John Rhodes presents another interactive practical and problem solving solution in endodontics. This month he looks at the non-surgical retreatment of a maxillary lateral incisor with unusual anatomy; a second root and canal.
In this case a young lady was referred for retreatment of her maxillary right lateral incisor (UR2).
The patient reported a low-grade ache from the UR2, which had been root filled five years previously and veneered.
Intraorally there was no buccal swelling or sinus tracts, the tooth was not mobile nor tender to palpation and there were no increased periodontal probing depths that may indicate a crack. The tooth was restorable.
An intraoral paralleling radiograph showed that the root had been obturated with a laterally condensed gutta percha technique. There were minor voids in the root filling material and a small periapical radiolucency.
Tracing the periodontal ligament around the root, an anomaly could be visualised on the mesial aspect. In this situation imaging with CBCT could be justified to better assess the morphology of the anomaly and make location of the canal more predictable.
In Figure 1 a paralleling radiograph showed a failed root filling and potential additional root canal. The patient consented to additional imaging and a small volume CBCT was exposed of the UL2 (Planmeca).
The scan showed a second root and root canal with periapical radiolucency.
In Figure 2 a slice from the small volume CBCT showed a second root and canal.
Treatment options in this case therefore included:
- Non-surgical disassembly and root canal retreatment
- Extraction and replacement with a conventional bridge, implant or denture.
In this case there are two sensible treatment options: non-surgical retreatment or replacement with an implant. An implant would be unlikely to offer a better outcome than restoration of the natural tooth.
To see the video of this case visit: https://youtu.be/DN4zlBCkqvA
Isolation and disassembly
After infiltration with local anaesthetic and placement of rubber dam the composite restoration in the access cavity was removed with a long-tapered diamond bur. There was gutta percha present in the access cavity and this was removed using a large LN bur (Maillefer). A gates glidden bur size 2 was used to remove gutta percha from the coronal two thirds of the main canal, after which it was flushed with 3% sodium hypochlorite. The remaining gutta percha was retrieved by carefully winding a size 30 Hedstroem file to engage it before removing intact.
Location of the additional canal and creation of a glide path
The main root canal was large and there was no need to widen it any further.
Using information gleaned from the CBCT Image the orifice of the second canal could be detected. A micro-opener was used to widen the orifice, followed by a small rotary orifice opener. A size 006 Flexofile (Dentsply Sirona) could be introduced into the canal and a preliminary working length estimated with an electronic apex locator. A glide path was established with a size 10 Flexofile manipulated with watch-winding and small vertical filing motion until the path was reproducible.
The accessory root was very fine. Tapering of the canal had to be conservative to avoid any risk of iatrogenic perforation but still allow adequate irrigant interchange. The canal was therefore tapered in this case using a narrow taper rotary instrument with a size #025 tip.
Figure 3 shows a confirmatory radiograph with good length in both canals. There was some gutta percha remaining at the apex of the main canal that was removed with a hedstroem file.
Disinfection and obturation
The canals were disinfected with 3% sodium hypochlorite solution activated with a small Endo Activator (Dentsply Sirona). After disinfection the case was obturated using a bioceramic sealer (BioRoot RCS, Septodont) and single cone gutta percha. The sealer was injected into the coronal portion of the root canal and the cones seated to length before searing off at the level of the pulp floor and compacting with a cold Machtou plugger.
Coronal seal
The coronal access was sealed with a dual-cure composite (Core-X flow Dentsply Sorona) after full etching and bonding with a dual-cure bonding agent (Prime and Bond Universal Dentsply Sirona).
Figure 4 shows the completed root canal treatment. One can see a good coronal-apical seal.
To recapitulate…
- It is always prudent to have a systematic approach to examining radiographs. Unusual things can happen and being thorough means they will not be missed.
- Three-dimensional imaging in the form of CBCT can be invaluable for pre-assessment. Every exposure has to be justified and CBCT is not required for all endodontic procedures. In this particular case it made location and visualisation of the accessory root and canal more predictable and avoided unnecessary removal of dentine whilst trying to locate the minor canal orifice.
- If the canal is very fine the operator may need to adjust the preparation protocol, using a narrower taper final instrument that widens the canal sufficiently for irrigation but does not weaken it unnecessarily.
- Single cone and bioceramic sealers can be used in cases where the canal is fine and it may be difficult to fit pluggers used in vertical compaction techniques.
To see how these steps were applied visit: www:youtu.be/DN4zlBCkqvA or search YouTube for john rhodes endo unusual anatomy UR2
This article first appeared in Endodontic Practice magazine. You can read the latest issue here.
