The last article in this case presentation outlines the potential options for resolution of an unusual gingival lesion (first
presented in the June and August issues and available at
Photo 1: The completed root-canal procedure shows a radiographically adequate canal fill.
Root-canal therapy and extraction options were given to the client, and root-canal therapy was desired to retain the tooth
and avoid surgery. Although root-canal therapy is very successful, not all cases respond; additional therapy may be required.
Pet guardians must be made aware of this.
Root-canal therapy was performed on this patient using rotary instrumentation. The result was radiographically sound with
no voids and a good fill of the apical (root-end) portion of the canal (Photo 1).
Photo 2: Cast-metal alloy crowns protect the access site and eliminate crown wear if continued trauma is anticipated.
Gutta percha is represented by the radiodense material within the root-canal system. Please see the June 2009 article for
a basic overview of root-canal therapy. No air or instrument voids are present within the gutta percha. Prognosis is good
for resolution of the fistula and eventual resolution of the defect. Radiographic follow-up should be recommended at six months
and at 12-month intervals until resolution of the bone lucency is documented.
Cast-metal alloy crowns generally are recommended for most root-canal procedures to protect the access site composite
from breaking down and allowing microleakage of oral fluids into the pulp cavity (Photo 2).
A major reason for root-canal failure is the inability to achieve a good, sterile seal at the apex through proper cleaning,
shaping and obturation. Microleakage at the access site on the crown is another major reason for failure of root-canal procedures
in humans and veterinary patients.
Photo 3: Special retrograde endodontic tips are available for removing obturation material (gutta percha) during surgical
root-canal procedures. This demonstrates the surgical endodontic tip cleaning the root end in preparation for the filling
Cast-metal alloy crowns help minimize the potential for access-site failure. Crown placement in this particular case was discussed.
The recommendation for this patient was to wait until short-term resolution of the fistula could be documented and radiographic
evidence of bone fill within the existing radiographic lucency could be appreciated.
Despite recommendations for radiography at a six-month follow-up, the patient returned 11 months later for another problem.
The fistula had not resolved. Radiography revealed lack of bone fill in the periapical region.
Photo 4: This demonstrates the final root end fill with mineral trioxide aggregate.
Exploring the options
Now what are our options? Extraction is one very viable one. Redoing the root-canal procedure is certainly an option. Although
the radiographic appearance suggests that the obturation is adequate, this does not ensure the perfect outcome.
A surgical root canal is a third option. A surgical (retrograde) approach will allow for immediate visual removal of all diseased
periapical tissue including a portion of the root tip. This approach carries a higher possibility for success in this case.
Surgical root-canal therapy is accomplished by approaching the root-canal system through an incision over the bone at the
root tip. The radiographically visible void in the bone generally represents granulation tissue, as was the case here. Cysts
and abscesses are possible but are much less common. The diseased tissue in this case was extensive.
Photo 5: The surgical access location at the root tip shows synthetic bioglass placed following the surgical root canal to
form a scaffold for new bone growth.