Journal of Shandong University (Health Sciences) ›› 2019, Vol. 57 ›› Issue (3): 85-90.doi: 10.6040/j.issn.1671-7554.0.2018.1001

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A cone-beam computed tomographic study on the distolingual root of the permanent mandibular first molars

NIE Xiaokun1,2, HAO Xinyu3, ZHANG Shucun4, GE Tangna5, XIONG Shijiang1,2   

  1. 1. Shandong Provincial Key Laboratory of Oral Tissue Regeneration, Jinan 250012, Shandong, China;
    2. VIP Department, School of Stomatology, Shandong University, Jinan 250012, Shandong, China;
    3. Department of Pediatric Dentistry, School of Stomatology, Shandong University, Jinan 250012, Shandong, China;
    4. Department of Endodontics, Chengxi Branch of Hospital of Stomatology, Shandong University, Jinan 250021, Shandong, China;
    5. Department of Endodontics, Hospital of Stomatology, Shandong University, Jinan 250012, Shandong, China
  • Published:2022-09-27

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Abstract: Objective To explore the incidence, curvature and anatomy of pulp floors of the distolingual roots of permanent mandibular first permanent molars in order to provide theoretical guidance and basis for root canal therapy. Methods The cone-beam computed tomography(CBCT)images of 1 164 permanent maxillary first molars with distolingual roots were measured. The incidence of distolingual roots, the distance between root canal orifices, DB-DL-ML angle and curvature of distolingual roots were determined. Results (1) The incidence of distolingual roots was 25.60%, and the incidence on the right side was higher than that on the left side(P<0.05). There was no significant difference in the incidence between male and female(P<0.05). (2) The incidence of three-rooted and two-rooted mandibular first permanent molars was 25.60% and 22.68%, respectively. There were significant differences between the two types in DL-DB distance and DB-DL-ML angle (P<0.05). (3) The curvatures of the distolingual root canal were greater in the bucco-lingual view(11.60±10.05)° than in the mesio-distal view(30.19±13.48)°(P<0.05). The distolingual root canal bending was mostly seen in the middle third of the root. Conclusion The incidence of distolingual roots of mandibular first molars is high, and the incidence on the right side is higher than that on the left side. The location of DL root canal orifices of three-rooted molars is farther from DB root canal orifice than that of two-rooted molars with four canals. DB-DL-ML angle is sharper in the 山 东 大 学 学 报 (医 学 版)57卷3期 -聂晓琨,等.下颌第一恒磨牙远舌根的锥形束CT研究 \=-three-rooted molars and the distolingual roots are curved. The curved parts are usually located in middle third, and the curvature in the mesio-distal view is severe.

Key words: Permanent mandibular first molars, Distolingual root, Cone-beam computed tomography, Incidence, Anatomy of the pulp floors, Curvature

CLC Number: 

  • R781
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