Fig. 1

Preoperative radiographic analysis

Tooth no. 46 was refereed for retreatment because of chronic abscess and repeated appearance of sinus tract.
Apical to old Gutta Percha, no tracing to canal space could be seen - that indicate narrow or sclerotic canals.

We can notice furcal lesion below roots trunk.
Lesion could be of periodontal origin: negative because of normal probing depth.

Lesion could be a result of crack or fracture specially with the presence of metal post in distal root

Lesion could be originated from lateral canal toward the furcation region.

Fig. 2

After restoration removal, old Gutta Percha and old metal post exposed.

Fig. 3

With the use of ultrasonic vibration, the metal post was removed.

Fig. 4

After removal of coronal Gutta Percha from the isthmus, a canal detected in MM region could be misdiagnosed as a perforation .

Thanks to color difference and floor map that recommend a normal anatomy rather than artificially made error.
Also with that kind of less care about quality of treatment it doesn’t seem to show a mismanipulated isthmus during canal locating procedures or shaping.

Fig. 5

All canals cleaned from old GP and ready for managing the narrow mid and apical portions of the root.

Fig. 6

After preflaring using 25 - 06 F1 design, 20 -04 used passively till resistance found.

Manual glide path using size 10 K file till full length.

Mechanical glide path done using 13 - 03 F1 file 

Apical finishing and preparation done using 20 - 04 F1 till full length.

Irrigation activated sonically to avoid injury to root dentin structure using ultrasonics in skinny roots.

Fig. 7

Obturation done to the canals using GP and BC sealer in modified hot technique

Fig. 8

Furcal canal obturated using Putty BioCeramic material

Fig. 9

Final radiographs showing obturation and filling to root canal system

Fig. 10

Radiographic workflow

Case kept under follow up

Conclusions

Preoperative radiograph is very important before starting endodontic treatment

Case difficulty assessment will lead to successful treatment through good planning and selection of the approach technique and sequence of shaping files.

Essential kit files with flat design from Fanta and SIE show good performance during shaping of narrow long canals. 

Knowlege of endodontic anatomy along with floor map guides and color difference is very important to distinguish between normal anatomy and iatrogenic errors.

Bibliography

Krasner P, Rankow HJ. Anatomy of the pulp chamber floor. JOE 2004; 30(1):5. 

Cohen S, Hargreaves K. Pathways of the Pulp 9th ed. Mosby, St. Louis, MO, 2006. 

Vertucci, F. J., & Williams, R. G. (1974). Furcation canals in the human mandibular first molar. Oral Surgery, Oral Medicine, Oral Pathology, 38(2), 308–314. doi:10.1016/0030-4220(74)90073-5

Trope M,  Bunes A, Debelian G. Root filling materials and techniques: bioceramics a new hope? Endodontic Topics 2015, 32, 86–96