|Year : 2022 | Volume
| Issue : 1 | Page : 59-62
Retrieval of overextending separated endodontic instrument: A review of methods and case report
Saaid Al Shehadat1, Mohamed El-Kishawi1, Renira Nisha Lobo1, Priyanka Jain2
1 Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, Sharjah, United Arab Emirates
2 Department of Endodontics, National University College of Dentist, Metro Manila, Philippines
|Date of Submission||24-Aug-2021|
|Date of Decision||08-Dec-2021|
|Date of Acceptance||10-Dec-2021|
|Date of Web Publication||19-Jan-2022|
Saaid Al Shehadat
Department of Preventive and Restorative Dentistry, College of Dental Medicine, University of Sharjah, P.O. Box: 27272, Sharjah.
United Arab Emirates
Source of Support: None, Conflict of Interest: None
Instrument separation during root canal treatment is one of the most unpleasant mishaps. Several techniques have been described to retrieve the separated instruments; however, they generally require specific tools that are not always available at dental clinics. This case report aims at presenting a simple alternative technique for the removal of root canal instruments separated during endodontic treatment. Endodontic retreatment was indicated for a maxillary lateral incisor of a 19-year-old patient. The radiographic examinations revealed the presence of a separated (fractured) instrument beyond the apical part of the canal. Retreatment was initiated by removing the obturated materials. After several unsuccessful attempts to retrieve the broken fragment, a hypodermic needle with chemically self-cure acrylic resin was used under an endodontic microscope to remove the separated fragment successfully. The retrieval technique used in this case was safe, simple, and low cost.
Keywords: Broken file, endodontic microscope, root canal preparation, separated instrument
|How to cite this article:|
Al Shehadat S, El-Kishawi M, Nisha Lobo R, Jain P. Retrieval of overextending separated endodontic instrument: A review of methods and case report. Adv Biomed Health Sci 2022;1:59-62
|How to cite this URL:|
Al Shehadat S, El-Kishawi M, Nisha Lobo R, Jain P. Retrieval of overextending separated endodontic instrument: A review of methods and case report. Adv Biomed Health Sci [serial online] 2022 [cited 2022 Aug 11];1:59-62. Available from: http://www.abhsjournal.net/text.asp?2022/1/1/59/335724
| Background|| |
The unfortunate separation (fracture) of instruments in the root canal increases the risk of failure of endodontic treatment, because it reduces the effectiveness of root canal disinfection, hinders root canal obturation, and compromises long-term prognosis . Failure of stainless steel instruments is usually caused by excessive torque, whereas NiTi rotary files usually separate due to torsional stress and cyclic loading . In addition, separation of an instrument can occur due to the operator’s carelessness or lack of skill and experience . The incidence of separated instruments (SI) was reported to be 0.39% to 5% among cases of endodontic retreatment . Retained SI tends to produce corrosion products in the root canal and, thus, can lead to the failure of the treatment .
Available options to manage SI in the root canal include leaving (retaining), bypassing, or retrieving the fractured fragment. The clinician should determine the best option based on a careful and detailed evaluation of complicating factors, including the complex anatomy of the root canal system, instruments available for the removal procedure, the localization, size, and position of the SI, and lastly his/her experience and expertise. Although SI may not cause treatment failure in some cases, it should be retrieved because it can be a source of the patient’s anxiety and may be accused as the source of any future problem that the patient may encounter . This option may be more suitable for SI located in the coronal and middle parts of the root canal system. Retaining the fragment should be the last option to consider, as the retained fragment may compromise chemo-mechanical cleaning and the following root canal filling and negatively affect the long-term prognosis . The clinician may be compelled for this option for instruments separated in the apical part of the root canal, particularly beyond the curvatures, where it would be risky to proceed for retrieving or bypassing the SI. In such cases, thorough irrigation and thermos-plasticized obturation techniques are highly recommended to improve cleaning and sealing of the apical part. From clinical experience, using bioceramic sealers is a superior option because of their excellent flow and ability to leak around the SI.
Different methods have been suggested to retrieve instruments separated in root canals. Historically, some chemicals, including sulfuric acid and hydrochloric acid, are used to dissolve the metal fragment . However, this method does not survive long mainly because of safety issues. Hand endodontic files have been used for a long time to remove SI from root canals. The technique includes bypassing the SI first by using a small K-file and gradually moving to bigger sizes before trying to retrieve it by H-file or double K-files that can be placed together in the canal to shackle the SI and withdraw it out. However, the success of this technique is not warranted due to the risk of separating more files or creating perforation in the canal wall. With the introduction of operative microscopes to dental clinics, new techniques become available, and the removal of SI becomes more predictable. Recent techniques depend mainly on the exposure of the tip of the SI, and it can be loosened by removing some dentin around it by using endodontic ultrasonic tips. Short fragments in straight canals may be retrieved by ultrasonic activation only. However, activation to retrieve long fragments or instruments separated in curved canals is not recommended, because it results in the excessive removal of dentin. In such cases, the usage of additional devices is needed to capture the tip of the fragment and withdraw it out of the canal.
Some tools used to retrieve a loose SI are simple and usually available in every clinic. An example of these simple techniques is the usage of softened gutta percha (GP) point . In this technique, the apical 2–3 mm of a suitable size of GP is softened by using dissolvent chemicals, such as chloroform, inserted into the canal over the SI and allowed to harden for 3 min. The GP is then rotated carefully in the clockwise and counterclockwise direction before being pulled out of the canal with the SI. A barbed broach with a piece of cotton around can be used to remove loose SI . A more practical tool is the hypodermic surgical needle. In this technique, the needle is shortened by removing the beveled tip and placed in the canal so that the tip of the SI is placed inside the needle’s lumen [10,11] A suitable size of K-file or H-file is inserted in the needle to tighten the SI. The whole set, including the SI, is then withdrawn carefully from the canal. The needle size should be selected carefully to allow its lumen to encase the coronal tip of the SI precisely. Using a cyanoacrylate glue, suitable dental cement, or acrylic resin to fill the needle lumen presents an alternative option.
Many of the advanced tools, known as microtube extractors or hollow tube-based extractor systems, use the same principle of the hypodermic needle technique in terms of engaging the intracanal SI mechanically . Some of these devices are Masserann kit (Micro-Méga, Besançon, France); removal system iRS (Dentsply Tulsa Dental; Tulsa, Oklahoma); File removal system (Dentisply Dental Specialties, Tulsa, Oklahoma), Endo RescueTM (Komet/Brasseler, Savannah, Georgia); Ruddle Post Removal System (SybronEndo; Orange, California); and Meitrac systems (Hager and Meisinger, Neuss, Germany). However, all these devices have some limitations, including the need for excessive removal of dentin around the SI, the risk of ledging or perforation, poor performance in narrow and curved roots, and possible extrusion of the SI through the apex . A new generation of micro-extractor system was introduced recently. Zumax broken instrument removal kit (Zumax Medical Co., Ltd., Jiangsu, China) has different sizes of more practical hollow tubes that can be attached to a handle for more comfortable manipulation. Finally, mechanical engaging of the intracanal SI can be performed by using loops present in the Terauchi file retrieval kit (TFRK, Dental Engineering Laboratories, Santa Barbara, California) and sistemul BTR Pen (Broken Tool Remover Pen–Cerkamed). However, from clinical experience, the retrieval of long SI, unloose SI, or SI located in a curved part of the canal remains challenging.
| Case report|| |
A 19-year-old healthy young female patient came to the University Dental Hospital, Sharjah, to have her maxillary lateral incisor restored. The clinical examination revealed that the tooth had a fractured crown with evidence of a previous RCT, which was exposed to the oral environment at the moment of the examination. The patient was asymptomatic, and the tooth was not tender to percussion or palpation. The intraoral periapical X ray revealed the presence of a separated long file that extended beyond the apex [Figure 1]A. A periapical radiolucency was observed on the x-ray with evidence of external resorption of the root. The patient was medically fit for endodontic treatment.
|Figure 1: Retrieval of the overextended separated instrument. (A) Initial periapical radiograph showing the fragment beyond the apex of the tooth (arrow). (B) Periapical radiograph confirming the attachment of the fragment to the syringe needle. (C) Photograph of the syringe needle and the fractured instrument removed from the root canal. (D) Calcium hydroxide packed into the root canal after the successful removal of the fractured instrument. (E) Final partial root filling. (F) 1-year follow-up|
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Nonsurgical endodontic retreatment was indicated and initiated. The case was managed under magnification using dental microscope (S7/OPMI PROergo; Carl Zeiss, Oberkochen, Germany). The gutta-percha was first removed by using an ultrasonic tip (ET20, Satelec, Acteon, France). The separated file was recognized and became loose at this stage, but it was not retrieved by ultrasonic activation.
The tip of a syringe needle (gauge 21) was rounded and tried into the canal. The beveled part of the needle was cut to allow for easy attachment of the needle to the fragment. The size of the needle was found suitable to fit over the tip of the separated fragment. When tactile sensation of the attachment was felt, a radiograph was taken to confirm the attachment. The needle was then filled with chemical self-cure acrylic resin (Vertex, Dentimex Zeist, Holland) and immediately reinserted in the canal [Figure 1B]. After polymerization for 6 min, the needle was rotated anticlockwise, resulting in successful retrieval of the separated file [Figure 1C].
Actual working length was determined, and the root canal was irrigated and cleaned properly. The irrigant used was 3% sodium hypochlorite. Final irrigation was achieved by 17% EDTA under ultrasonic activation for 1 min and finalized with 3% sodium hypochlorite. Saline was used between different irrigants without activation. Calcium hydroxide dressing was placed into the canal, and the composite crown was considered as temporary restoration [Figure 1D]. Final partial root filling was achieved after 1 month following the worm vertical compaction technique [WVC, [Figure 1E]]. The case was referred to the prosthodontist for the final permanent restoration. The 1-year follow up revealed the complete healing of the periapical lesion [Figure 1F].
| Discussion|| |
The causes of separation of endodontic instrument are complex and multifactorial . Overall, such mishaps are a result of movements applied incorrectly on instruments or using already damaged instruments, thereby increasing the chance of separation by cyclic fatigue or torsion stress . The cyclic fatigue of a file is related to the degree of flexure that the file undergoes in a curved root canal . Larger curvature degree results in greater cyclic fatigue and higher risk of file separation. Separation due to torsion occurs when the tip of the file is stuck in the canal while the handpiece keeps rotating. In such a case, the elastic limit of the file alloy is exceeded and the file is separated .
Careful consideration should be taken before choosing to remove the SI from the root canal. The success rate should overweigh the complications . The SI itself may not cause failure, but it may prevent the sufficient preparation and disinfection of the canal system and compromise the long-term success of the treatment . Attempts to remove SI may end with ledge formation, perforation, or over preparation and transportation of the root canal. Hence, the clinician should carefully evaluate the options of whether to remove, bypass, or leave the fragment in the canal.
Several techniques can be used to remove an SI from the root canals. Some of them are simple, safe, and cheap, whereas others are more complicated and expensive and may consume a significant amount of root dentine . The removal of an SI by using a syringe needle with acrylic resin is a simple low-cost technique. It uses routine materials that are usually available in every dental clinic. Further, the technique is not time-consuming because the setting time of the resin is a few minutes. One of the main advantages of this technique is the safety of the method. It performs minimal dentinal removal, leading to less weakening of the tooth and less risk of subsequent fracture compared with other techniques . However, this technique does need an individual with good skills to attach the needle to the exposed coronal part of the fragment under a microscope.
A similar simple hollow tube-based extractor technique with different modifications was used to retrieve SIs [10,11]. A needle was used with K-files to shackle the SI and retrieve it out of the root canal. The needle-K file technique is simple but has the disadvantage of finding the suitable sizes of the needle and K-file. Therefore, more time and attempts might be required to retrieve the SI successfully. However, the clinician needs to be aware of such other available techniques and tools. Good knowledge of the root canal anatomy and the accurate direction of root curvatures, if exist, are a must to reduce complications during SI removal  [Table 1]. In conclusion, the nonsurgical retrieval of a separated fragment beyond the apex is still possible if the instrument inside the root canal has sufficient length. The simple and always available hypodermic needle can be used under magnification to retrieve broken fragments from the root canal.
|Table 1: Recommended guidelines for the retrieval of a separated instrument|
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The retrieval of a separate instrument technique described in this article needs good skill to remove dentine around the separated fragment by using an ultrasonic tip under a dental microscope.
SA conceived the research concept, developed research design, and performed field work; ME performed field work and data analysis; RL performed field work and developed research design; and PJ performed field work and data analysis. All the authors reviewed and approved the final draft of the article. All the authors are responsible for the contents and integrity of this article.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
Data availability statement
All data generated or analyzed during this study are included in this published article.
An informed consent was obtained from the patient to publish this report in the journal.
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