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CASE REPORT
Year : 2021  |  Volume : 11  |  Issue : 1  |  Page : 111-115

Combined surgical and nonsurgical endodontic therapy for the retreatment of a root canal with a broken round bur in the apical third: A case report with a 4-year follow-up


Department of Restorative Dental Science, College of Dentistry, King Saud University, Riyadh, Kingdom of Saudi Arabia

Date of Submission28-May-2020
Date of Decision02-Jul-2020
Date of Acceptance16-Jul-2020
Date of Web Publication09-Jan-2021

Correspondence Address:
Dr. Sara Abdulrahman Alsubait
Department of Restorative Dental Science, College of Dentistry, King Saud University, P.O. Box 85676, Riyadh 11612
Kingdom of Saudi Arabia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/sej.sej_131_20

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  Abstract 


Management of endodontic lesions in previously treated teeth might be challenging due to the presence of procedural mishaps such as metallic objects that have been broken accidently by the previous treating dentist. A 36-year-old female complaining of pain with biting was referred for endodontic retreatment of her maxillary left central incisor. The involved tooth was sensitive to percussion, and the periapical radiographic examination revealed the presence of an apical radiolucency, a lateral radiolucency, and a separated round bur in the apical third. Cone-beam computed tomographic imaging was performed to provide a detailed assessment of the tooth and the surrounding structures. The tooth was diagnosed as previously treated with symptomatic apical periodontitis. Root canal retreatment was completed using a combined surgical and nonsurgical approach under an operating microscope. At 1-year follow-up, the patient was asymptomatic, and the two-dimensional radiographic examination revealed complete healing and remained so for the 4 years of follow-up. The presence of a broken bur in a previously filled root canal is unusual. Endodontic management of such cases requires careful evaluation and good clinical management.

Keywords: Cone-beam computed tomography, dental bur, EndoSequence BC putty, microsurgery, root canal retreatment


How to cite this article:
Alsubait SA. Combined surgical and nonsurgical endodontic therapy for the retreatment of a root canal with a broken round bur in the apical third: A case report with a 4-year follow-up. Saudi Endod J 2021;11:111-5

How to cite this URL:
Alsubait SA. Combined surgical and nonsurgical endodontic therapy for the retreatment of a root canal with a broken round bur in the apical third: A case report with a 4-year follow-up. Saudi Endod J [serial online] 2021 [cited 2021 Jan 19];11:111-5. Available from: https://www.saudiendodj.com/text.asp?2021/11/1/111/306599




  Introduction Top


The main objective of conventional root canal therapy is to prevent and/or eliminate apical periodontitis and to resolve patient symptoms.[1] Despite the high degree of success following initial root canal treatment, failure can occur in 17% of cases.[2] In such cases, nonsurgical retreatment is generally indicated if the tooth is restorable and the canals are accessible. The goal of root canal retreatment is to regain access to the apical foramen by complete removal of preexisting filling material to achieve complete disinfection of the root canal system.[3] However, in some cases, the canal can be blocked by metallic objects that have been broken accidently by the previous treating dentist, such as separated instruments[4],[5] and dental burs.[6],[7] A retained metallic obstruction may have a negative impact on the prognosis by preventing thorough cleaning and shaping of the root canal.[8] Management of separated fragments can be addressed with surgical or nonsurgical endodontic treatment.[9] This case presents the successful retreatment of a root canal with a broken round bur in the apical third using a combined surgical and nonsurgical approach.


  Case Report Top


A 36-year-old female was referred to the department of endodontics for management of her maxillary left central incisor (#21). The patient presented with a noncontributory medical history and a chief complaint of pain with biting for the last year. The dental history indicated that she had undergone root canal treatment 3 years ago in a private dental clinic. Clinical examination revealed that the tooth was sensitive to percussion. The tooth had no mobility, and the periodontal probing was within normal limits (<3 mm). The tooth had a defective Class IV composite restoration [Figure 1]a. Radiographic examination revealed a radiopaque root canal filling material in the coronal and middle thirds and an approximately 5 mm metallic fragment that indicated a separated round bur in the apical third. Two radiolucent areas were detected in the periapical region and lateral to the root [Figure 1]b. According to the clinical and radiographic examination, a diagnosis was made of previously treated with symptomatic apical periodontitis. Cone-beam computed tomographic (CBCT) imaging (Promax 3D Max, Planmeca, Roselle, IL, USA) was planned to provide a three-dimensional evaluation and to assess the possible presence of apical perforation as a result of the broken bur. Examination of the CBCT images showed the presence of an area of low density associated with the apex of #21 that does not cause any perforations in buccal or palatal cortical plates. The broken instrument did not seem to perforate the root. Another low-density area is seen in the mesial surface of the root located more toward the buccal surface [Figure 1]c and [Figure 1]d.
Figure 1: (a) Preoperative clinical view. (b) A preoperative radiograph of the maxillary left central incisor. (c) Preoperative cone-beam computed tomographic imaging showed a low-density area associated with the root apex and another low-density area at the mesial root surface in the coronal slice. (d) In the sagittal slice, there is no evidence of any perforations in the buccal or palatal cortical plates

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After discussing the treatment options with the patient, a decision was made to start nonsurgical endodontic retreatment. However, a surgical approach might be required for the retrieval of the broken bur. During the first appointment, after local anesthesia and rubber dam isolation, the defective permanent restoration was removed, and access was obtained under an operating microscope (OPMI pico, Carl Zeiss, Thornwood, NY, USA). Gutta-percha was removed using ProFile #25/06 (Dentsply Maillefer, Ballaigues, Switzerland) at 500 revolutions per minute (rpm). The fragment was completely bypassed with a size 15 K-file (Dentsply Maillefer, Ballaigues, Switzerland), and the working length was confirmed with a radiograph [Figure 2]a. The glide path was established by hand filing with up to a size 25 K-file. An ultrasonic tip (Satelec Acteon Group, Merignac, France) was placed inside the canal and activated without coolant for 1 min, and then the canal was irrigated with 2.5% sodium hypochlorite (NaOCl) to cool the operating field and flush the debris out. However, several removal attempts with ultrasonic vibration were unsuccessful. Instrumentation was completed with ProTaper Gold rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to F3 file at 300 rpm with continuous irrigation with 2.5% NaOCl. The fragment could not be loosened from the root canal wall even with the repeated use of ultrasonic vibration. Therefore, a decision was made to include a surgical approach to push the fragment from the apex to the access cavity.
Figure 2: (a) Working length determination after bypassing the separated metallic fragment. (b) Radiograph taken at the end of the 1st visit. (c) Final radiograph after backfilling the canal with gutta-percha. (d) A 6-month follow-up radiograph. (e) Complete healing was evident at the 1-year follow-up visit

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In the same session, after the removal of the rubber dam, an intrasulcular incision with a single vertical releasing incision was made with a #15 scalpel blade, and a labial full-thickness flap was reflected. Osteotomy was performed with a round tungsten carbide bur under constant copious irrigation with sterile saline followed by root-end resection with a Lindeman carbide bur (Brasseler, Savanna, GA, USA). The periapical soft-tissue lesion was curetted, collected, and sent to the histopathology department for analysis. For fragment removal, a high-volume suction tip was placed at the coronal access cavity, and a microsurgical plugger (Hu-Friedy Mfg Co., Chicago, IL, USA) was used to push the separated instrument from the root tip toward the access cavity. Then, methylene blue dye was applied to the resected root surface to identify the periodontal ligament, root outline, and canal. Root-end preparation was performed using ultrasonic tips (ProUltra surgical tips, Dentsply, Oklahoma) mounted on an ultrasonic device (P5 Newtron; Satelec, Acteon Group, Merignac, France). To facilitate the placement and condensation of root-end filling material, a gutta-percha cone was placed through the coronal access cavity 3 mm short of the root end. EndoSequence BC Root Repair Material Fast Set Putty (Brassler USA, Savannah, GA, USA) was inserted into the prepared root end. The flap was repositioned after incising the periosteum at the base of the flap to obtain tension-free closure and sutured with multiple interrupted 4-0 Vicryl sutures (Ethicon, Somerville, NJ, USA). Gutta-percha was removed from the root canal. A resin-modified glass ionomer (GC Fuji II LC; GC America Inc., Alsip, IL, USA) was used to replace the missing tooth structure, and the access cavity was closed with a temporary restorative material (Coltosol F, Coltène, Altstätten, Switzerland). A postoperative radiograph was taken [Figure 2]b. The patient was advised not to rinse for 24 h, followed by rinsing twice daily with 0.2% chlorhexidine for 1 week. The patient was prescribed an oral analgesic (ibuprofen 400 mg, every 8 h for 3 days).

The patient returned 1 week after the initial visit for suture removal and to complete the endodontic retreatment. During the second appointment, the patient did not complain of any postoperative pain. After local anesthesia and rubber dam isolation, the temporary filling material was removed. The setting of the EndoSequence BC Putty was confirmed. The canal was irrigated copiously with 2.5% NaOCl. The irrigant was activated with a passive ultrasonic technique (Irrisafe; Satelec Acteon Group, Merignac, France). The smear layer was removed with 17% EDTA for 1 min followed by 2.5% NaOCl. After drying the canal with paper points (Dentsply Maillefer, Tulsa, Oklahoma, USA), it was obturated with injectable gutta-percha (Beta, B&L Biotech, USA) and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). The access opening was sealed with temporary restorative material, and a postoperative periapical radiograph was taken [Figure 2]c. The patient was referred to an operative specialist for the permanent restoration. A biopsy report described a periapical granuloma.

The patient was scheduled for posttreatment follow-up examinations at 6 months, 12 months, and 4 years. During the follow-up visits, the patient was completely asymptomatic, and the tooth was not sensitive to percussion, exhibited no mobility, and had normal probing depths. At the 6-month follow-up appointment, a radiograph showed evidence of osseous repair in the periapical and lateral radiolucent areas [Figure 2]d. At 12 months, the radiograph revealed complete healing in both radiolucent areas [Figure 2]e. The outcome was judged as healed after 1 year and remained so for the 4 years of follow-up [Figure 3]a and [Figure 3]b.
Figure 3: (a) A clinical photograph at the 4-year follow-up visit. (b) A 4-year recall periapical radiograph

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  Discussion Top


The incidence of bur breakage inside the root canal is quite low in the literature.[6],[7] In previously published case reports, the dental bur was fractured during access cavity preparation and was successfully removed from the canal using an orthograde approach.[6],[7] In the present case, the management of teeth with a previous filling material and a separated bur using both surgical and nonsurgical approaches was explained. The exact mode of separation in this case is not known. The bur might have been fractured during access cavity preparation and was pushed inside the canal while attempting removal, or it was caused by poor practice and was fractured inside the canal. The main limitation of intraoral periapical radiographs is that it is a two-dimensional image of a three-dimensional object.[10] To overcome this problem, CBCT was requested in the present case to generate three-dimensional images of tooth #21 and surrounding tissue for better preoperative assessment.

Separated instruments can be managed by orthograde or surgical approaches. Different techniques and devices can be used for the removal of separated instruments.[9] It has been reported that the use of ultrasonic vibration under a dental operating microscope is successful in 95% of cases.[11] In the present case, the fragment was successfully bypassed with hand files, and space was created to introduce ultrasonic tips aiming to dislodge it coronally. However, the retrieval efforts were unsuccessful. Cleaning and shaping was completed to the full working length, and the fragment was still resistant to removal. Failure of fragment removal attempts could be related to its length, diameter, and location.[9] The success of endodontic treatment is affected negatively by the presence of a preoperative periapical lesion.[12] It has been reported in a case–control study that cases with separated instruments and periapical lesions had an 11.7% lower success rate than those with separated instruments but without periapical lesions.[12] In addition, the separated metallic fragment appears like a dental bur on radiographic images. Dental bur corrosion and the corrosive effect of NaOCl on metallic instruments have been reported in the literature.[13],[14] Moreover, the decision of fragment removal was in accordance with the patient's preference. Due to the risk of root weakening or perforation that might result from the aggressive use of instrument retrieval devices,[15] the decision was made to remove the fragment by including a surgical intervention. Furthermore, it was decided to remove the fragment surgically before obturation because it would be easier to remove it through the access cavity due to the large taper and diameter of the fragment. After root-end resection and removal of the metallic fragment, two treatment options were available: either to place the retrofill material followed by wound closure or to complete the treatment after flap repositioning and suturing by orthograde apical plug placement. Since the placement and condensation of retrofill material could be controlled by the placement of a gutta-percha cone inside the canal, the former treatment option was selected.

Different materials have been used as root-end filling materials including Super EBA, mineral trioxide aggregate, and EndoSequence BC Putty.[16],[17] In the present case, EndoSequence BC Putty was selected because of its advantages in terms of biocompatibility and bioactivity.[18] It is available as a premixed moldable putty that allows easy placement in the retro-preparation. Furthermore, the success rate of endodontic microsurgery when EndoSequence BC putty is used as a root-end filling material has been reported to be 92%.[17] In this case, the benefit of combining microsurgical and orthograde retreatment therapies is to maintain the root strength while being able to remove the broken bur and to effectively disinfect and seal the infected canal.


  Conclusion Top


The presence of a broken bur in a previously filled root canal is rare and unusual. Endodontic management of such cases requires careful clinical and radiographic examination. In the present case, successful management was performed by the combined use of microsurgical and orthograde retreatment techniques.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published, and due efforts will be made to conceal her identity, but anonymity cannot be guaranteed.

Acknowledgments

The author would like to thank Dr. Alhanouf Alhabdan, assistant professor in the Department of Restorative Dental Science, for performing the coronal restoration of the case.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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2.
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Kanagasingam S, Lim CX, Yong CP, Mannocci F, Patel S. Diagnostic accuracy of periapical radiography and cone beam computed tomography in detecting apical periodontitis using histopathological findings as a reference standard. Int Endod J 2017;50:417-26.  Back to cited text no. 10
    
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Bapna MS, Mueller HJ. Corrosion of dental burs in sterilizing and disinfecting solutions. J Prosthet Dent 1988;59:503-11.  Back to cited text no. 13
    
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Eichner MA, Schoen DM, Goldman M, Kronman JH. Effect of protein and sodium hypochlorite on endodontic instruments. J Endod 1976;2:335-8.  Back to cited text no. 14
    
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Kohli MR, Berenji H, Setzer FC, Lee SM, Karabucak B. Outcome of Endodontic Surgery: A Meta-analysis of the Literature-Part 3: Comparison of Endodontic Microsurgical Techniques with 2 Different Root-end Filling Materials. J Endod 2018;44:923-31.  Back to cited text no. 16
    
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Chen I, Karabucak B, Wang C, Wang HG, Koyama E, Kohli MR, et al. Healing after root-end microsurgery by using mineral trioxide aggregate and a new calcium silicate-based bioceramic material as root-end filling materials in dogs. J Endod 2015;41:389-99.  Back to cited text no. 18
    


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  [Figure 1], [Figure 2], [Figure 3]



 

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