Obturation of the Cleaned and Shaped Root Canal

Question 1

What does the filling of the root canal system do?

Answer 1

• 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

Question 2

How is the filling verified?

Answer 2

the completion of root canal preparation is verified by taking a radiograph with the root canal instrument(s) (or filling cones) inserted to the full working length.

This radiograph should show the root apex with preferably at least 2–3 mm of the periapical region clearly identifiable. The prepared root canal should be filled completely unless space is needed for a post.

Question 3

What is the working length?

Answer 3

the distance from a coronal reference point to the point where the canal preparation and filling should end (narrowest point of canal)

Question 4

Where should the WL be?

Answer 4

• WL should be as close as possible to CDJ
• This is usually the narrowest part of the canal – apical constriction

Question 5

How is the working length determined?

Answer 5

computer - detect PDLs resistance of tissues as a current is passed through (EAL)
radiograph

Question 6

What is the WL usually from the apex?

Answer 6

0-3mm

usually increases with age

Question 7

What does >2mm WL of apex increase?

Answer 7

bacteria

Question 8

When should filling take place?

Answer 8

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.

Question 9

What qualities should material used to fill the root canal system have?

Answer 9

biocompatible
dimensionally stable
able to seal
unaffected by tissue fluids and insoluble
non-supportive of bacterial growth
radiopaque
removable from the canal if retreatment needed.

Question 10

What should the filling consist of?

Answer 10

(semi-) solid material in combination with a root canal sealer to fill the voids between the (semi-) solid material and root canal wall.

Question 11

What is the most common core?

Answer 11

gutta percha

Question 12

What is gutta percha?

Answer 12

natural rubber
Trans isomer of polyisoprene

Question 13

What is the composition of gutta percha presentations?

Answer 13

• 20% Gutta-percha
• 65% Zinc Oxide
• 10% Radiopacifiers
• 5% Plasticizers

Question 14

What technique is most commonly used to fill?

Answer 14

cold lateral compaction

Question 15

What are the advantages and disadvantages of cold lateral compaction?

Answer 15

Advantages
Cost-effective: It is less expensive compared to other obturation methods.
Predictable length control: The risk of overfilling the root canal is lower.

Disadvantages
Inhomogeneous fill: It may result in voids and gaps in the root canal filling.
Potential for apical extrusion: There is a risk of forcing gutta-percha beyond the apex.
Less dense fill: Compared to other methods, the resulting fill may be less dense.

Question 16

What is warm vertical compaction

Answer 16

involves heating the gutta-percha to a specific temperature to soften it and then compacting it vertically into the root canal using a specialized plugger.

Question 17

What does warm vertical compaction require?

Answer 17

continuously tapering funnel and minimal apical diameter

Question 18

What is the continous wave obturation technique?

Answer 18

a variation of warm vertical compaction, but with a key difference: instead of alternating between heating and condensing the gutta-percha multiple times, the CW technique uses a single heated plugger to continuously condense the material in a single wave-like motion

Question 19

What is carrier based obturation?

Answer 19

involves using a preformed carrier coated with warm gutta-percha to deliver and place the filling material into the root canal.

Question 20

What happens more in warm thermal techniques?

Answer 20

leakage of gutta percha due to reduced apical control

Thermal techniques are excellent for long-curved canals where it is difficult to place instruments for cold lateral compaction or continuous wave - however it is NOT ideal for long, straight and wide canals as we lack apical control.

Question 21

What other fillers can be used apart from gutta percha?

Answer 21

Bioceramic Cements
Resilon

Question 22

What is resilon?

Answer 22

a thermoplastic synthetic polymer-based endodontic material designed as an alternative to traditional gutta-percha for filling root canals. It’s composed of polyester, bioactive glass, and radiopaque fillers

Question 23

Is resilon better than GP?

Answer 23

no, teeth with RS had 5.7 times greater chance of failure compared to GP

Question 24

Why might MTA be better than GP?

Answer 24

Biocompatibiliy

Antimicrobial properties:

Bonding ability:

May stimulate reparative dentin formation

place at the apex only - wide apical diameter hard to retrieve

Question 25

What are the functions of the sealer?

Answer 25

* Seals space between dentinal wall and core * Fills voids and irregularities in canal, lateral canals and between gutta-percha points used in lateral condensation * Lubricates during obturation

Question 26

What are the properties of an ideal sealer?

Answer 26

* 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

Question 27

What are advantages/disadvantages of ZOE sealer?

Answer 27

Advantages: Resin acids affect lipids in cell membrane thus strongly antimicrobial/cytotoxic Disadvantages: Can act as an irritant Loses volume over time (resins can modifiy this)

Question 28

What are disadvantages/advantages of GI?

Answer 28

Advantages: Dentine bonding Antimicrobial Disadvantages: Greater solubility Removal upon retreatment is difficult Little clinical data

Question 29

What are qualities of resin sealers?

Answer 29

- Epoxy based Resin sealers. - It comes as a past-paste system of mixing and has a slow setting time. - It has good sealing ability which is stable with time and minimal shrinkage over time. - It has initial toxicity but declines after 24 hours following the initial set. | gold standard

Question 30

What are the qualities of silicate sealers?

Answer 30

- High pH during initial 24 hour setting. - Hydrophilic - which provides good penetration into tubules. - It has enhanced biocompatibility (as with any bioceramics) which is useful in the healing process. - Does not shrink on setting, is non-resorbable and as such has excellent sealing ability over time. - Quick set and easy to use. | bioceramic - difficult to retrieve

Question 31

What does the sealer used affect the choice of?

Answer 31

obturation technique

Question 32

What sealers are not recommended?

Answer 32

Sealers containing organic materials such as aldehydes (carcinogen) are not recommended.

Question 33

What are the areas of obturation to assess?

Answer 33

– Length – Taper – Density – Gutta-percha and sealer removal to facial CEJ in anteriors and canal orifice in posteriors

Question 34

Why should the tooth be restored after the RCT?

Answer 34

prevent bacterial recontamination of RC system or fracture of the tooth

Question 35

How does the coronal seal affect the apical seal?

Answer 35

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

Question 36

Where should obturation be finished?

Answer 36

at orifice or just below orifice level

Question 37

What happens if the GP is exposed to oral bacterial?

Answer 37

rapidly becomes infected

Question 38

What materials can be used for a coronal seal?

Answer 38

* ZnO/Eugenol materials are cytotoxic and form effective antibacterial barrier * RM-GI or flowable composite