Fig. 1

Long cone periapical x-ray showing the guttapercha point inserted in the palatal sinus tract (Fistulography), with inconclusive findings, due to unclear origin.

Fig. 2

Axial plane on the left showing cortical bone loss and a thin hairline consistent with potential VRF, however the coronal plane showed a limited corona-apical extension consistent with a lateral canal.

Fig. 3

Limited apical widening present on the DB root of the UR7. The DB canal was pre-measured on the CBCT as 25.5mm long.

Fig. 4

Master apical cones long cone periapical x-ray showing a good fit of the GP points. 

Fig. 5

Final post-operative x-ray showing infill of the palatal lateral canal on the UR7.


Following local infiltration with articaine and single tooth rubber dam isolation the existing composite restoration, which appeared to be defective, was removed. Necrobiosis was detected with coexisting buccal canals partially vital and pus discharge on the palatal root. 

The pre-measured working length determined on the CBCT scan was utilised due to its high reliability (Paterson et al. 2020). No hand file instrumentation was opted to minimise the chances of ledging and iatrogenic errors: mechanical scouting files have been used linked to the electronic apex locator to confirm full canal patency. A orifice widener has been used in reversed sequence order after the scouting mechanical files with brushing action to minimally countersink the canal orifices. Subsequently the rotary shaping files have been brought to full working length in all canals. A continuous irrigation protocol has been followed (2% NaOCl alternated to 17% EDTA) with activation for 30 seconds for each canal. The MAC LCPA confirmed appropriate taper and WL fit of the guttapercha points. Following sterile paper point drying bioceramic sealer have been deployed in all canals. A further 10 second activation has been carried out in the palatal canal. A hybrid single cone/coronal third backfill obturation technique was opted for. Final LCPA revealed a satisfactory result with infill of the palatal canal. The patient has been reviewed at one month confirming healing of the palatal fistulous tract. Twelve months review will be arranged.


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Gliga A, Imre M, Grandini S, Marruganti C, Gaeta C, Bodnar D, Dimitriu BA, Foschi F. The Limitations of Periapical X-ray Assessment in Endodontic Diagnosis-A Systematic Review. J Clin Med. 2023 Jul 12;12(14):4647. doi: 10.3390/jcm12144647.

Paterson A, Franco V, Patel S, Foschi F. Use of preoperative cone-beam computed tomography to aid in establishment of endodontic working length: A systematic review and meta-analysis. Imaging Sci Dent. 2020 Sep;50(3):183-192.