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3d. BDS3 CDS Endodontics > L21. Obturation of the Cleaned and Shaped Root Canal > Flashcards

L21. Obturation of the Cleaned and Shaped Root Canal Flashcards

1
Q

What is the objective of RCT?

A

To provide and 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

What are the three components to RCT?

[outcome dependent on all three]

A
  • Preparation;
  • Disinfection;
  • Obturation.
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3
Q

Why do we fill the root canal system?

A

To prevent the passage of microorganisms and fluid along the root canal and to fill the whole canal system (apical foramina, dentinal tubules and accessory canals)

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4
Q

Where should the preparation (and therefore WL) end?

A

At the apical constriction - at the junction of pulpal and periapical tissue, as close as possible to CDJ

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5
Q

How can you determine the WL?

A
  • Electronic apex locator;

- Radiographically.

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6
Q

What are the potential problems of using the wrong WL (>2mm short of apex)?

A

Outcomes diminished - significant amount of bacteria left behind

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7
Q

What areas of the root canal system are bacteria/ inflammatory cells sometimes left behind?

A
  • Accessory canals;

- Dentinal tubules.

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8
Q

Obturation is a 2-part system, what are these parts and what do each obturate?

A
  • Core: bulk - sits in canal;

- Seal: penetrates tubules.

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9
Q

How is the timing of obturation usually determined?

A
  • Signs;
  • Symptoms;
  • Pulp status;
  • Periapical status;
  • Difficulty;
  • Patient management.

[often carried out in more than one tx visit: e.g. disinfect/ dress, pt sent away, obturation if symptoms have resolved]

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10
Q

What are the ideal properties of an obturation material?

A
  • Biocompatibility;
  • Dimensionally stable;
  • Able to seal;
  • Unaffected by tissue fluids;
  • Insoluble;
  • Non-supportive of bacterial growth;
  • Radiopaque;
  • Removal from the canal if retreatment needed.
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11
Q

What is gutta-percha (GP)?

A
  • Most common core material;
  • Semi-solid;
  • Produced from juice of trees;
  • Same polymer as natural rubber, isoprene;
  • Trans-isomer of polyisoprene.
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12
Q

What are the constituents of GP?

A
  • 20% GP;
  • 65% zinc oxide (filler);
  • 10% radiopacifiers;
  • 5% plasticisers.
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13
Q

What are the three main types of obturation techniques?

A
  • Cold lateral compaction;
  • Size-matched cones;
  • Thermal techniques (warm vertical compaction/ continuous wave/ carrier-based obturation).
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14
Q

What are the main advantages with cold lateral compaction?

A
  • Most commonly taught;
  • Low cost;
  • Ability to control the length of the fill.
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15
Q

What are the main disadvantages of cold lateral compaction?

A
  • Voids;
  • Spreader tracts;
  • Incomplete fusion of GP cones;
  • Lack of surface adaption.
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16
Q

What are the main advantages of size-matched cones (~single point obturation)?

A
  • Tight apical fit;
  • Easier;
  • Faster.
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17
Q

What are the main disadvantages of size-matched cones?

A
  • Leaves very little space for accessory cones;

- More space as you come coronally; requires more sealer.

18
Q

What’s the main advantage of thermal techniques?

A

Fills spaces (dentinal tubules/accessory canals) much better than cold lateral compaction

19
Q

What’s the main disadvantage of thermal techniques?

A

Require good apical control to prevent extrusion past apex (into periapical area/ nerves/ maxillary sinus)

20
Q

What technique is often used to obturate large, open apexes?

A

Bioceramic cements

[usually to act as an apical plug, then backfilled with GP]

21
Q

What’s the main advantage of bioceramic cements?

A

They provide alkaline conditions which are osteoinductive (cementum/ bone growth alongside)

22
Q

What are the functions of a sealer?

A
  • Seal space between dentinal wall and core;
  • Fills voids and irregularities in canal, lateral canals and between GP points used in lateral compaction;
  • Lubricates during obturation.
23
Q

What are the ideal properties of a sealer?

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.
24
Q

What are the four main types of sealer?

A
  • Zinc oxide eugenol based;
  • Glass ionomer sealers;
  • Resin sealers;
  • Calcium silicate sealers.
25
Q

What are the main advantages of zinc oxide eugenol based sealers?

A
  • Effective antimicrobial;
  • Cytoprotection;
  • Resin acids affect lipids in cell membranes (antimicrobial);
  • Although toxic, may overall be beneficial with longlasting antimicrobial effect combined with cytoprotection.
26
Q

What are the main disadvantages of zinc oxide eugenol based sealers?

A
  • Resin acids affect lipids in cell membranes (cytotoxic);
  • Free eugenol which remains can act as an irritant;
  • Lose volume with time due to dissolution (but resins can modify this);
  • i.e. lacks long-term stability and apical seal can breakdown.
27
Q

What is the main advantage of glass ionomer sealers?

A

Good dentine bonding properties

28
Q

What are the main disadvantages of glass ionomer sealers?

A
  • Minimal antimicrobial activity;
  • Greater solubility (lacks long-term stability);
  • Removal upon retreatment is difficult;
  • Little clinical data to support use.
29
Q

What are the main advantages of resin sealers?

A
  • Long history of use;
  • Paste-paste mixing;
  • Slow-setting (8hrs);
  • Good sealing ability;
  • Good flow;
  • Initial toxicity declines after 24 hours;
  • Hydrophilic;
  • Good penetration into tubules;
  • Biocompatible;
  • Good radio-opacity.
30
Q

What are the main advantages of calcium silicate sealers?

A
  • High pH during initial 24 hour setting (antimicrobial);
  • Hydrophilic;
  • Enhanced biocompatibility;
  • Does not shrink on setting;
  • Non-resorbable;
  • Excellent sealing ability;
  • Easy to use (no mixing).
31
Q

What’s the main disadvantage of calcium silicate sealers?

A

Quick-set (3-4hrs), requires moisture

32
Q

What type of sealer is used in GDH&S?

A

Resin - AH26

33
Q

What is the choice of sealer dependent on?

A

Technique being used e.g. can’t use zinc oxide eugenol sealer with heating GP (not compatible), can use Epoxy/ AH plus

34
Q

After obturation, how should the quality of filling be checked?

A

By radiograph

35
Q

What factors do you check on an obturated root canal, on a radiograph?

A
  • Root apex with 2-3mm of the periapical region clearly identifiable (length);
  • Canal should be filled completely (unless space is needed for a post);
  • 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;
  • Taper;
  • Density.
36
Q

What materials are used for a primary seal, before the coronal restoration?

A
  • Vitrebond;
  • RMGI;
  • RIM (?).
37
Q

Is the apical or coronal seal more important?

A

Both need to be as good as each other for best outcome

38
Q

At what level of the tooth should obturation finish and why is this important?

A
  • At orifice, or just below;
  • GP rapidly becomes infected if directly exposed to oral bacteria;
  • ZnO/ eugenol are cytotoxic and form effective antibacterial barrier.

[make sure finished surface is clear of sealer and GP, using alcohol, as will ensure best application of primary seal/ restoration]

39
Q

What is regenerative endodontics?

A
  • At research level;

- Endodontic treatment that replaces damaged structures like pulp/ dentine by regeneration.

40
Q

What is important to consider (as an individual) for performing routine endodontic treatment?

A
  • One or two techniques/ materials, depending on case;
  • Keep it simple;
  • Respect biological principles;
  • Disinfection and irrigation is key (no filling material or technique can compensate for inadequacy here).

3d. BDS3 CDS Endodontics (8 decks)

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