Management of a separated paste carrier in the mandibular central incisor

Sweta Rastogi; Kulvinder Singh Banga; Sarang Sharma; Dhirendra Srivastava

doi:10.4103/jdrr.jdrr_32_20

CASE REPORT

Year : 2020 | Volume : 7 | Issue : 3 | Page : 134-137

Management of a separated paste carrier in the mandibular central incisor

Sweta Rastogi¹, Kulvinder Singh Banga², Sarang Sharma¹, Dhirendra Srivastava³
¹ Department of Conservative Dentistry and Endodontics, ESIC Dental College and Hospital, Delhi, India
² Department of Conservative Dentistry and Endodontics, Nair Hospital Dental College, Mumbai, Maharashtra, India
³ Department of Oral and Maxillofacial Surgery, ESIC Dental College and Hospital, Delhi, India

Date of Submission	29-Apr-2020
Date of Decision	09-May-2020
Date of Acceptance	05-Nov-2020
Date of Web Publication	08-Oct-2020

Correspondence Address:
Sweta Rastogi
Department of Conservative Dentistry and Endodontics, ESIC Dental College and Hospital, Rohini, Delhi
India

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jdrr.jdrr_32_20

Abstract

Success and failure of root canal treatment are a debatable topic as it depends on various factors, including knowledge and expertise of the clinician as well as host responses that are subjective in nature. Knowing the canal anatomy to guide the instrument through it is as important as knowing the complications of guiding it through the canal. One such complication often encountered by clinicians is instrument separation. The protocols recommended to manage the complication include leaving the separated instrument in situ in the root canal, bypassing the fragment and incorporating it in the obturating material, removal from the root canal, and surgical management as the last resort. This case demonstrates the removal of a separated lentulo spiral from the root canal, including the use of magnification, which facilitates the treatment.

Keywords: Instrument separation, Lentulo spiral, Magnification, Masserann kit, Root canal

How to cite this article:
Rastogi S, Banga KS, Sharma S, Srivastava D. Management of a separated paste carrier in the mandibular central incisor. J Dent Res Rev 2020;7:134-7

How to cite this URL:
Rastogi S, Banga KS, Sharma S, Srivastava D. Management of a separated paste carrier in the mandibular central incisor. J Dent Res Rev [serial online] 2020 [cited 2023 Mar 29];7:134-7. Available from: https://www.jdrr.org/text.asp?2020/7/3/134/297521

Introduction

Instrument separation is an unfortunate event that creates anguish even in the best of clinicians as well as in the patients. The separated instrument acts as an impediment and can jeopardize the outcome of root canal treatment as it might obstruct access to the apical terminus of the tooth, thus preventing the adequate cleaning and shaping procedures as well as obturation of the root canal system.

The prevalence of separated instruments in the root canal system ranges from 0.5% to 5%, according to Iqbal et al.^[1] and from 2% to 6%, according to Kerekes and Tronstad.^[2] In reported literature, the frequency of separation of Ni-Ti instruments is remarkably more than that of stainless-steel instruments, which ranges from 1.3%–10% to 0.25–6%, respectively.^[1],[3],[4]

Although there is no standard protocol to be followed for managing a tooth that has undergone instrument separation, but the management is influenced by factors such as tooth factor, equipment and instrument factor, clinician factor, and patient factor.^[5]

Methods employed for retrieval of separated instrument range from the use of steiglitz forceps, micro-tube, or an injection needle used in combination with a Hedstrom file or an orthodontic wire,^[6] tube-like systems which include the Endo-Extractor system (Roydent Dental Products, USA), Masserann kit (Micro Mega, France), Instrument Removal System (San Diego Swiss, USA), Separated Instrument Removal System (Vista Dental Products, USA), Cancelier instrument and Mounce extractor (Sybron Endo, CA) to ultrasonic aided by Dental Operating Microscope, Laser (ND:YAG), and Electrolysis.^[6],[7]

Visualization of the separated instrument is highly important for deciding which retrieval system is to be used; hence, instrument retrieval should always be aided with magnification. This case exhibits retrieval of a separated instrument extending beyond the root canal using the Masserann kit assisted by magnification.

Case Report

A 35-year-old male patient reported to the Department of Conservative Dentistry and Endodontics with a complaint of pain for 1 week with respect to lower front teeth region. The patient gave a history of severe pain, which occurred 1 week back, for which he visited a private clinic where the treatment was initiated. Since the treatment was already initiated, it was decided to first take a radiograph before clinical examination. Radiographic examination revealed a separated lentulo spiral extending along the entire length of the root canal with 1–2 mm of it extending beyond the apex in #31 as shown in [Figure 1]a, which was confirmed on clinical examination as shown in [Figure 2]a. Radiograph was also suggestive of the widening of periodontal ligament space in #31, #32, and an initiated root canal treatment in #32. The diagnosis made was symptomatic apical periodontitis in #31 and chronic apical periodontitis in #32.

Figure 1: (a) Preoperative radiograph showing lentulo spiral separated in the root canal system in #312. (b) Radiograph suggestive of complete retrieval of lentulo spiral from #312. (c) Master cone radiograph of #31 and #322. (d) Radiograph showing obturated root canal system in #31 and #32

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Figure 2: (a) Preoperative photograph showing blockage in tooth #311. (b) Postoperative photograph showing tooth restored with a crown

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The patient was explained about the preexisting condition of the tooth. The treatment plan decided for the patient was retrieval of separated instrument from the root canal system in #31, followed by completion of root canal treatment in #31 and #32.

First visit

Treatment was started after obtaining the written informed consent from the patient. #31 and #32 were isolated using a rubber dam (ColtèneWhaledent, Langenau, Germany). Access cavity preparation in #31 was modified to obtain straight-line access. On further exploration, it was found that two canals: buccal and lingual were present in both #31, #32, and the separated lentulo spiral was located in the buccal canal of #31. The position of the separated instrument was confirmed to be in the buccal canal using magnification (ADMETEC LOUPES, 3.2X). While trying to remove the instrument using Steiglitz forceps and braiding technique with H-file, the instrument was separating further, and hence, the decision was made to use tube-like systems, and here it was decided to use Masserann kit (Micro Mega, France). The Masserann kit consists of 14 hollow, color-coded, and end-cutting trephine burs (size 11–24) of increasing sizes having a range of diameter from 1.1 to 2.4 mm and two extractors of diameter 1.2 mm and 1.5 mm, respectively, having a plunger rod (stylet) within it.^[8] Modified gates glidden drills (Mani Inc., Japan) were used successively to expose the coronal end of the separated fragment. Preselected trephine bur of 1.2-mm diameter latched into slow-speed contra-angle handpiece (NSK, Japan) was used to create a trough around the exposed coronal fragment by removing the surrounding root canal dentin in the counterclockwise direction. It was ensured radiographically that trephine was centered in the buccal root canal in #31. The extractor tube of 1.2-mm diameter was positioned in the groove around the coronal fragment, and the plunger rod was rotated inside the extractor tube in a clockwise direction to grasp the fragment against its wall. Once a sufficiently firm grip was achieved manually, the entire Masserann assembly was rotated in the counterclockwise direction and withdrawn to detach the separated fragment from the dentin. The removal of the entire length of the fragment was confirmed radiographically, as shown in [Figure 1]b. The working length was then confirmed using Intra-oral periapical radiograph (IOPA) radiograph. The biomechanical preparation was modified in both the canals in #31 and #32. Following which calcium hydroxide with iodoform paste was used as an intracanal medicament (Metapex, META Biomed Co. Ltd., Korea).

Second visit

In the subsequent visit, gutta-percha master cones were selected (ProTaper, Dentsply Maillefer) and verified radiographically, as shown in [Figure 1]c. Obturation was done using gutta-percha cones and AH PLUS sealer (De Trey Dentsply, Konstanz, Germany) in #31 and #32, as shown in [Figure 1]d. Post endodontic restoration was done using composite (SDR^™ composite, Dentsply). As shown in [Figure 2]b, the temporary crown was given to prevent vertical fracture of the tooth as its crown structure was compromised due to dentin removal. It was further replaced by definitive restoration in #31, #32.

Discussion

Prognosis of a tooth when endodontics is performed is not directly endangered by the instrument separation as an endodontic mishap but by the remnant microorganisms in the root canal system due to the mishap. The separated instrument blocks the root canal system, thus preventing adequate cleaning, shaping, disinfection, and achievement of fluid-tight seal of the root canal system. The prognosis in cases of the instrument separation thus depends on factors such as the vitality of tooth (vital/nonvital and symptomatic/asymptomatics), accessibility of tooth, stage of biomechanical preparation at which instrument separation has occurred, location of the separated instrument in the root canal with respect to canal curvature and closeness to the root apex, the taper of the instrument, and type of alloy of which the instrument is comprised.^[9],[10] According to Panitvisai et al., the presence of periapical lesion acted as the main factor affecting prognosis in such cases.^[11]

Common causes of instrument separation include variations in the root canal anatomy, radius of canal curvature, restricted access, unacceptable use of instruments, manufacturing defects, excessive use of endodontic instruments, use of rotary instruments without having an adequate glide path and straight-line access, improper torque and speed of rotation while using rotary instruments, and limited practitioners experience.^[1],[3],[5] Straight canals have a greater prevalence of torsional stress and torsional failure, as proved by Yum et al.^[12]

Furthermore, lentulo spiral is an engine-driven paste carrying instrument made from spring stainless steel with consistently placed spirals. It has tightly wound safety coils at the base of the shank. It has a tapered (2%) design to improve material distribution and air bubble release during use. Nevertheless, these paste fillers should be used prudently as they have a very low fracture resistance to torsional fatigue,^[13] and its engagement in the root canal wall at any stage may result in separation, as seen in this case report.

There are four approaches when managing a case of the separated instrument. These include bypassing the separated fragment plus incorporating the same in the root canal filling; retrieval of the separated instrument; leaving the separated instrument in the canal and treating the remaining portion of the canal, and surgical management of separated instrument involving either the removal of the separated instrument, radisection, or intentional replantation.^[5]

Retrieval of the separated instrument depends on:

tooth-related factors such as the type of tooth (anterior/posterior), length of root, dentin thickness, the position of instrument separation, the curvature of the root, location of the separated instrument in relation to canal curvature, and any aberration in canal anatomy^[5],[8],[14]
separated instrument-related factors such as the length of the separated instrument, type of file (H-file/K-file/reamer/lentulo spiral), and the metallurgical alloy of the instrument (Ni-Ti/Stainless steel)^[5]
equipment-related factors such as availability of different retrieval systems, adequate illumination, and magnification aids such as loupes and microscope^[5]
operator-related factors such as expertise and knowledge of clinician regarding various retrieval systems available to enable efficient decision-making, depending on the case of separated instrument^[4],[5]
patient-related factors such as the extent of mouth opening, accessibility to the tooth, patient's anxiety level, patient's motivation to save the tooth, and financial constraints, if any.^[5]

Based on the above-mentioned factors, different success rates for retrieval of the separated instrument have been noticed. The success rate has been seen to be limited to 50% in maxillary and mandibular premolars when compared to other tooth types.^[14] 59%, 69%, and 100% success rates have been observed when attempting to remove the instrument from the apical, middle, and coronal thirds of the root canal, respectively.^[15] Further, a success rate of 52%, 58%, and 82% has been observed depending on the location of the separated instrument, i.e, beyond the root canal curvature, inside the canal curvature and straight root canal, respectively.^[14] Depending on the curvature of the root canal, the success rate for retrieval ranges from 67% (21°–31°) to 74% (0°–10°).^[14] The success rate is also determined by the type of instrument. The success rate reported for H-files retrieval was 67%, while that for the lentulo spiral and reamer type instruments was 93% and 76%, respectively.^[14] Success rate ranging from 44% to 73% has been reported with the use of Masserann kit for posterior and anterior teeth, respectively,^[16] while the range of 67% to 95% has been reported with the use of ultrasonics.^[17],[18] The success rate for retrieval of instrument depending on its length ranges from 62% for a length shorter than 5 mm to 89% for 10.5–15 mm length.^[14]

Bypassing an instrument separated in the root canal is one of the methods to manage such a case and is a safer approach as it does not require excess removal of dentin around the instrument to access it, which is required in the case of its retrieval. Furthermore, it is a precursor step for retrieval of the separated instrument, especially if ultrasonics is to be used.^[4]

Bypassing the separated instrument was not attempted in the present case as the instrument was separated along the full length and was also seen extending beyond the root canal and was accessible coronally to allow the creation of a trough for the placement of extractor tube of Masserann. According to Suter et al.,^[19] there are high chances (57%) of secondary separation of lentulo spiral during its retrieval using ultrasonics. The Masserann kit is preferably used in the teeth having straight root canals and easy accessibility.^[7] Hence in the present case, the decision was made to remove the separated instrument using Masserann kit as straight line access was easily achievable to expose the coronal end of the instrument, hence allowing centering of trephan to grip the exposed fragment. The extractor tube of Masserann kit has a locking mechanism, thus providing strong retention and enabling gripping of even a separated instrument wedged in the root canal.^[20] The Masserann kit allowed easy gripping of the fragment in this case by removal of peripheral dentin and cautious removal of the instrument along the long axis of the root. The entire procedure was aided with magnification and regular radiographic assessment to enhance the visualization and keep the trephine centered over the instrument in the canal. Magnification also prevents any further endodontic complications which may occur during instrument retrieval like consequential separation of the instrument while its retrieval, especially using ultrasonics,^[19] perforation of the tooth,^[21] excessive removal of the dentin leading to tooth fracture,^[21] extrusion of separated instrument periapically,^[22] separation of ultrasonic file or tip,^[22] and damage to periodontal tissues due to the high temperature generated during the use of ultrasonics.^[6]

Adequate steps should be followed while performing root canal treatment to prevent instrument separation and its sequalae. Emphasis should be laid down on straight-line access, preparation of glide path, prevention of instrument overuse, avoiding the use of rotary instruments in complicated canal anatomy, and using recommended torque-controlled motors with rotary files.^[19],[23]

Conclusion

Instrument separation is an endodontic mishap which in itself does not affect the prognosis of the tooth. Other related factors such as preexisting endodontic lesion, microbial load in the root canal at the time of instrument separation, stage of disinfection at which instrument separation has taken place, accessibility of the tooth as well as of the separated instrument, and quality of obturation after the mishap have a long-term bearing on the prognosis of the tooth. Therefore, all the steps of root canal treatment should be meticulously followed to avoid such mishaps. If such mishap occurs, all factors that affect long-term prognosis of the tooth should be kept in mind while deciding the treatment modality. Instrument retrieval is by far the best option, but again, it should be precisely performed to prevent sequelae of retrieval in itself.

Declaration of patient consent

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

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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