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 http://dvm360.com/beckman/).

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).

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).

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.

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.

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.

Granulation tissue was debrided and rough bone was smoothed with a curette prior to proceeding with the procedure. Generally 5 mm of root is excised with the aid of a bur on a high-speed handpiece following removal of the bone on the vestibular (lateral) aspect of the root tip. Special tips placed upon a piezoelectric scaler (Photo 3) aid in removing several millimeters of gutta percha to make room for the root-end filling material.

Although a variety of compounds historically have been used to seal the root tip, mineral trioxide aggregate (MTA) is a compound that is now widely accepted as a root-end filling material. Special instruments facilitate mixing and placement. In several hours this biologically friendly cement hardens to seal the root canal (Photo 4).

In this case, a synthetic bone-graft particulate was used to fill the massive void in the bone that was left following removal of the granulation tissue and root-tip removal (Photos 5 and 6).

Resolution of the lesion was rapid. The clients, although not aware of any activity changes prior to surgery, mentioned positive activity and attitude changes three days postoperatively. Radiographic follow-up has not been an option in this case due to owner reluctance in light of continued clinical resolution and other more pressing medical issues.

Root-canal therapy in this case failed to resolve the fistula. It is likely that the degree of bone destruction prior to therapy was so extensive that root-canal therapy would fail regardless. It could be that the perfect fill was not attained, resulting in failure.

Unfortunately, most of our patients with endodontic disease don’t show gross changes like this patient. Radiographic evidence usually is the only way to definitively recognize pulp death with associated root-canal diameter and periapical changes. Keep this in mind when evaluating the dentition of all of your patients. Proper diagnostics will minimize the potential for severe disease and fistula formation as seen in this patient.