Case study cover on blue background; title about a microscopic re-root canal treatment with a dental model on the right.

Preserving a Natural Tooth Through Precision Endodontics and Microscope-Assisted Care

PATIENT PROFILE

Age

42 years

Gender

Male

Occupation

Senior Project Manager

City

Bangalore

Presenting Complaint

Persistent dull ache and intermittent swelling around the lower left first molar. Previously advised tooth extraction at two separate clinics.

Diagnosis

Separated endodontic file (NiTi rotary instrument) in the middle third of the mesial root canal of tooth #36 (lower left first molar). Chronic periapical infection associated with incomplete prior root canal treatment.

Duration of Issue

Root canal treatment attempted 14 months prior at a general dental clinic. Pain and swelling recurring over the past 6 months.

Previous Treatments

Incomplete root canal treatment at an external clinic. Two courses of antibiotic therapy. Advised extraction by two subsequent treating dentists.

Treatment Period

January 2025- February 2025

Outcome

Excellent  tooth preserved, file retrieved, canals obturated, crown placed.

 

THE PROBLEM

Clinical Background

The patient had undergone a root canal treatment on tooth #36 (lower left first molar) approximately 14 months prior to his presentation at Dental Clinic in Bangalore. During that procedure, a nickel-titanium (NiTi) rotary file — a flexible instrument routinely used to clean and shape root canals had fractured within the mesial root canal and been left in situ. The treating dentist at the time had been unable to remove it and had continued treatment around the separated segment, partially obturating the canal before placing a temporary restoration.

Over the following months, the patient experienced recurring episodes of pain and swelling. He visited two additional dental clinics seeking a second opinion. Both clinicians independently advised that extraction was the only viable option, citing the difficulty of removing a fractured instrument from a curved canal and the risk of root perforation or fracture during any retrieval attempt. The patient was unwilling to lose the tooth and sought further consultation.

He arrived at Aspire Dental Clinic after conducting research into specialist endodontic care in Bangalore. His primary question at the initial consultation was direct: could the tooth be saved?

Why Fractured File Retrieval Matters

Separated endodontic instruments are among the more challenging complications in root canal treatment. A fractured file within the canal prevents complete debridement and disinfection of the root canal system. The retained metallic segment creates a physical obstruction that harbours bacteria and perpetuates periapical infection, as was evident in this case. Without removal, the long-term prognosis of the tooth is significantly compromised.

Retrieval is not always straightforward. The success of any removal attempt depends on the location of the fragment within the canal, the degree of root curvature, the length and diameter of the fragment, and the surrounding dentinal thickness. Cases involving fragments in the middle or apical thirds of curved canals are considered high risk. The operating microscope is the critical technology that converts these cases from near-impossible to clinically achievable.

CONSULTATION AND TREATMENT PLAN

Pre-Treatment Assessment

A comprehensive endodontic evaluation was conducted by Dr. Darshit Patel, MDS Endodontics, Certified Implantologist, prior to confirming whether retrieval was viable and safe. The assessment protocol included:

  • Detailed clinical examination including percussion, palpation, and probing of the affected tooth.
  • Periapical digital radiographs to determine fragment position, length, and the degree of canal curvature.
  • Cone Beam Computed Tomography (CBCT) imaging to assess the three-dimensional position of the fragment, residual dentinal thickness, proximity to the root bifurcation, and the extent of periapical pathology.
  • Assessment of existing coronal restoration and access cavity dimensions.
  • Medical history review — no systemic contraindications to endodontic treatment.

The CBCT scan confirmed the presence of a metallic fragment approximately 4 mm in length, lodged in the mid-third of the mesial root canal. The canal curvature was moderate (Schneider angle approximately 28 degrees). Residual dentinal wall thickness was adequate at the level of the fragment, and no evidence of ledge formation, root perforation, or root fracture was noted. A well-defined periapical radiolucency of approximately 3.5 mm was visible at the mesial root apex, consistent with chronic periapical abscess secondary to incomplete debridement.

Treatment Rationale and Risk Communication

The radiographic and CBCT findings supported an attempt at retrieval. The treatment plan was communicated to the patient in detail, including:

  • Planned approach: operating microscope-assisted file retrieval followed by complete canal debridement, disinfection, and obturation in two visits.
  • Limitations: retrieval is not guaranteed; if the fragment resists safe removal without risk of root fracture or perforation, the decision would be reassessed intraoperatively.
  • Alternatives: tooth extraction followed by dental implant placement, or extraction and bridge restoration.
  • Expected timeline: two to three clinical visits spanning four to six weeks.

The patient understood and accepted the treatment plan. Informed consent was obtained prior to commencing treatment.

Treatment Details

Step-by-Step Overview

Session 1: Access, Microscopic Assessment, and File Retrieval

Treatment was carried out under local anaesthesia (inferior alveolar nerve block, supplemented with buccal infiltration). The existing coronal restoration was removed and the access cavity refined to allow direct-line access to the fractured segment. Rubber dam isolation was placed for the entire duration of the procedure.

The operating microscope was deployed at 10x to 16x magnification throughout the retrieval phase. The canal was irrigated with sodium hypochlorite (3%) and the coronal portion of the canal was pre-flared using hand files to create a reproducible straight-line approach to the fragment. Ultrasonic instrumentation was used to progressively trephine around the coronal aspect of the fragment using a dedicated broken instrument removal kit (IRS System). The ultrasonic tip was operated at a low power setting under continuous saline irrigation to avoid heat generation and minimise dentinal stress.

After approximately 12 minutes of careful ultrasonic trephining, the fragment loosened and was expressed coronally. It was captured on the rubber dam for verification. The retrieved fragment measured 3.8 mm in length, consistent with the preoperative CBCT estimate. The entire working length of the mesial canals was now accessible. The apical portion of the canal was negotiated with a size 10 K-file and confirmed with an apex locator.

Full mechanical preparation of both mesial canals and the distal canal was completed using a crown-down technique with NiTi rotary files. Copious irrigation with sodium hypochlorite (3%), EDTA (17%), and saline was performed throughout. The canals were dried and an intracanal medicament (calcium hydroxide) was placed. A glass ionomer cement temporary restoration was placed. The patient was reviewed at one week  all symptoms had resolved.

Session 2: Obturation and Coronal Seal

At the second visit, the temporary restoration and calcium hydroxide medicament were removed. The canals were re-irrigated and confirmed dry with paper points. Master cone selection was confirmed radiographically. Obturation was performed using warm vertical compaction of gutta-percha with an AH Plus resin sealer. Post-obturation radiographs confirmed complete three-dimensional obturation of all canals, with no voids and an adequate apical seal. The access cavity was sealed with a bonded composite build-up. The patient was referred for fabrication of a full-coverage zirconia crown to protect the tooth long term.

Treatment Summary

Tooth Treated

#36 — Lower Left First Molar

Primary Procedure

Fractured endodontic file retrieval under operating microscope

Imaging Used

Digital periapical radiographs + CBCT (3D)

Fragment Location

Mid-third, mesial root canal

Fragment Length Retrieved

3.8 mm (NiTi rotary file segment)

Retrieval Method

Ultrasonic trephining (IRS System) under 10–16x microscope magnification

Obturation Method

Warm vertical compaction, AH Plus sealer

Number of Sessions

Two clinical visits

Total Treatment Duration

Approximately 4 weeks (January – February 2025)

Complications

None  no perforation, no root fracture, no ledge formation

Post-Endodontic Restoration

Full-coverage zirconia crown

Technology Used

Operating microscope, CBCT, digital apex locator, ultrasonic IRS kit

Post-Treatment Results

The fractured instrument was successfully retrieved without complication. All root canals were completely debrided, disinfected, and obturated in two visits. The patient was asymptomatic at both the one-week and four-week reviews. The periapical radiograph taken at the four-week review showed the beginning of periapical healing, with early reduction in the size of the previously noted periapical radiolucency.

The full-coverage zirconia crown was fabricated and cemented within four weeks of obturation. At the three-month clinical review, the tooth was fully functional with no symptoms of pain, swelling, or sensitivity. The patient reported complete return to normal chewing function on the treated side.

Outcomes at a Glance

Outcome

Status

Notes

Fractured File Retrieved

✔ Achieved

Complete 3.8 mm NiTi segment retrieved intact

Canals Fully Debrided

✔ Achieved

All three canals to working length

Periapical Infection

⟳ Resolving

Radiographic healing confirmed at 3-month review

Root Integrity

✔ Maintained

No perforation, crack, or fracture

Tooth Preserved

✔ Achieved

Extraction avoided

Crown Placed

✔ Completed

Zirconia crown, cemented within 4 weeks post-obturation

Patient Symptoms

✔ Fully Resolved

Asymptomatic at all post-treatment reviews

Complications

None

—

 

PATIENT FEEDBACK

“Two dentists had already told me to get the tooth out. I had almost accepted it. I found Aspire Dental while searching specifically for someone who could remove a broken file. Dr. Darshit was straightforward — he told me he could not guarantee the result before he saw the scans, but after the CBCT he said he was confident we could try. The procedure itself was done in two visits and I felt no pain at any point. When he showed me the fragment he had removed, I could not believe it. My tooth is still there, fully functional, with a proper crown. I wish I had come here first.

Post-Treatment Care and Follow-Up Protocol

Instructions Provided to the Patient

  • Avoid hard or sticky foods on the treated side for two weeks following crown cementation.
  • Maintain standard oral hygiene: twice daily brushing with a soft-bristle toothbrush and daily flossing around the crown margins.
  • Attend scheduled follow-up reviews at one month, three months, and twelve months post-treatment.
  • Report immediately if any return of pain, swelling, or sensitivity is experienced.
  • Annual radiographic review of the treated tooth to monitor ongoing periapical healing.

Clinical Notes: The Role of the Operating Microscope

The operating microscope is not an accessory in cases of fractured instrument retrieval  it is the foundational technology that makes the procedure possible with an acceptable margin of safety. At standard clinical vision, the orifice of a root canal is a small, dark aperture. At 10x to 16x magnification under coaxial illumination, the clinician can visualise the canal walls, the coronal aspect of the fractured segment, and the precise path of the ultrasonic tip in real time.

The ability to work under direct vision prevents the inadvertent removal of excessive dentinal structure, which would compromise root strength. It allows the ultrasonic tip to be directed precisely circumferentially around the fragment rather than applying misdirected force that can displace the fragment apically or cause perforation. In this case, the microscope allowed retrieval of a fragment at the mid-third of a moderately curved root — a case that would be considered untreatable without magnification.

Follow-Up Timeline

Timeframe

Clinical Status and Actions

1 Week Post-Retrieval

Asymptomatic. Canals dried, calcium hydroxide placed, temporary restoration sealed.

4 Weeks (Session 2)

Obturation completed. Post-op radiograph confirmed complete fill. Composite core placed.

8 Weeks

Zirconia crown fabricated and cemented. Occlusion verified. Patient pain-free.

3 Months

Clinical and radiographic review. Periapical radiolucency reducing. Full function restored.

12 Months (Planned)

Annual review to confirm complete periapical healing and crown integrity.

Aspire Dental’s Microscope Protocol

At Aspire Dental Clinic, all endodontic procedures, including primary root canal treatment, re-root canal treatment, and complex retrieval cases, are performed under the operating microscope. This approach is consistent with the highest standards of contemporary endodontic practice and is why the clinic is a recognised referral destination for complex endodontic cases across Whitefield and Bangalore.

Frequently Asked Questions

NiTi rotary files fracture due to metal fatigue in curved canals, torsional stress when the tip locks, or use beyond their recommended lifespan. It is a recognised risk of rotary instrumentation, particularly in narrow or curved canals.

No. Success depends on the fragment location, canal curvature, fragment length, and remaining dentinal thickness. Fragments in the coronal third are easier to retrieve; those in the apical third of a curved canal carry higher risk. CBCT assessment is essential before any attempt.

Without magnification, retrieval is effectively blind. The microscope provides direct visualisation of the fragment so the ultrasonic tip can be directed precisely around it. It also lets the clinician stop immediately if perforation risk increases — something that is not possible without clear visual feedback.

If retrieval is unsafe, a “bypass” technique may allow cleaning around the fragment. If neither is feasible, the tooth prognosis is reassessed and extraction with implant replacement may be the next step.

In most cases, yes. Posterior root-canal-treated teeth are structurally weakened. A full-coverage crown significantly reduces the risk of cusp fracture under normal chewing loads.

Yes. If extraction has been recommended for a tooth with a fractured file, consult a specialist endodontist with access to CBCT and an operating microscope. Many teeth deemed untreatable in a general setting can be managed at specialist level.

Disclaimer: This page is for informational purposes and not for promotional use.