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Retreatment of a Maxillary Premolar with 3 Roots

Terry Pannkuk, DDS, MScDDiagnostic Puzzles, Diagnostic Puzzles, Complications: Advanced Management, Complications: Advanced Management, Missed Canals, Missed Canals, Sample Cases, Sample Cases, All by Date, All by Date

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Figure 2. Additional preoperative radiograph showing deep distal margin of the crown likely ending on the resin core

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Figure 1. Preoperative periapical radiograph showing a root filling to the radiographic terminus with gross overfilling

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Figure 3. A preoperative CBCT scan saggital capture image shows the anomalous buccal root with a single orifice, mid-root branch that joins in the apical third of the root, then has a bifurcating terminus

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Figure 4. A preoperative CBCT scan frontal capture image shows the previously untreated anomalous buccal canal system

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Figure 5. A preoperative CBCT scan transverse capture image at the mid-root level shows the tri-lobe, 3 canal root form

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Figure 6. Access on the first visit shows that the previous access was misdirected and perforating the distocervical crown area

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Figure 7. This first visit photomicrograph shows discrete Cavit "block-out" bases sealing the cleaned and shaped root canal systems that had been filled with calcium hydroxide

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Figure 8. This periapical radiograph taken at the end of the first visit shows the distal defect filled with Biodentine, the root canal system filled with calcium hydroxide, and a Cavit temporary filling placed

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Figure 9. A photomicrograph taken at the second visit showing the two buccal canals at mid-root filled with calcium hydroxide

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Figure 10. The cone-fit radiograph taken at the second/final visit

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Figure 11. A check radiograph verifying complete root filling prior to restoration of the access

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Figure 12. A photomicrograph showing the cleaned access prep after obturation ready for restoration

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Figure 13. Immediate post-treatment periapical radiograph

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Figure 14. Immediate post-treatment periapical radiograph taken at an off-angle to show the complexity of the three-canal root canal system

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Patient: 29 year-old male with a pancreatic insufficiency taking Pancrelipase

Chief Complaint: swelling and tenderness to touch

Dental History: Previous endodontic treatment (tooth #4) had been performed by a general dentist July, 2020. Discomfort and swelling had never subsided and the patient was referred to the author on 9/18/2020 for examination. There was great concern with the over-filling in the right maxillary sinus.

Significant Findings (#2): Clinical examination normal periodontal probing depths but with bleeding upon probing at the DL and D areas. Percussion elicited a “different” response and palpation of the buccal alveolar mucosa elicited moderate pain. Radiographic examination revealed a suspected open distal margin resting on a composite core. A large radio-opaque mass was noted in the maxillary sinus apical and distal to the #4 root apex. A CBCT scan was taken and it was noted that the tooth had 3 canals with the MB and DB canal systems blocked out and untreated.

Pulp and Periradicular Diagnosis (#4): Previous root filling of the palatal root, acute alveolar abscess (recurrent endodontic pathosis)

Treatment Prognosis: Fair (#4)

Treatment Plan: Nonsurgical endodontic retreatment with repair of distal ledge/perforation at the distal crown margin (#4)

Special Considerations of Performed Treatment:

Management of a three canal maxillary bicuspid requires careful consideration of buccal root anatomy because the individual MB and DB roots tend to be very narrow and the risk of strip perforation is high. The patient delayed treatment until February 2021 at which time the symptoms of swelling and pain had worsened. The referring dentist was greatly concerned about the gross overfilling of material and expected a surgical retreatment plan. The overfilling was actually a red herring and the failure of the previous endodontic treatment was primarily due to the untreated buccal root and lack of anatomical understanding.

First treatment visit (2/10/2021):
The ceramic crown was accessed and the palatal canal was the first canal to be identified. The access was directed toward the mesial to completely remove the bonded resin covering over the untreated buccal canal orifice. The previously filled mesial ledge was prepared and there was a small opening of the mesial crown margin which was subgingival. The buccal root canal system was noted to have a mid-root bifurcation which joined apically and then branched again with two separate portals of exit at the terminus. Each were cleaned shaped and filled with calcium hydroxide. The palatal canal root filling was removed and the palatal canal was cleaned, shaped and filled with calcium hydroxide. Small Cavit balls were placed to seal the palatal and buccal canal orifices, then Biodentine was placed in the mesial ledge defect. A Cavit temporary filling was placed on top of the Biodentine base as an occlusal seal with no spacer.

Second treatment visit (3/10/2021):
The temporary filling was removed and the P, MB, and DB were cleared of calcium hydroxide. The Biodentine was confirmed to have set hard. Final cleaning and shaping with cone-fitting in all canals was performed and the root was filled via the vertical compaction of warmed gutta percha technique. A central core was placed using Luxacore bonded with Photobond. The surface was cut back and the porcelain etch with hydrofluoric acid, then treated with silane, and an esthetic surface was placed with Filtek Ultrasupreme bonded with Optibond FL.

A recall examination was scheduled at one year.

Key Learning Points:

  1. Careful examination of preoperative radiographs and a CBCT scan is necessary to prevent missing anomalous root canal systems.

  2. Maxillary premolars with three roots tend to have curved, narrow buccal roots with a small furcation area at risk of perforation.

  3. Overfilling is rarely a cause of endodontic failure. Untreated root canal space harbors pathogens and can perpetuate a periradicular abscess via communicating portals of exit.

  4. Biodentine and other similar calcium silicate bioactive filling materials maintain an excellent tissue response constantly releasing hydroxyl ions and maintaining periodontal attachment. Biodentine uniquely has favorable strength properties and is unlikely to resorb once set.

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