Patient: 52 year-old female, excellent health

Chief Complaint: Mobility at the first maxillary premolar (tooth #12) and a slight tenderness to palpation

Dental History: The first maxillary premolar (tooth #12) had been endodontically treated many years ago and retreatment was performed in 1992; A crown had been placed by the referring dentist two years prior to the author’s initial examination

Significant findings: slight percussion sensitivity, slight palpation sensitivity, 4mm periodontal pocket with bleeding on the mesial aspect, no tooth mobility although the crown was loosened. A radiolucency was evident in the furcation area. A CBCT revealed an untreated third root (DB) and a perforation on the buccal wall in the palatal canal

Diagnosis: Previous endodontic filling(missed canal and perforation on palatal canal)/Chronic Periradicular Periodontitis

Prognosis: Fair to good (due to periodontal pocket, short roots and great loss of dental structure)

Treatment Plan: Nonsurgical Endodontic Retreatment and Perforation Sealing with MTA (Tooth #12)

Treatment Description and Special considerations:

Access revealed the hidden missed canal and the perforation was at the cervical third of the buccal wall in palatal canal. The gutta percha was removed and the three canals were cleaned and shaped. The perforation was cleaned with ultrasonically activated sodium hypochlorite and filled with MTA. Calcium hydroxide was placed and the crown was temporarily cemented. At the second appointment, the canals were obturated with gutta percha and AH-plus sealer. A resin was bonded coronal to the MTA level in the root.

The sealing of the perforation was simple due to its location, but the presence of a periodontal pocket might affect the long-term outcome. Perforations that are repaired quickly without delay have an improved success rate.

Missed canals may be frequently found on periapical radiographs but in this case it was hidden until revealed on the CBCT scan.

The compromised coronal tooth structure requiring post placement associated with a perforation on palatal root increases the risk of fracture and a less favorable long-term prognosis. The 9 month recall radiograph and clinical exam demonstrated healing (normal sulcular probing depths, normal percussion, normal palpation) and osseous regeneration. The tooth was appropriately restored to function and health with expected stability considering the complications.

Key learning points:

1. The CBCT is an important diagnostic aid and can locate otherwise missed canals

2. Appropriate access is important to treat all canals

3. Copious irrigation and ultrasonics should be used to clean and clear the perforation site

4. MTA effectively seals perforations with predictable osseous regeneration

5. The author recommends treatment in two visits

6. The use of resin coronal to the level of the MTA may be important to increase the resistance and to correct the preparation of canal before placing a post

7. The risk of fracture should be considered in cases like this with extensive loss of tooth structure