Broken file management with Er:YAG laser and SWEEPS

Dr Bartłomiej Karaś

Fri. 12. July 2024

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Broken file management is one of the most challenging parts of endodontic treatment. Regardless of whether the clinician is faced with a retreatment involving retrieval of the broken file or with a file breaking during the primary root canal preparation, the situation usually affects the success rate of treatment.

As is well known, one of the most important factors in root canal treatment is the eradication of the biofilm. The broken file is not a problem per se, but it is an obstacle to proper disinfection. In some cases, removing the broken file requires sacrificing a large amount of very precious peri-cervical dentine. Therefore, in every case, the clinician has to consider all the benefits and disadvantages of the retrieval and decide whether is it worth removing the broken file, leaving it in place or trying to bypass it.¹

The advantages of SWEEPS technology

As mentioned, one of the most important factors of endodontic treatment is root canal disinfection. Usually around the broken file, there is a great deal of accumulated hard-tissue debris, and if the broken file is located in the middle part of the root, the disinfection of the apical part of the canal may be insufficient.

The novel SWEEPS (shock wave-enhanced emission photoacoustic streaming) irrigation technique offers the clinician an easier and more predictable means of managing broken files. The basic principle of the technology is the delivery of synchronised pairs of ultra-short pulses, which create primary cavitation in the vicinity of the fibre tip, followed by secondary cavitation in the remote, difficult-to-reach apical areas. This phenomenon creates shock waves that spread in all directions at a speed of up to 10 m/s—so the impulse reaches 10 mm in depth in just 0.001 seconds.²Moreover, the available data shows that the removal of accumulated hard-tissue debris with the Er:YAG laser is very efficient³and three times more efficient than passive ultrasonic irrigation.⁴

Fig. 1: Pre-op radiograph. Periapical lesion and broken file visible.

Fig. 2: Pre-op CBCT scan. Broken file far beyond the canal curvature.

Fig. 3: Pre-op CBCT scan. Tip of the broken file located below the junction of the mesiobuccal and mesiolingual canals.

Case 1

The patient was referred to the office after failure to retrieve a broken file. After enlarging the canal and attempting to remove the file, the previous operator gave up the treatment. The tooth was symptomatic, so the patient wanted to proceed with the file retrieval and root canal treatment.

The periapical radiograph and the CBCT scan revealed that the file had broken far beyond the curvature in the mesiobuccal canal and below the junction with the mesiolingual canal. Also, a periapical lesion was visible around the apices of the mesial and distal roots (Figs. 1–3). The length of the file was approximately 5 mm. Bypassing the file through the mesiolingual canal would have been a risky procedure because it may have caused the fracture of the second instrument and the obturation may also have been very challenging. Thanks to SWEEPS technology and a bioceramic sealer, an alternative approach could be taken. After administering anaesthesia and placing a dental dam, the temporary restoration was removed (Figs. 4 & 5). The pulp chamber was rinsed with 5.25% sodium hypochlorite and the irrigant activated with ultrasonics. After cleaning the chamber of the tooth, the dental dam and clamp were rinsed with water and dried and flowable dental dam was placed to seal the tooth and enlarge the space in the pulp chamber for the laser-activated irrigation (Fig. 6). Activation was performed with the SkyPulse laser (Fotona). The AutoSWEEPS mode was chosen. The power of activation was set to 1 W. The flat SWEEPS 300/20 fibre tip was used (Fig. 7). The tip was placed slightly below the orifice of the mesiobuccal canal for the majority of the irrigation with sodium hypochlorite. After 120 seconds of activation with sodium hypochlorite, the tip was placed in the pulp chamber to activate the sodium hypochlorite in all the canals simultaneously for 30 seconds. This procedure was continued for 30 minutes. Only the distal canal was shaped with rotary files, up to size 40/.04. Both mesial canals remained the same size as they were before the file broke during the primary treatment. Finally, the canals were flushed with EDTA activated with AutoSWEEPS at a power of 0.4 W, and sodium hypochlorite was activated for three cycles with AutoSWEEPS at a power of 0.6 W and with a 30-second break for the resting phase. The irrigant flow between the mesiobuccal and mesiolingual canals was rapid, indicating that obturation could be performed.

The canals and chamber were dried with micro-suction and paper points (Fig. 8). A bioceramic sealer (CeraSeal, META BIOMED) was used in the piston technique. The sealer was injected in all canals and covered with flowable gutta-percha in the orifices (Fig. 9). Periapical radiographs were performed, and they revealed that the root canals had been filled correctly, showing puffs of sealer in the periapical area (Figs. 10 & 11).

Fig. 4: Treated tooth after dental dam isolation. Damaged temporary restoration.

Fig. 5: Tooth after removal of the temporary restoration.

Fig. 6: Tooth after removal of the caries and sealing of the chamber with flowable composite and dental dam.

Fig. 7: Fotona 300/20 laser tip.

Fig. 8: Pulp chamber after the irrigation protocol.

Fig. 9: Pulp chamber after obturation with the piston technique.

Fig. 10: Post-op radiograph. Puffs of the sealer visible.

Fig. 11: Mesially shifted post-op radiograph.

Case 2

The patient came to the office because of moderate pain connected with the mandibular right first molar. A periapical radiograph and CBCT scan were performed. The images revealed radiolucency around the mesial root of the molar. Also, two pieces of a broken instrument were visible, one in the middle part of the root, before the curvature, and the other slightly below the curvature (Figs. 12 & 13).

Fig. 12: Pre-op CBCT scan. Periapical lesion visible.

Fig. 13: Pre-op radiograph. Two pieces of the broken file visible.

After administering anaesthesia and placing a dental dam, the composite restoration was removed, and a temporary restoration with flowable composite and flowable dental dam for the root canal treatment was performed (Figs. 14–17). After removing the filling material from the mesiolingual and distal canals, access to the broken file was performed. The first piece of the instrument was removed with the ultrasonic tip (Fig. 18), and the tip of the second piece of the file then became visible. Unfortunately, the removed file piece broke in the middle and only the coronal part could be retrieved (Fig. 19). Because the apical part of the broken file was invisible and did not emerge from the canal during the irrigation and activation, an attempt at bypassing it was made. Analysis of the CBCT scan did not reveal a clear answer as to whether there was one apical foramen, so during the bypass procedure through the mesiolingual canal, a periapical radiograph was performed. The radiograph indicated that either there was a ledge in the apical area or there were two separate apical foramina (Fig. 20). For the irrigation protocol, the AutoSWEEPS mode was used at 1.2 W power with the flat SWEEPS 300/20 fibre tip. The tips of both mesial canals were placed below the orifice. The Less-Prep Endo protocol was performed twice in the manner described elsewhere.⁵ After the irrigation, irrigant flow between both canals was rapid.

The canals were dried with paper points and micro-suction (Fig. 21). After the irrigation protocol, there was still a lack of patency and tugback was achieved only in the mesiolingual canal. The mesiobuccal and distal canals were filled with an epoxy resin sealer and warm gutta-percha (squirting technique), and the mesiolingual canal was filled with a 30/.04 gutta-percha cone with the continuous wave of condensation technique (Fig. 22). A distally shifted periapical radiograph was performed (Fig. 23). The radiograph revealed a puff of sealer in the periapical area of the mesial root and the isthmus filled with the sealing material. A composite material was placed into the access cavity, and the patient was scheduled for the control appointment. At six months and 12 months, CBCT scans were performed (Figs. 24 & 25). The images found no signs of inflammation in the periapical area, and the tooth was asymptomatic.

Fig. 14: Treated tooth after dental dam isolation.

Fig. 15: Tooth after removal of the composite restoration.

Fig. 16: Tooth after removal of the restoration.

Fig. 17: Tooth after removal of the caries and sealing of the chamber with flowable composite and dental dam.

Fig. 18: First removed piece of the broken file.

Fig. 19: Second removed piece of the broken file.

Fig. 20: Intra-op radiograph confirming lack of bypass and of patency.

Fig. 21: Pulp chamber after the irrigation protocol.

Fig. 22: Pulp chamber after obturation.

Fig. 23: Post-op radiograph. Puff of the sealer visible.

Fig. 24: CBCT scan at the six-month follow-up.

Fig. 25: CBCT scan at the 12-month follow-up.

Case 3

The patient was referred to the office for root canal retreatment of three teeth before prosthodontic treatment. One of these teeth was the mandibular left first molar. The CBCT scan revealed two radiolucent spaces around both roots (Fig. 26). Moreover, the periapical radiograph showed a broken file in the mesiobuccal canal (Fig. 27). After administering anaesthesia and placing a dental dam, the old restorations were removed, a temporary composite build-up was performed, and the tooth was sealed with flowable dental dam (Figs. 28 & 29). The old gutta-percha cones were removed from all the canals (Fig. 30).

Fig. 24: CBCT scan at the six-month follow-up.

Fig. 25: CBCT scan at the 12-month follow-up.

Fig. 26: Pre-op CBCT scan. Two apical lesions visible.

Fig. 27: Pre-op radiograph. Broken files visible.

Fig. 28: Treated tooth after dental dam isolation.

Fig. 29: Tooth after removal of the caries and sealing of the chamber with flowable composite and dental dam.

Fig. 30: Removal of the gutta-percha.

Fig. 31: Apparent over-instrumentation of the root canal orifice, probably performed with ultrasonics during a previous attempt at broken file removal.

Fig. 32: Root canal orifice sealed with flowable composite.

Fig. 33: View of the two broken files together in the mesiobuccal canal.

Fig. 34: One of the retrieved file pieces in the lasso tool.

After the removal of the gutta-percha and cleaning of the root canals, it was apparent that a large amount of the dentine had been removed from the orifice of the mesiobuccal canal (Fig. 31). Most probably, this had occurred during an attempt at removing the broken file in the previous treatment. Fortunately, there were no visible signs of perforation in the orifice. The damaged wall was sealed with composite resin (Fig. 32). Irrigation of the mesiobuccal canal with the AutoSWEEPS mode and sodium hypochlorite and inspection under 16× magnification revealed two pieces of the broken instruments (Fig. 33), complicating treatment. The tips of both files were visible, but both were also jammed. An attempt at removal with an ultrasonic file was ineffective, so the flat SWEEPS 300/20 fibre tip was used with the AutoSWEEPS mode at a power of 1.2 W. After a few minutes of irrigation with sodium hypochlorite and EDTA, both file pieces started to move a little, indicating that both were removable. Both pieces were retrieved with a lasso loop tool (BTR Pen, CERKAMED; Fig. 34). A periapical radiograph was performed to confirm that there were no more broken file pieces (Fig. 35).

After the file retrieval, all the canals were shaped with rotary files, and the final irrigation protocol was performed with the SSP (super-short pulse) mode. After the irrigation protocol, irrigant flow between the mesiobuccal and mesiolingual canals was rapid. The canals were dried. We could clearly see that the orifices of the mesial canals were of very similar ISO size, indicating that the file retrieval had been very conservative (Fig. 36). The canals were filled with an epoxy resin sealer and gutta-percha with the continuous wave technique (Fig. 37). A distally shifted periapical radiograph was performed, and on it, we could see in the mesial root that two parts of the isthmus had been filled with the sealer (Fig. 38). The tooth was restored with a fibre post and referred to the prosthodontist for indirect restoration.

After 12 months, a CBCT scan was performed (Fig. 39). The image found no signs of inflammation in the periapical area, and the tooth was asymptomatic.

Fig. 35: Intra-op radiograph. All pieces of the broken files had been removed.

Fig. 36: Pulp chamber after the irrigation protocol.

Fig. 37: Pulp chamber after obturation.

Fig. 38: Post-op radiograph.

Figs. 39a & b: CBCT scan at the 12-month follow-up.

Fig. 39b

Conclusion

Incorporating the Er:YAG laser into challenging endodontic treatments gives clinicians new possibilities, allowing them to achieve more effective, predictable and conservative treatment in many cases. In some cases, we can loosen the file without using ultrasonic tips, allowing us to be more conservative. Moreover, thanks to the much more effective reduction of accumulated hard-tissue debris, we can clean the space around the broken file to avoid removing the file (for example, if the file broke behind the curvature) and still have successful treatments with less risk of creating perforations in the classic approach to file retrieval.

Editorial note:

This article was published in roots—international magazine of endodontics vol. 19, issue 2/2023. A complete list of references can be found here.