q

In what situation would it not be possible to use GP to obturate a canal?

A
  • Tooth with large open apex
  • When don’t get nice tapered, funnel shaped prep with good apical diameter to allow us to gain control of our obturation, sometimes we need to step away from GP
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30
Q

What materials might be used to fill spaces or more complex spaces when GP is not acceptable?

A
  • Bioceramic cements
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31
Q

What is a problem with bioceramic cements (MTA)?

A
  • IT is not very easy to remove then from the canal and can be a big problem
  • So would sometimes fill apex with MTA and backfill with GP
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32
Q

MTA is not only biocompatible but it is also Osteoinducted. What does this mean?

A
  • If place MTA next to the tissue what we see is cementum, we see bone growing along side the surface
  • This can be due to the chemistry of MTA with alkaline conditions upon placement and setting
  • This is a really helpful response
33
Q

What is ortho grade MTA obturation very similar to?

A
  • GP obturation with sealers
34
Q

What is Resilon?

A
  • Resin-based system
  • Dentine bonding technology
  • Thermoplastic synthetic polymer based on polymers of polyester containing bioactive glass and radiopaque fillers
35
Q

What are the functions of a root canal sealer? (3)

A
  • Seals space between dentinal wall and core
  • Fills voids and irregularities in canal, lateral canals and between GP points used in lateral condensation
  • Lubricates during obturation
36
Q

What are the properties of an ideal root canal sealer? (11)

A
  • Exhibits tackiness to provide good adhesion
  • Establishes a hermetic seal
  • Radiopacity
  • Easily mixed
  • No shrinkage on setting
  • Non-staining
  • Bacteriostatic or does not encourage growth
  • Slow set
  • Insoluble in tissue fluids
  • Tissue tolerant
  • Soluble on retreatment
37
Q

What are the properties of Zinc Oxide Eugenol based sealers? (5)

A
  • Zinc oxide effective antimicrobial and may afford cytoprotection
  • Resin acids affect lipids in cell membrane thus strongly antimicrobial/cytotoxic
  • Although toxic, may overall be beneficial with long lasting antimicrobial effect combined with cytoprotective effects
  • Free eugenol which remains can act as an irritant
  • Lose volume with time due to dissolution - resins can modify this
38
Q

Why are glass ionomer sealers advocated?

A
  • Due to dentine bonding properties
39
Q

Do glass ionomer sealers have antimicrobial activity?

A
  • Minimal antimicrobial activity
40
Q

How soluble are glass ionomer sealers?

A
  • Greater solubility so loose mass and apical seal over time
41
Q

Is it easy to remove glass ionomer sealers upon retreatment?

A
  • Removal upon retreatment is difficult
42
Q

How much clinical data is there to support the use of glass ionomer sealers?

A
  • Little data
43
Q

What kind of resin is on resin sealers?

A
  • Epoxy resin
44
Q

What kind of mixing do resin sealers need?

A
  • Paste-paste mixing
45
Q

For how long have resin sealers been used?

A
  • Long history of use - development of AH26
46
Q

What is the setting like of resin sealers?

A
  • Slow setting - 8 hours
47
Q

What is the sealing ability like for resin sealers?

A
  • Good
48
Q

What is the flow like for resin sealers?

A
  • Good
49
Q

The initial toxicity of resin sealers declines after 24 hours. What can this cause?

A
  • Can cause some post-op sensitivity
50
Q

What is EndoRez?

A
  • A UDMA resin based realer
51
Q

Is EndoRez hydrophobic or hydrophilic?

A
  • Hydrophilic
52
Q

How well can EndoRez penetrate into tubules?

A
  • Good penetration
53
Q

Is EndoRez biocompatible?

A

Yes

54
Q

What is the radio-opacity like for EndoRez?

A
  • Good
55
Q

What is the pH of Calcium Silicate Sealers during the initial 24 hours of the setting?

A
  • High pH (12.8)
56
Q

Are Calcium Silicate Sealers hydrophobic or hydrophilic?

A
  • Hydrophilic
57
Q

What is the biocompatibility like of Calcium Silicate sealers?

A
  • Enhanced biocompatibility
58
Q

Do Calcium Silicate sealers shrink on setting?

A
  • No
59
Q

Are Calcium Silicate sealers resorbable?

A
  • No
60
Q

What is the sealing ability like for Calcium Silicate sealers?

A
  • Excellent sealing ability
61
Q

What is the setting like for Calcium Silicate sealers?

A
  • Quick set - 3-4 hours - requires moisture
62
Q

Are Calcium Silicate sealers easy to use?

A
  • Yes
63
Q

What s a negative of Calcium Silicate sealers?

A
  • Cost
64
Q

Sealers containing organic materials such as what are not recommended?

A
  • Aldehydes

- Some sealers are highly toxic - not recommended and should not be used

65
Q

What should the quality of the filling of a root canal system be checked with?

A
  • Should be checked with a radiograph
66
Q

The quality of filling of a root canal should be checked with a radiograph. What are we looking for?

A
  • The radiograph should show the root apex with preferably at least 2-3mm of the periapical region clearly identifiable. The prepared root canal should be filled completely unless space is needed for a post. The prepared and filled canal should contain the original canal. No space between canal filling and canal wall should be seen. There should be no canal space visible beyond the end-point of the root canal filling
67
Q

The assessment of obturation is primarily based on post-op radiographs. What are we looking at? (4)

A
  • Length (does it lie within 2mm of radiographic apex)
  • Taper
  • Density (does it seem to be well condensed)
  • GP and sealer removal to facial CEJ in anterior’s and canal orifice in posteriors
  • Somewhat subjective
  • Errors of obturation may be corrected
68
Q

Why should the tooth be adequately restored after root canal filling?

A
  • To prevent bacterial recontamination of the root canal system or fracture of the tooth
69
Q

What is more important in the success of RCT - the coronal seal or the apical seal?

A
  • Technical quality of coronal restoration significantly more important for apical periodontal health than the technical quality of the root canal treatment
70
Q

What are the main factors that affect the outcome of nonsurgical root canal treatment? (2)

A
  • Apical extent of root filling

- Quality of restoration

71
Q

Where should you finish obturation in the root canal?

A
  • Finish at orifice or just below orifice level
72
Q

When does GP rapidly become infected?

A
  • If exposed directly to oral bacteria
73
Q

What is a positive property of ZnO/Eugenol materials?

A

They are cytotoxic and form effective antibacterial barriers

74
Q

What materials can we use to close the orifice?

A
  • ZnO/Eugenol materials?

- RMGI or flowable composite

75
Q

The future of obturation is regenerative endodontics. What is this?

A
  • Biologically based procedures designed to replace damaged structures, including dentin and root structures, as well as cells of the pulp-dentine complex
76
Q

What are vital pulp therapies?

A
  • Manage the compromised pulp but we recruited cells and we allow them to undergo differentiation and ultimately dentine formation
77
Q

What are pulp regenerative therapies?

A
  • Where we have pulp necrosis and we use disinfectants and then try to recruit stem cells from the apical papilla into the space to allow regeneration of pulp tissue
78
Q

What does complete obturation usually contribute to?

A
  • Contributes to success
79
Q

Are assays reliable?

A
  • Not always reliable or relevant

BDS3 Endodontics (8 decks)

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