In Root Canal Treatment, one of the most important factor to determine the success of this procedure is to get the perfect Coronal Seal. It is very important in every Root canal treated tooth as the Seal is the one which is protecting the Tooth from External infective factors like Saliva and other food substances which can lead to intra-canal infections. If you have the perfect obturation material and sealer and you get a perfect seal at the apex, if you are not able to get a proper coronal seal all the infective materials will seap in and lead to secondary infection.
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What are the Causes of Coronal Leakage in Root canal Treated Teeth:
- Dissolution of Restoration material
- Fracture of the tooth
- Fracture of Restoration
- Delay in placing coronal restorative material
- Inadequate thickness of the restoration
- Dissolution of coronal restorative material
Various chemicals used in dental treatments like intra-canal medicaments and bleaching agents also lead to the dissolution of the restorative materials thus leading to seepage and coronal leakage.
There are many restorative materials which have been used to seal the coronal portion of an Endodontically treated tooth. We have been using them individually which increase the chances of coronal leakage drastically so to help counter this Double Seal technique was introduced.
Restorative materials used in Coronal Seal:
- Glass Ionomer
- Resin Bonded Cements
- Intermediate Restorative material
- Dental Adhesives
- MTA – White and Grey
What is Double Seal technique:
This is a technique which involves the use of two restorative materials together to overcome the disadvantages caused by the use of a single restorative material. These materials are used in combination by placing layer after layer to make sure that even if one restorative fails the other protects the coronal seal and keeps it intact. Two to three restorative materials can be used in combination to make sure that a perfect coronal seal is achieved.
Now let us see what are the combinations of Materials used in Double seal technique to get Coronal Seal:
- Glass Ionomer Type II over gutta-percha followed by Light cure Composite Resin as the final seal:
- Cavit over gutta-percha followed by IRM as the final seal
- MTA – Mineral Trioxide Aggregate over gutta-percha followed by Intermediate restorative material as final seal
- MTA – Mineral Trioxide Aggregate over gutta-percha followed by Glass Ionomer Type II as the final seal
- Dycal over gutta-percha followed by Glass Ionomer Type II as the final Seal
Glass Ionomer Type II over gutta-percha followed by Light cure Composite Resin as the final seal:
This is called popularly as the laminate or sandwich technique which was used in restorations primarily to prevent micro-leakage and the same technique and combination can be used here to achieve a good coronal seal.
Firstly place the Type II GIC materials over the gutta-percha material near the opening of pulp chamber and over it you can seal the Access opening preparation with the help of Light cure Composite Resin to shape it and build up the tooth to get the perfect aesthetic appearance if you are not going for a crown.
Cavit over gutta-percha followed by IRM as the final seal:
This combination is much more effective than the GIC + Composite combination as there are many advantages here which will be mentioned later. Firstly you need to place Cavit deep in the pulp chambers where the gutta-percha ends and the rest of the access cavity is filled with IRM restoration.
Coming to the advantages of this material combination, IRM is said to have antibacterial property so any infectious substance coming in contact with the tooth will be killed by the restoration and is also said to be less soluble than other materials along with having less wear and being higher strength.
IRM is cheaper comparatively and the mixing and placement is easier without requiring any high instrumentation etc.
Coming to the inner layer of Cavit near the pulp chambers it is said to prevent any moisture which has seeped into the cavity from reaching the pulp chambers.
So both the restorative materials seem to be the perfect materials for preventing Coronal leakage. But IRM cannot be used as a permanent restorative material as it is non aesthetical.
The other two techniques involving MTA and IRM or GIC have been tested in furcation involvement cases where MTA was used to seal the furcation involvement and a secondary restorative material like IRM or GIC used to get coronal seal.
The combination of Dycal and GIC has been used successfully in Direct and Indirect pulp capping restorative procedures from many years and this technique can also be used here to get a good coronal seal.