DT News - ASEAN - ASEAN Dentistry Award 2025 winners showcase: Best Case for Endodontics

Dr. Chun-Pei Lin

Fri. 14. August 2026

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Case Description

Chief complaint: Referred from a general dentist for further treatment of tooth #48.

History of complaints: The patient went to a general dentist due to dull pain over lower right posterior region for one week. However, after the endodontic emergency treatment of tooth #48, the patient was referred for further management of tooth #48 due to the curve roots.

Medical history : Denied any major systemic diseases and had no drug or food allergies.

Dental history : The 31-year-old female patient was referred to our clinic for tooth #48 root canal treatment due to curved root canals. She received tooth #46 extraction and full mouth orthodontic treatment two years ago. After tooth #46 extraction, teeth #47 and #48 were moved medially to close the space by her orthodontist.

Extra-oral examination: No abnormal findings.

Intra-oral examination: Tooth #48 was status post previous initiated therapy, with occlusal coronal 1a temporary restoration and mesio-occlusal composite resin filling.

• Abscess (-) / sinus tract (-)
• Percussion pain (-), palpation pain (-)
• Probing depth : within normal range.
• Mobility : within normal range.

Radiographic findings:
• Tooth #48 with curved root canal toward distal side could be identified.
• A 6mm x 4mm periradicular radiolucent lesion was noted at apical third.
• A radiopaque image was found at mid-root level, an intra-canal separated instrument was highly suspected.

Differential diagnosis:
Based on the clinical and radiographic findings and according to the American Association of Endodontists Terminology, the diagnosis of tooth #48 was:
• Pulpal diagnosis: Previously initiated therapy.
• Periradicular diagnosis: Asymptomatic apical periodontitis.

Fig. 1a: Preoperative microscopic view of the pulp chamber showing a separated endodontic instrument obstructing the canal orifice.

Fig. 1b: Straight-line access established under the dental operating microscope, with the coronal portion of the separated instrument exposed after removal of the dentinal triangle using the START-X #3 ultrasonic tip.

Fig. 1c: The separated instrument was bypassed with a pre-curved #10 K-file to establish a negotiable pathway before retrieval.

Fig. 1d: Following successful bypass, the separated instrument was retrieved using an ET25 ultrasonic tip with counterclockwise activation under microscopic visualization.

Treatment planning:
• Non-surgical root canal treatment of tooth #48 was planned.
• Attempt to bypass or remove the separated instrument.
• Tooth #48 crown fabrication after root canal treatment.

Management:
Tooth #48 nonsurgical root canal treatment was performed under dental operating microscope. After root canal treatment was completed, then referred to a prosthodontist for crown fabrication. Regular follow-up was arranged to monitor the healing process of the apical lesion.

(1) Management of separated instruments:

• START-X #3 canal opening scouter ultrasonic instrument was applied for straight line access under dental operating microscope.
• After removed the dentinal triangle, the coronal part of the separated instrument was exposed.
• Bypassed the separated instrument with #10 K-file and enlarged the pathway with #15 and #20 K-files.
• ET25 ultrasonic instrument was applied with counterclockwise rotation around the separated instrument to remove it.

(2) Management of curved canals:

• The canal curvature angle of D canal was 45⁰ and ML canal was 61⁰ measured by Schneider’s method. Both were belong to severely curved group.
• Negotiated the root canal to working length with pre-curved #10 K-file.
• Glide path established with PathFiles in the sequence of #13/.02, #16/.02 and #19/.02 to working length.
• ProTaper NEXT X1(#17/.04) and X2(#25/.06) Ni-Ti rotary files were used for root canal cleaning and shaping.

(3) Cleaning and shaping of the c-shaped root canal system:

• Shaping: The instruments were all used with X-Smart Plus endodontic motor with the settings of the manufacture’s recommendations.
* ML: 20 mm, IAF: #10, MAF: PTN X2 (#25/.06)
* B: 18.5 mm, IAF: #10, MAF: PTN X2 (#25/.06)
* D: 18 mm, IAF: #10, MAF: PTN X2 (#25/.06)
• Irrigation method: 2.5 % NaOCl and 17% EDTA irrigation were performed. Passive ultrasonic irrigation was performed.
• Calcium hydroxide as intra-canal medicament was applied to the root canal.
• Caviton and IRM were applied as coronal temporary sealing.

(4) Obturation and coronal sealing of the c-shaped root canal system:

• Pre-curved ProTaper NEXT Gutta-Percha X2 as master cones.
• Canals sealer with vertical compaction and thermoplastic injection techniques were performed to obturate the root canal.
• SDR and composite resin composite resin were placed for coronal restoration.
• The obturation and restoration procedures were operated under the microscope.

Definitive treatment:

(1) Post-treatment four month follow-up
• No clinical symptoms and signs were observed.
• The periradicular lesion decreased in size bone density.
• The patient was referred to a prosthodontist for crown fabrication.

(2) Post-treatment eight month follow-up
• No clinical symptoms and signs were observed.
• The periradicular lesion decreased in size bone density.

(3) Post-treatment 15-month follow-up
• No clinical symptoms and signs were observed.
• The periradicular lesion completely healed.

Fig. 1e: Radiographic assessment demonstrating severe canal curvatures of the distal and mesiolingual canals measured according to Schneider’s method prior to canal preparation.

Fig. 1f: Working length radiograph confirming successful negotiation of the severely curved root canals with endodontic files.

Fig. 1g: Master cone radiograph verifying the adaptation of pre-curved ProTaper NEXT X2 gutta-percha cones prior to obturation.

Fig. 1h: Postoperative radiograph demonstrating satisfactory obturation of the C-shaped root canal system and successful completion of nonsurgical root canal treatment.

Fig. 2a: Immediate postoperative periapical radiograph demonstrating satisfactory obturation of the C-shaped root canal system and coronal restoration following nonsurgical root canal treatment.

Fig. 2b: Four-month follow-up radiograph showing reduction in the periradicular radiolucency with increased bone density, indicating favorable periapical healing. The tooth remained asymptomatic and was referred for definitive crown fabrication.

Fig. 2c: Eight-month follow-up radiograph after crown placement demonstrating continued osseous healing and further reduction of the periradicular lesion. The tooth remained clinically asymptomatic.

Fig. 2d: Fifteen-month follow-up radiograph demonstrating complete periapical healing with normal bone architecture and successful long-term treatment outcome in the absence of clinical signs and symptoms.