Abstract

The fracture of an endodontic instrument is an obstacle in completion of a routine successful pulp space therapy. Ni-Ti instruments corrode when in contact with sodium hypochlorite which leads to their deterioration and ultimately fracture during use. Removal of separated instrument from root canal is often a very difficult procedure. This procedure is more complicated when the instrument separated is closer to the mandibular canal. A case is presented in which a separated hand instrument was retrieved from the mesio buccal of a second molar approximating the mandibular canal root by replantation.

Keywords:broken instrument, instrument retrieval mandibular canal, replantation

How to cite this article:Shenoy A, Mandava P, Bolla N, Vemuri S. A novel technique for removal of broken instrument from root canal in mandibular second molar. Indian J Dent Res 2014;25:107-10

How to cite this URL:Shenoy A, Mandava P, Bolla N, Vemuri S. A novel technique for removal of broken instrument from root canal in mandibular second molar. Indian J Dent Res [serial online] 2014 [cited2015 Jan 10];25:107-10. Available from:http://www.ijdr.in/text.asp?2014/25/1/107/131157

Every clinician who has performed Endodontic therapy has experienced a variety of emotions ranging from thrill to unpleasant upset situations, while treating patients. Clinicians may encounter a variety of unwanted procedural accidents and obstacles during a routine endodontic therapy. One of these procedural problems is intracanal instrument fracture. Fractured root canal instruments may include endodontic files, Gates Glidden burs, finger spreaders, and paste fillers. The potential difficulty in removing instrument fragments and a perceived adverse prognostic effect of this procedural complication is a main reason for resistance to adoption of this innovation.[1]Today separated instruments can usually be removed due to technological advancements in vision, ultrasonic instrumentation, and micro tube delivery methods. Various techniques to remove these instruments from root canal have been explained in dental literature,

a) Use of Stieglitz pliers to remove the silver points.[2]

b) Grossman has suggested that chloroform or xylol can be used to soften the gutta-percha which is then easily removed with a file or a barbed broach.[3]

c) Riog Green demonstrated the use of a simple device consisting of a disposable 25-gauze dental needle, a segment of thin steel wire and a small mosquito hemostat to remove silver cones from the root canals.

d) Fors and Berg described a technique that required removal of internal root structure before the instrument is removed.

e) Williams and Vjirndal described the Masserann technique to remove the fractured post.[4]

f) Ultrasonic scaler has been used to remove solid objects from the root canal.

g) Meidinger and Kahes successfully used the Cavi-Endo ultrasonic instruments to remove a broken bur tip and amalgam particles from the intracanal spaces.[5]

h) Taintor et al. described various methods for the removal of silver cones.

i) Micro tube removal systems like Lasso and Anchor, Tube and Glue, Tap and tread, Endo extractor removal system.[6]

With a more frequent use of nickel titanium rotary files in Endodontics, the incidence of file separation within the canals has increased. When the file is broken at the apex, the microscope cannot be of help. If the file breaks within the coronal half of the canal, then the microscope is essential to guide the clinician to retrieve the broken files. In this manner, the broken file can be removed while minimizing the damage to the surrounding dentine.

Case Report

A 37 year old female patient came to the Department of Conservative Dentistry and Endodontics with the chief complaint of pain in lower left back region. Pre-operative radiograph[Figure 1]revealed radiolucency involving enamel, dentine and pulp with periodontal widening and radiolucency in mandibular second molar region. Conventional pulp space therapy was proposed. Access cavity was prepared and during the course of biomechanical preparation, a 25 size K-file got separated at the apical region of the mesiobuccal root canal. On radiographic examination, the separated instrument was protruding 3 mm beyond the apex approximating the mandibular canal[Figure 2].The patient was informed about the instrument inside the canal and ill-effects of keeping it untouched since it was protruding beyond the root apex. She was also explained the different techniques with which an attempt can be made to remove the instrument. The advantages and disadvantages of various techniques were explained to the patient in detail. The patient declined for Periapical surgery and other options however she gave her consent for intentional replantation. Cleaning and shaping was completed for distal and mesiolingual canals. Both distal and mesiolingual canals were obturated. In the pulp chamber, a cotton pellet was placed and was restored with composite. Orthodontic bands were prepared. Under aseptic conditions, atraumatic extraction was done and the entrance restoration was removed[Figure 3]. Extra orally, the separated instrument was retrieved. It measured around 7 mm[Figure 4]. The mesiobuccal canal was cleaned, shaped, and obturated[Figure 5]. The tooth was re-implanted. For the stabilization of this re-implanted tooth, orthodontic bands were placed on both first and second molars and the bands were cemented with Zinc Phosphate cement[Figure 6]. Entrance filling was given with Glass Ionomer Cement. Post-operative radiograph was taken to confirm the position of tooth[Figure 7]and[Figure 8]. Band was removed after 4 weeks and radiograph taken for the evaluation of Periapical region[Figure 9]. Periodic evaluation was done after 1 month[Figure 10], 3 months[Figure 11], and one year[Figure 12]and[Figure 13]for further evaluation and there was reduced Periapical radiolucency.Figure 1: Preoperative radiograph

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Figure 2: Broken instrument near to the mandibular canal

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Figure 3: After extraction

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Figure 4: Measured broken instrument of 7 mm

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Figure 5: After obturation

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Figure 6: After separators were placed

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Figure 7: Extra coronal splinting with orthodontic wires were prepared

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Figure 8: Post operative Radiograph

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Figure 9: Four weeks after Band removal

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Figure 10: One month follow-up Radiograph

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Figure 11: Three months follow-up Radiograph

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Figure 12: One year follow-up radiograph

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Figure 13: One year clinical radiograph

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Discussion

The factors that favor the removal of broken instruments from the canal should be identified and appreciated. Non-surgical management of separated instrument will be influenced by the diameter, length, and position of the instrument within a canal. The safe removal of a separated instrument is further guided by the anatomy, which includes the length, diameter, canal curvature, and additionally limited by root morphology, which includes the thickness of dentin and the depth of external concavities. An instrument can be usually removed if one-third of its overall length is exposed. Instruments that lie in the straightaway portions of the canal can many a times be removed. At times an instrument may be separated apical to the curvature of the canal. In such cases, a safe access to the site of separation may not be achieved. Then the retrieval of the separated instrument is usually not possible and surgery or extraction will be needed at times in presence of adverse signs and symptoms. The type of material causing an obstruction is another important factor to be considered. Stainless steel files do not fracture further during removal process and they have a tendency for easier removal.[7]Nickel titanium separated instruments may break again, albeit deeper within the canal, due to heat build-up during the use of ultrasonics.[8]It is also important to know whether the file was rotating clockwise or anticlockwise just before separation as this factor will influence the proper ultrasonic removal technique. Another factor that helps in successful instrument removal is combining the best of the presently developed and proven technologies. Traditionally, retrieving separated instruments posed formidable challenges. One technique that has been followed is the use of small files in effort to either remove, or at least bypass, the separated instrument. The retrieval techniques have evolved over the years but were often ineffective because of restricted space and/or limited vision. Often successful separated instrument retrieval predisposed the tooth to fracture and thus loss of tooth and this is due to overzealous canal enlargement. The prognosis of a tooth can be seriously compromised if the efforts to remove a separated instrument lead to iatrogenic events, such as a ledged canal or root perforation. When retrieval efforts of the separated instruments are not successful, biomechanical preparation and obturation procedures are compromised and the ultimate prognosis will be in doubt. In such situations it will be better to do an intentional replantation by stabilizing the tooth in appropriate position for better outcome of the treatment.[9]Splinting procedures should go along with periodic recall, which will help in achieving better stabilization and biological integrity towards root canal treatment.[1]

Cone beam computed tomography [CBCT] has been used in endodontics for an effective evaluation of the root canal morphology along with the diagnosis of endodontic pathology, assessing root and alveolar fractures, analysis of re-absorptive lesions, identification of non-endodontic pathology, and pre-surgical assessment before root end surgery.[10],[11]The cone beam computed tomography, if available can be of use to know the proximity of the instrument to the mandibular canal. However, this equipment is not available everywhere.

There are some advantages in performing an intentional replantation when compared to the Periapical surgery or when surgery is refused. Replantation is less invasive and less time consuming. If the case selection is proper the replantation can be simple and straightforward. The chance for damaging the nerve is also very less here. Many authors has advised that replantation should be considered as a last option after all other options fail or are likely to fail.[12]Since the separated instrument was inaccessible through non surgical means an intentional replantation was considered in our case report. Some studies have shown that the average time of retention after replantation is 3-5 years. The main reason for failure after replantation is due to replacement resorption. This is directly related to the amount of time that the tooth was out of the mouth during the procedure and before replantation.[12]If the extraoral time is very brief and there is very little damage to the cementum or periodontal ligament during extraction, then the prognosis is much better for the reimplanted tooth.[13]As mentioned before, in our case report, an atraumatic restoration was done and the tooth was replanted within a very little time and was splinted.

Conclusion

Prevention is the best antidote for a separated file in the canal. Adhering to proven concepts, combining the best strategies and making use of safe techniques during root canal preparation procedures will virtually eliminate the separated instrument procedural accident. Separation of instrument can be prevented if the instruments used for negotiating and cleaning and shaping the root canal are disposed and not reused. Discarding all instruments after the completion of each endodontic case will reduce breakage, lost clinical time, and upsets caused by procedural accidents. However, on occasion, an instrument might break and in spite of the best existing technologies and techniques, the retrieval may not be successful. In these instances, and in the presence of clinical symptoms and/or radiographic pathology, surgery or extraction may be the best treatment option.

References

1.Parashos P, Messer HH. Rotary NiTi instrument fracture and its consequences. J Endod 2006; 32:1031-43.

2.Schulz J, Gutterman JR, Cohen S, Burns RC. Pathways of Pulp. Non surgical endodontic treatment. 10thed: Mosby; 2010. p. 890-950.

3.Chandra BS, Krishna VG Grossman's Endodontic Practice. Procedural errors: prevention and management. 12thed: Wolters Kluwer and Lippincott Williams and Wilkins, India, 2010. p. 469-93.

4.Pai AR, Kamath MP, Basnet P. Retrieval of a separated file using Masserann technique: A case report. Kathmandu Univ Med J (KUMJ) 2006;4:238-42.

5.Plotino G, Pameijer CH, Grande NM, Somma F. Ultrasonics in endodontics: A review of the literature J Endod 2007;33:81-95.

6.Roydent. Endo extractor system. For removal of silver points and separated endodontic instruments, 11 Jan 2012 Available from: http://www. Roydent.com

7.Weine FS. Endodontic Therapy: Endodontic Emergency Treatment. 5thed. Mosby-year book, Inc 1997. p. 203-30.

8.Lindhe J, Nyman S. The role of occlusion in periodontal disease and the biological rationale for splinting in treatment of periodontitis Oral Sci Rev 1977;10:11-43.

9.Amsterdam M, Fox L. Provisional splinting - principles and techniques. Dent Clin North Am 1959;3:73-99.

10.Nair MK, Nair UP. Digital and advanced imaging in endodontics: A review. J Endod 2007 [33]1-6.

11.Matherne RP, Angelopoulos C, Kulild JC, Tira D. Use of cone-beam computed tomography to identify root canal systems in vitro. J Endod 2008;34:87-9.

12.Benenati FW. Intentional replantation of a mandibular second molar with long-term follow-up: Report of a case. Dent Traumatol 2003;19:233-6.

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13.Peer M. Intentional replantation-a last resort treatment or a conventional treatment procedure? Nine case reports. Dent Traumatol 2004;20:48-55.

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Correspondence Address:Amarnath ShenoyDepartment of Conservative Dentistry and Endodontics, Yenepoya Dental College, MangaloreIndia