Endodontic treatment of a two-rooted mandibular first premolar with four root canals: a case report

Abstract

Background: Mandibular first premolar has a complex and variable anatomy of the root canal system, which often leads to failure of endodontic treatment due to missing root canals. Identifying the complete structure of the root canal system to ensure that all root canals are perfectly cleared and filled becomes critical to the success of root canal therapy. This report introduced a unique case of endodontic treatment of a two-rooted mandibular first premolar in the buccolingual direction with a total of four canals.

Case presentation: An adult male patient with a lower left first premolar was diagnosed with acute apical periodontitis and treated with open pulp drainage in a general hospital. One day later, due to the complexity of the root canal structure, the patient was referred to our clinic for subsequent treatment. The tooth #34 was diagnosed with abnormal central cusp, apical periodontitis, and incomplete fracture through clinical and x-ray examinations. Cone-beam Computed Tomography (CBCT) results showed that the tooth #34 processed two roots with a buccolingual bifurcation and a total of 4 root canals: 1 lingual canal, 2 mesiobuccal canals, and 1 distobuccal canal. Notably, the buccal root presented a C-shaped configuration, and the mesiobuccal canals were of 2-1 type. The tooth was treated with microendodontics and crown restoration. One year after the treatment, the follow-up results showed that the tooth #34 was functioning normally without any abnormalities.

Conclusion: This report enhances our understanding of the anatomical variations in the root canal system of the mandibular first premolar and emphasizes the importance of CBCT in identifying anatomical variations within the root canal system. Clinicians must be aware of such changes in the mandibular first premolar during treatment to ensure a perfect treatment and better prognosis in clinical practice.

Keywords: anatomical variations; bicuspid; cone-beam computed tomography; dental operating microscope; root canal therapy.

Figure 1

Preoperative examination of tooth #34. (a) A probing perforation of the pulp of tooth #34; (b) A buccal crack on tooth #34 (red arrow); (c) There was an anatomical variation in the lower segment of the root canal on the x-ray image (red arrow).

Figure 2

Preoperative CBCT images of tooth #34. (a) The root of tooth #34 was buccolingually bifurcated in the middle 1/3 on the coronal plane; (b1) There were three canals within the buccal root, while there was only one canal within the lingual root; (b2) The two mesiobuccal canals fused into one at the apical region (2-1 type); (c1) The apical region of the mesiobuccal root canal was suspected to be calcified and non-patent on the sagittal plane; (c2) The buccal root exhibited a C-shaped configuration with a groove; (c3) The lingual root contained a single canal with a length of approximately 25 mm. (a) coronal plane; (b) axial plane; (c) sagittal plane. MB1, mesiobuccal1 canal; MB2, mesiobuccal2 canal; DB, distobuccal canal; Li, lingual canal.

Figure 3

Root canal preparation for tooth #34 under a dental operating microscope. (a) X-ray tracing showed that the MB2 canal had reached the working length; (b) The four canal orifices were exposed. MB1, mesiobuccal1 canal; MB2, mesiobuccal2 canal; DB, distobuccal canal; Li, lingual canal.

Figure 4

The root canal filling of tooth #34 under a dental operating microscope. (a) The canals were trial-fitted; (b) The filling of the root canals in the lower segment of the root bifurcation; (c) The upper segment was backfilled with gutta-percha; (d) The final coronal filling as presented in the inverted x-ray image; (e–g) The postoperative CBCT results showed that the root canals were filled densely and continuously without gaps on the coronal plane (e), axial plane (f), and sagittal plane (g) Follow-up visit 1 year after RCT. (h) The full crown restoration of tooth #34; (i–k) CBCT results showed that the four root canals were densely and evenly filled, with no apparent abnormalities observed in the periapical region on the coronal plane (i), axial plane (j), and sagittal plane (k).