Negotiating a perforation of the mesiobuccal canal
Dr Dickon Adams presents a case report describing the treatment of a patient who had been referred to him with a mesiobuccal perforation.
In this particular case, someone referred a 36-year-old female patient to me. Her general dental practitioner was having problems with the root canal treatment on the LL6.
The patient had originally presented to the dentist due to pain. The dentist initiated root canal treatment.
The initial radiograph showed there to be extensive apical areas. I made an association between a mesial radiolucency and a buccal fistula. Also, it revealed slight furcation radiolucency that may have been a result of perforation from the creation of the previous access cavity (Figure 1 and Figure 2).
It also looked as though the instrumentation had failed to negotiate the curved mesial root and had perforated mesially.
Further investigation revealed that there was a large perforation of the mesiobuccal canal (Figure 3).
I discussed the two main treatment options with the patient. These were root canal treatment or extraction, possibly implant placement after that.
After weighing up all the pros and cons of both pathways and the possible implications of each, the patient opted to save the tooth and undergo root canal therapy.
The patient signed the consent form and prepared. The patient understood that successful root canal treatment might not have been possible.
To negotiate the curve and instrument past the perforation, I chose Hyflex EDM root canal files. They are pre-curved and are incredibly flexible, even in hard-to-access canals.
I then confirmed the working length with a radiograph. The electronic apex locator was unreliable, due to the inflammatory tissue and moisture at the site of the perforation. I instrumented the four canals to a size 20 hand file.
Standard nickel titanium files would have been very difficult to use. They would have failed to follow the root curvature. Instead, with their elastic memory, they would’ve followed the iatrogenic canal to the perforation.
However, using a Coltene EDM file, it was possible to negotiate the curve and bypass the perforation. I filed all canals to an EDM size 25, a one-file of variable taper.
In view of the high risk of irrigant leakage, I combined 2% chlorhexidine (CHX) and ultrasonics to irrigate the mesiobuccal canal. The other canals were irrigated with 2% sodium hypochlorite (NaOCl) and ultrasonics.
After an interim dressing with calcium hydroxide (Ca(OH)2), and a symptom-free period, the canals were filled with both gutta percha (Figure 4) and a bio-ceramic root canal sealant (Wellroot-ST).
I intentionally placed sealant into the perforation area in order to create a seal. As expected, an excess of sealant tracked along the fistula channel (Figure 5).
I placed an orthodontic band around the tooth to prevent terminal fracture while allowing time to determine the success of the treatment.
At the 12-month review, the tooth was symptom-free. The radiograph revealed that the mesial areas and furcation area had all resolved. Overall, I am very happy with the outcome relating to this difficult situation.
Furthermore, the excess bioceramic did not seem to be causing any issues. There was no obvious inflammatory response. The bone appeared to have filled in adjacent to it (Figure 6).
There is still a distal radiolucency present. However this has become more defined and, hopefully in time, will fill in further.