Patient: 75 year-old female, hypothyroidism and asthma

Chief Complaint: fistula, sinus tract

Dental History: The patient had history of initial root canal treatment in the 1970’s performed on the maxillary right (#8) and left (#9) central incisors. Retreatment was performed on both teeth in one visit in 1988. The two teeth were restored with casts posts and ceramic crowns in 1989. The patient developed a fistula in December 2016 and was referred to the author’s practice.

Significant Findings: The patient presented with no pain, a draining fistula on the labial aveolar mucosa opposite the root apex of #9. Class 1 mobility was associated with #9 and little or no detectable mobility associated with the adjacent teeth. The periodontal findings for both maxillary central incisors were within normal limits with slight bleeding at the mid-mesial of #9 when probed. Radiographic and CBCT findings demonstrated #9 to be filled short even though the historical radiographs from 1988 showed the apical root bifurcation to be filled to the radiographic terminus. A radiograph taken with a fistula tracing showed the gutta percha tip located at the #9 root apex.

Pulp and Periradicular Diagnosis: Previous root filling with recurrent lesion of endodontic origin (#9); previous root filling with a normal periradicular periodontium (#8)

Treatment Prognosis: Fair to Good (#9)

Treatment Plan: Nonsurgical endodontic retreatment with post removal (#9)

Special Considerations of Performed Treatment:

This case highlights an interesting and commonly seen pattern of long-term endodontic treatment failure

It is currently debated that incompletely debrided and filled root canal systems may be preferable to wide shaping that facilitates apical debridement so that the root is not weakened and predisposed to fracture. This author believes that disease elimination and idealized root canal treatment is preferable but that proper restoration and design of occlusion is essential to eliminate forces likely to cause root fracture that would otherwise be blamed on the endodontic treatment.

The initial root canal treatments on #’s 8 and 9 performed in the 1970’s had obvious deficiencies and the retreatment performed later in the 1980’s served this patient well for nearly 30 years. The survivability of these two teeth were a testament to the quality of the endodontics and the restorations. It can interestingly be suspected that the large apical preparation of #8 led to more complete debridement of the septic debris left from the initial treatment, so that when it was obturated, sealed, then properly restored it remains functional and healthy to date. Conversely, the #9 tooth was retreated with a narrow apical preparation. Even though the apical bifidity was demonstrably filled in 1988, it was washed out and seemed filled grossly short in 2017. This suggests that the apical bifurcations were not completely cleaned and shaped free of septic debris. A gutta percha cone was likely fit to the bifurcation and sealer was hydraulically pushed into the branches through the apex. Eventually the sealer washed out and the remaining titer of communicating pathogens were sufficient to cause recurrent endodontic disease decades later. There had been no change in the restoration of #9 which had been restored similarly to #8 in 1989

Many endodontists would have chosen to perform surgical endodontic retreatment to protect the ceramic crown and avoid removing a hard cast post. The patient was willing to have the crown remade if necessary. Removal of the post and nonsurgical retreatment was judged to be a better option with better cleaning of the entire root canal system. The crown remained intact throughout treatment after the atraumatic post drill out.

After thorough cleaning and shaping the first visit (with copious irrigation and activation with ultrasonics), calcium hydroxide was placed in the root canal system and the access temporized for one month. When the patient returned one month later, the fistula was still present. The root canal system was irrigated, cleaned and shaped with additional ultrasonic activation, and then a dry mix of calcium hydroxide was placed for an additional month. When the patient returned the next month, the fistula had healed. The root canal system was obturated with bioceramic (EndoSequence Sealer) utilizing a ball of Cavit as a piston to plunge into the orifice to push the material precisely to length. Bioceramic was chosen rather attempting to fit a gutta percha cone into the complex bifid root where the resorbable sealer had washed out and led to failure before.

The author prefers a resorbable sealer for routine cases that satisfies Grossman’s root filling requirement of “retreatability” but the next step for this case would have been apical resection and a monoblock of non-resorbable bioceramic would was preferable in case a future apicoectomy is planned.

The Cavit base was left in the canal orifice and a bonded resin filling was placed in the access cavity preparation (Photobond and Luxacore for the bulk fill and then the porcelain etched, silanated, with Optibond Fl and Z250 composite on the surface)

Recall: A recall examination was planned for one year.

Key Learning Points:

1. Apical debridement is essential for long term endodontic healing

2. Narrow apical preparation prevents removal of septic debris which is especially important when retreating a failed endodontic case

3. Bioceramic is an excellent alternative root filling choice when future nonsurgical retreatment will not be considered

4. Nonsurgical retreatment is preferable to surgical retreatment in most cases due to more thorough elimination of contaminants from the entire root canal system

5. Cast posts can be atraumatically drilled out without destroying a ceramic crown

6. Successful treatment outcome is multifactorial requiring proper restorative and endodontic treatment. All phases of treatment need to be performed well to prevent eventual failure