Obturation of the Cleaned and Shaped Root Canal Flashcards
What does the filling of the root canal system do?
- 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
How is the filling verified?
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.
What is the working length?
the distance from a coronal reference point to the point where the canal preparation and filling should end (narrowest point of canal)
Where should the WL be?
- WL should be as close as possible to CDJ
- This is usually the narrowest part of the canal – apical constriction
How is the working length determined?
computer - detect PDLs resistance of tissues as a current is passed through
radiograph
What is the WL usually?
0-3mm
usually increases with age
What does >2mm WL of apex increase?
bacteria
When should filling take place?
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.
What qualities should material used to fill the root canal system have?
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.
What should the filling consist of?
(semi-) solid material in combination with a root canal sealer to fill the voids between the (semi-) solid material and root canal wall.
What is the most common core?
gutta percha
What is gutta percha?
natural rubber
Trans isomer of polyisoprene
What is the composition of gutta percha presentations?
- 20% Gutta-percha
- 65% Zinc Oxide
- 10% Radiopacifiers
- 5% Plasticizers
What technique is most commonly used to fill?
cold lateral compaction
What are the advantages and disadvantages of cold lateral compaction?
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.
What is warm vertical compaction
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.
What does warm vertical compaction require?
continuously tapering funnel and minimal apical diameter
What is the continous wave obturation technique?
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
What is carrier based obturation?
involves using a preformed carrier coated with gutta-percha to deliver and place the filling material into the root canal.
What happens more in warm thermal techniques?
leakage of gutta percha due to reduced apical control
What other fillers can be used apart from gutta percha?
Bioceramic Cements
Resilon
What is resilon?
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
Is resilon better than GP?
no, teeth with RS had 5.7 times greater chance of failure compared to GP
Why might MTA be better than GP?
Biocompatibility: Known for their ability to interact positively with living tissues.
Antimicrobial properties: Some bioceramics exhibit antimicrobial effects.
Bonding ability: Can potentially bond better to dentin.
Potential for tissue regeneration: May stimulate reparative dentin formation
What are the functions of the sealer?
- 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
What are the properties of an ideal sealer?
- 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
What are advantages/disadvantages of ZOE sealer?
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)
What are disadvantages/advantages of GI?
Advantages:
Dentine bonding
Antimicrobial
Disadvantages:
Greater solubility
Removal upon retreatment is difficult
Little clinical data
What are advantages of resin sealers?
- Good sealing ability
- Good flow
- Initial toxicity declining after 24 hours
- Good penetration into tubules
- Biocompatible
- Good radio-opacity
- Hydrophilic
What are the advantages of silicate sealers?
- High pH (12.8) during the initial 24 hours of the setting
- Hydrophilic
- Enhanced biocompatibility
- Does not shrink on setting
- Non-resorbable
- Excellent sealing ability
- Quick set - three to four hours – requires moisture
- Easy to use
What does the sealer used affect the choice of?
obturation technique
What sealers are not recommended?
Sealers containing organic materials such as aldehydes (carcinogen) are not recommended.
What are the areas of obturation to assess?
– Length
– Taper
– Density
– Gutta-percha and sealer removal to facial CEJ in anteriors and canal orifice in posteriors
Why should the tooth be restored after the RCT?
prevent bacterial recontamination of RC system or fracture of the tooth
How does the coronal seal affect the apical seal?
Technical quality of coronal restoration significantly more important for apical periodontal health than the technical quality of the root canal treatment
Where should obturation be finished?
at orifice or just below orifice level
What happens if the GP is exposed to oral bacterial?
rapidly becomes infected
What materials can be used for a coronal seal?
- ZnO/Eugenol materials are cytotoxic and form effective antibacterial barrier
- RM-GI or flowable composite
