|Year : 2018 | Volume
| Issue : 2 | Page : 88-92
Retrieval of a separated nickel–titanium instrument and a stainless steel H-file using a novel tube, loop and file technique
Nishant Vyavahare, Meera Kulkarni, Niranjan Desai
Department of Conservative Dentistry and Endodontics, Sinhgad Dental College and Hospital, Pune, Maharashtra, India
|Date of Web Publication||31-Dec-2018|
Dr. Meera Kulkarni
S.No. 44/1, Vadgaon Budruk, Off Sinhgad Road, Pune - 411 041, Maharashtra
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Instrument separation is one of the most common procedural errors that may occur during endodontic treatment. A separated instrument can create an obstruction in the root canal which can hinder the cleaning and shaping procedures. If an instrument separation takes place, an attempt should be made to retrieve the instrument and if retrieval is not possible, the instrument should be bypassed. Nickel–titanium (NiTi) instruments have several advantages, such as superelasticity and shape memory, which prompted their use in endodontics. Due to these characteristics, NiTi instruments have shown to preserve the original anatomy and shape of the root canal. However, the disadvantage is that they fail to show signs of fatigue prior to fracture unlike stainless instruments. This article describes a case report showing the successful use of a modified tube, loop and file technique for the retrieval of two separated instruments, from a maxillary lateral incisor of a 14-year-old male patient.
Keywords: Instrument retrieval, instrument separation, loop and file technique, tube
|How to cite this article:|
Vyavahare N, Kulkarni M, Desai N. Retrieval of a separated nickel–titanium instrument and a stainless steel H-file using a novel tube, loop and file technique. J Int Clin Dent Res Organ 2018;10:88-92
|How to cite this URL:|
Vyavahare N, Kulkarni M, Desai N. Retrieval of a separated nickel–titanium instrument and a stainless steel H-file using a novel tube, loop and file technique. J Int Clin Dent Res Organ [serial online] 2018 [cited 2019 Jun 17];10:88-92. Available from: http://www.jicdro.org/text.asp?2018/10/2/88/249132
| Introduction|| |
There are several unwanted procedural errors that clinicians may face during endodontic practice. These include strip perforations, ledging of the root canal walls, and separation of various endodontic instruments. The introduction of nickel–titanium (NiTi) instruments has revolutionized the way we shape the canal system. Despite the various advantages and increased use of NiTi instruments, the chances of procedural mishaps are much greater (1.3% and 10.0%, respectively) than that those of stainless steel instruments (0.25% and 6%, respectively). Various factors associated with the fracture of NiTi rotary instruments include absence of glide path, instrument design and technique, rotational speed, and canal curvature. Instrument breakage during treatment may also lead to considerable anxiety to the clinician. The success rate for retrieval of separated instruments has been found to be between 55% and 79%.
Various devices and techniques have been used which include the Masserann instrument retrieval kit (Micromega, France), Instrument removal system (Dentsply Tulsa Dental; Tulsa, OK), Post removal system (SybronEndo; Orange, California), and Cancellier Extractor Kit (SybronEndo, Orange California).
The use of ultrasonics as well as dental operating microscope for improved magnification has also proven to be a useful adjunct.
This article reports a case of separation of two instruments, one NiTi and one stainless steel Hedstrom file (H-file), using a novel tube, loop and file technique.
| Case Report|| |
A 14-year-old male patient reported to the department of conservative dentistry and endodontics with the chief complaint of a fractured instrument in the upper right lateral incisor. The patient was referred from the department of pediatric dentistry, where the file separation had taken place in the hands of an undergraduate student.
Clinical examination revealed an access cavity preparation with tooth 12 which was temporized. The tooth was in normal alignment with the adjacent teeth. The occlusion of the patient revealed a Class I molar relation with an anterior open bite. There was no tenderness to percussion or palpation, no noted swelling, and no sinus tract was seen. Periodontal examination revealed mobility, probing depth, and gingival tone within the normal limits. On radiographic examination, a NiTi instrument was visible, 1.5–2 mm beyond the apex of the tooth [Figure 1]a. The beginning of a periapical radiolucency was also seen in relation to the tooth.
|Figure 1: (a) preoperative radiograph of tooth 12. (b) Attempt to retrieve file using tube and loop technique. (c) Separation of H-file during braiding technique. (d) Retrieval of H-file. (e) Retrieval of ProTaper S1. (f) Length of retrieved files. (g) Placement of calcium hydroxide dressing in the canal. (h) Placement of MTA plug. (i and j) Reinforcement using fiber post and resin core buildup|
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An informed consent was taken from the patient prior to starting the procedure. On removal of the temporary restoration, a weeping canal was seen. The canal was irrigated with 3% sodium hypochlorite (Prime Dental Products Pvt. Ltd) and dried with paper points (Sure Dent Corporation, Korea). Calcium hydroxide (RC Cal, Prime Dental Products Pvt., Ltd.) dressing was placed and the patient was recalled after 7 days. The tip of the NiTi instrument was visible when viewed under ×8 magnification of an endodontic microscope (Moller-Wedel International, Germany).
At the first appointment, under rubber dam isolation, a straight-line access was created using ProTaper SX (Dentsply Maillefer). Following this, a staging platform was created using a modified tip of a size 2 Gates Glidden (Mani Inc., Japan) drill at a speed of 300 rpm along with ultrasonic activation. At its maximum cross-sectional diameter, the bud of the Gates Glidden drill was altered by cutting it perpendicular to its long axis. Since length of the file was more than 5 mm and also the file was engaged in the canal and periapical bone, ultrasonic efforts proved to be unsuccessful. In this scenario, the file should be retrieved using a retrieving device rather than ultrasonic activation as suggested by Terauchi et al.,
An attempt was made using a tube and file technique, where the tube was encased into the tip of the file and another H-file (Mani Inc., Japan) of size 25 was passed down the length of the tube and engaged into the assembly which was then pulled out. However, the file was further pushed beyond the apex of the tooth during the process. Then, an attempt was made using a loop prepared with a ligature wire along with the tube [Figure 1]b. However, the instrument kept slipping from the loop as it had threaded into the dentin and was bound to the canal walls. Following this, as the file was positioned deeper in the canal, the braided technique was used, where two H-files of size 30 were twisted around the instrument in order to engage it and pull it out of the canal. During this procedure, one of the H-files was separated [Figure 1]c.
Finally, as a last resort, an attempt was made where the tube, loop and file technique was used. The loop was prepared by passing two free ends of a 0.14-mm stainless steel wire through a 22G calcium hydroxide delivery needle from the open end until both the free ends of the wire slid out of the hub end. The loop was first passed around the H-file. Once the loop had engaged around the file, another H-file of size 30 was passed down the length of the tube until it wedged tightly between the instrument and the internal lumen of the microtube. The loop was tightened around the upper free part of the fragment using a small mosquito hemostat and the entire assembly was pulled out together and thus the separated H-file was retrieved [Figure 1]d. Liquid ethylenediaminetetraacetic acid (Largal Ultra Septodont, UK) was used as an adjunct for softening dentin around the separated instrument, facilitating the placement of the file into the assembly for the removal of the fragment. The NiTi instrument was retrieved in a similar manner using the tube, loop and a size 30 H-file [Figure 1]e and [Figure 1]f.
Following retrieval of both the instruments, calcium hydroxide (RC Cal, Prime Dental Products Pvt., Ltd.) was placed in the canal for 2 weeks [Figure 1]g and the cavity was sealed using IRM cement (Dentsply Sirona, USA). After 2 weeks, the calcium hydroxide was rinsed from the canal, the canal was dried using paper points (Sure Dent Corporation, Korea), and a 5-mm MTA (Medicept Dental India Pvt., Ltd.) plug was placed in order to achieve an apical closure [Figure 1]h.
Three fiber posts (Hi-Rem, Overfibers) were then placed in the remaining root canal space and core buildup was carried out using dual-cure resin-luting cement (ParaCore, Coltene Whaledent Pvt., Ltd.) [Figure 1]i and [Figure 1]j.
Finally, after 1 week, as the patient was asymptomatic, the tooth was restored using a porcelain-fused-to-metal crown [Figure 2].
| Discussion|| |
Intracanal separation of endodontic instruments results in blockage to the apical terminus and hinders the cleaning and shaping of the root canal system, resulting in adverse effects on the treatment outcome.,,
In a study by Strindberg, 19% reduction rate of healing of periapical tissues was seen these 4 cases. Thus, it can be speculated that the prognosis would be poor in the presence of periapical lesions. Similarly, Grossman in his study viewed 66 cases with an average follow-up of 2 years and has reported that when periapical lesions were present, the success rate was considerably reduced to 47% in the presence of separated instruments.
The success rate also depends on the stage at which the cleaning and shaping of the canal has taken place., In the current case, an S1 ProTaper file (Dentsply Maillefer) had separated; hence, adequate cleaning and shaping of the canal had not taken place. Separated instruments may function effectively as a filling material provided that the canals have already been cleaned and shaped and are ready for obturation.
There are several orthograde as well as surgical approaches for the management of separated endodontic instruments. Orthograde approaches include attempts to bypass the fragment, attempts to remove the fragment by mechanically engaging broken instrument, or cleaning/shaping and filling of the root canal to the level of the fragment. In the reported case, as the instrument had separated 1.5–2 mm beyond the apical foramen, in the initial stage of biomechanical preparation, it was not possible to bypass or fill the remaining root canal to the level of the separated fragment. As a result, removal of the instrument had to be carried out.
The following situations are more predictable for the removal of separated instruments:
- In maxillary teeth,
- In anterior teeth,,
- Location of the fragment before the root canal curvature,,,
- When the separation of the instrument has taken place in a straight or slightly curved root canal.,
Removal of the fractured fragment also becomes more predictable if a gap between the fragment and root canal walls is present. NiTi instruments fracture due to torsional failure and, the more the apical the fragment, the greater will be the challenge for the operator. In majority of the cases, files separate at their terminal extents among D3, D4, or D5.
It has also been observed that from the total length of the separated instrument, if more than one-third is exposed, the removal of the instrument becomes easy. However, the complications arise with NiTi instruments as they generate fracture more apically due to their flexibility, making their removal more difficult.
Compared to stainless steel instruments, NiTi rotary instruments tend to thread into the canal walls because of their rotary motion. In addition, if the canal is curved, the instruments lie against the outer root canal wall due to their flexibility and do not remain at the center of the canal.,,
The design of the separated instruments also plays an important role. K-files are easier to remove as compared to H-files. The design of the H-files makes their removal more challenging., These files have larger helix angle, deeper flutes, and greater positive rake angle. The cutting efficiency of these files is also greater compared to K-files, resulting in greater engagement with root canal walls at the time when separation occurs. Despite these challenges, the technique proved to be effective and both the instruments were successfully retrieved.
Finally, if there is good visualization and straight-line access, manipulation of retrieval instruments/devices safely and effectively becomes more easy. In this case, the dental operating microscope was used which proved to be a useful adjunct and helped minimize the chances of ledging which may give rise to potential areas of stress concentration that may contribute to vertical root fracture.
| Conclusion|| |
Separation of an instrument may place the clinician under stress and thus provoking him/her to attempt to remove the fragment. Hence, the best antidote for a separated file in a canal is prevention. It is important to discard endodontic instruments from time to time to minimize the chances of breakage. It is mandatory for the operator to adopt a measured methodological approach with utmost patience. The clinician must effectively and safely handle the devices and instruments used for removal of the separated instruments.
The line of treatment for the management of separated instruments is dependent on several factors such as the type of the instrument, its design, and length. There are several patient factors which need to be taken into consideration such as extent of mouth opening, limitations in accessing the tooth, time constraints, anxiety level, and motivation to retain teeth. The successful removal is a challenge that relies on the creativity of the operator as well as training, patience, and familiarity with techniques and instruments.
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
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]