Indian Journal of Dental Research

: 2011  |  Volume : 22  |  Issue : 5  |  Page : 736-

Displacement of endodontic instruments in inferior alveolar canal

Nitasha Gandhi, Sumir Gandhi, Saurab Bither 
 Department of Oral and Maxillofacial Surgery, Christian Dental College, CMC, Ludhiana, Punjab, India

Correspondence Address:
Sumir Gandhi
Department of Oral and Maxillofacial Surgery, Christian Dental College, CMC, Ludhiana, Punjab


Endodontic instrument breakage is a common occurrence during root canal treatment but the displacement of the separated instrument into the inferior alveolar canal is rare and has never been reported. We hereby present an unusual case of displacement of a separated instrument in the inferior alveolar canal and its retrieval by a simple technique.

How to cite this article:
Gandhi N, Gandhi S, Bither S. Displacement of endodontic instruments in inferior alveolar canal.Indian J Dent Res 2011;22:736-736

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Gandhi N, Gandhi S, Bither S. Displacement of endodontic instruments in inferior alveolar canal. Indian J Dent Res [serial online] 2011 [cited 2023 Sep 23 ];22:736-736
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Full Text

Endodontic instrument breakage is a common problem while doing root canal treatment. The separated instruments may not require retrieval but they can get displaced into the maxillary or inferior alveolar canal and can lead to symptoms. When instrument breakage occurs, it immediately provokes despair, anxiety, and the hope that nonsurgical retreatment techniques exist to liberate the instrument from the canal. Endodontic instrument breakage is a common complication of root canal treatment. Various reasons have been sought for the breakage of the endodontic instruments like excess torque, or cyclic fatigue, or both, aggressive movements, such as penetrating the canal too rapidly or forcing an instrument to an arbitrary length or among a sharp curve and inappropriate rotational speed. [1] In a study carried out by Spili et al., for the frequency of instrument fracture and its impact on treatment outcome, an overall prevalence of 3.3% of retained fractured instruments had been observed in 8460 endodontically treated cases. [2] The potential to safely remove a broken instrument is further guided by anatomy, including the diameter, length, and curvature of the canal, and additionally limited by root morphology, including the thickness of dentin and the depth of external concavities. Various instrumentation techniques have been employed for the removal of the separated instruments during the root canal treatment-gates glidden drills, piezoelectric ultrasonics, ProUltra® ENDO-3, 4, 5, 6, 7, 8 Tips (Dentsply Tulsa Dental; Tulsa, Oklahoma), Instrument Removal System (iRS™) (Dentsply Tulsa Dental; Tulsa, Oklahoma). [3]

It is rare for a separated instrument to cause injury to the inferior alveolar neurovascular bundle as it has never been reported in the literature. However, a separated instrument can cause various degrees of neurological injuries ranging from neuropraxia to neurotmesis (Seddon's classification). [4] Such neurological injuries can also be classified as grade I to V according to Sunderland's classification. We present a case of iatrogenic grade I injury to the inferior alveolar nerve caused by the accidental displacement of a separated endodontic file into inferior alveolar canal and full neurological recovery after a simpler technique for its retrieval.

 Case Report

A 50-year-old female was referred to us with severe pain in the right mandibular region for the last 14 days. The pain was severe, lancinating, continuous, and not controlled by nonsteroidal anti-inflammatory drugs and opioids. On careful history examination, the patient told that she got root canal treatment done for right mandibular second premolar for intermittent pain possibly due to irreversible pulpits. The pain persisted even after the treatment and the patient was subsequently put on analgesics. After a span of 3 days the general practitioner took an intraoral periapical radiograph (IOPA) which revealed overextended obturation. The dentist removed the gutta percha but the patient did not get any relief from pain albeit the pain increased in severity and intensity. Subsequently, the tooth was extracted but the symptoms of the patient remained as such.

The patient consulted another general practitioner who took another IOPA which revealed the presence of a foreign body of around 2 mm near the inferior alveolar canal and its tip extending into the canal [Figure 1]. After thorough history examination and consultation with the previous general practitioner, he made a diagnosis of a separated endodontic instrument, which got displaced into the inferior alveolar canal while root canal treatment or extraction. Subsequently, the patient was referred for management.{Figure 1}

On clinical examination, we noticed a fresh extracted tooth socket (mandibular right second premolar). The patient was having severe radiating pain which was not completely relieved by analgesics. The intraoral periapical radiograph showed the separated endodontic instrument overlying the inferior alveolar canal. However, the patient did not have paresthesia. Based on the history, clinical, and radiological findings, we made a diagnosis of separated endodontic instrument, which caused injury to the inferior alveolar neurovascular bundle (Seddon and Sunderland grade I injury) [4] was made. After thorough clinical and radiological examination, we planned to retrieve the separated instrument from the canal.

The procedure was carried out under local anesthesia using 2% lignocaine with 1:2,00,000 adrenaline and I.V. sedation using Midazolam. Also, preoperative intravenous dexamethasone 8 mg was administered. Incision was made in the gingival crevice of the right first premolar and was extended till right first molar with releasing incisions on both sides and a trapezoidal full thickness mucoperiosteal flap was raised. Mental foramen with neurovascular bundle was identified and the buccal cortex of the socket was reduced just short of mental foramen with slow speed carbide bur under copious normal saline irrigation. Care was taken so that neurovascular bundle does not get damaged. Bone of roof of the canal was carefully reduced in the possible region of endodontic instrument [Figure 2]. The separated file end was visualized entangled into the neural tissue and it was retrieved [Figure 3] with the help of cotton pliers taking care not to push the instrument further deep into the neurovascular bundle.{Figure 2}{Figure 3}

Wound irrigation was done and primary closure was achieved using 3-0 black braided silk. Post-operatively, the patient was prescribed analgesics for 5 days to take care of the post-operative pain. Pain reduced in intensity and severity after 24 hours of the surgery and complete relief was achieved on the fourth day. Sutures were removed on the seventh day with no signs of any neural deficit. The patient is pain-free without any complications at 1-year follow-up [Figure 4].{Figure 4}


With the advent of rotary NiTi files, there has been an unfortunate increase in the occurrence of broken instruments and the factors contributing to breakage have been identified. [3] The consequences of leaving versus removing broken instruments from the canal have been discussed in the literature and a variety of approaches for managing these obstructions have been presented. [5]

When root canal treatment of a lower molar or premolar surpasses and/or overextends beyond the apical foramen and invades the periapical zone, the foreign material introduced within such a sensitive anatomical space may mechanically, thermally, or even chemically affect the inferior alveolar nerve. Calcium hydroxide-based sealers, Gutta percha, paraformaldehyde pastes and thermoplaticized gutta percha, are the materials which usually lead to extrusion accidents. [6],[7] But a thorough review of literature does not report any case of displacement of endodontic instrument into the inferior alveolar nerve canal.

Poor apical sealing, increased working length during mechanical preparation, and the previous existence of granuloma at the periapex which conditions the existence of an osteolytic area of a less dense bone in the periapical zone have been sought as the major reasons of overextension of the gutta percha periapically and can get further displaced into the inferior alveolar canal. But in the clinical case described here, the breakage of instrument and invading into the inferior alveolar canal showcases a poor endodontic technique.

Endodontic materials or instruments when displaced into the inferior alveolar canal can lead to various degrees of neurological deficit. [7],[8],[9] The separated instrument can cause nerve compression and lead to acute neurological symptoms as in our case, the patient had severe pain. In such cases, retrieval of foreign body from the inferior alveolar canal becomes mandatory. Removal of foreign body from the inferior alveolar canal is necessary for the complete recovery of nerve sensations and a better prognosis, if performed early. [9]

If the displaced instrument is in the region posterior to mandibular second premolar, saggital split osteotomy can be carried out, [7] while in the region anterior to it, a lateral decompression technique has to be followed. [10] Blanas has suggested an algorithm for the management of thermoplastic inferior alveolar nerve injuries. [6]

Saggital split osteotomy, which has been described in the literature to remove the displaced endodontic materials from the inferior alveolar canal, enables a considerable length of nerve to be exposed; damage of the nerve can be readily assessed and the presence and position of any toxic substances ascertained. [9] Lateral decompression carries the risk of inferior alveolar nerve trauma and hence can lead to temporary to permanent neural deficit. Moreover, both saggital split osteotomy and lateral decompression have to be carried out under general anesthesia. In our case, a separated file was displaced in the inferior alveolar canal in the second mandibular premolar region, so in order to avoid the above-mentioned complication we did the simpler procedure with no complication.


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