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Biomechanical impact of different isthmus positions in mandibular first molar root canals: a finite element analysis

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Abstract

Objective

This study used image-based finite element analysis (FEA) to assess the biomechanical changes in mandibular first molars resulting from alterations in the position of the root canal isthmus.

Methods

A healthy mandibular first molar, characterized by two intact root canals and a cavity-free surface, was selected as the subject. A three-dimensional model for the molar was established using scanned images of the patient's mandibular teeth. Subsequently, four distinct finite element models were created, each representing varied root canal morphologies: non-isthmus (Group A), isthmus located at the upper 1/3 of the root (Group B), middle 1/3 of the root (Group C), and lower 1/3 of the root (Group D). A static load of 200 N was applied along the tooth's longitudinal axis on the occlusal surface to simulate regular chewing forces. The biomechanical assessment was conducted regarding the mechanical stress profile within the root dentin. The equivalent stress (Von Mises stress) was used to assess the biomechanical features of mandibular teeth under mechanical loading.

Results

In Group A (without an isthmus), the maximum stress was 22.2 MPa, while experimental groups with an isthmus exhibited higher stresses, reaching up to 29.4 MPa. All maximum stresses were concentrated near the apical foramen. The presence of the isthmus modified the stress distribution in the dentin wall of the tooth canal. Notably, dentin stresses at specific locations demonstrated differences: at 8 mm from the root tip, Group B: 13.6 MPa vs. Group A: 11.4 MPa; at 3 mm from the root tip, Group C: 14.2 MPa vs. Group A: 4.5 MPa; at 1 mm from the root tip, Group D: 25.1 MPa vs. Group A: 10.3 MPa. The maximum stress in the root canal dentin within the isthmus region was located either at the top or bottom of the isthmus.

Conclusion

A root canal isthmus modifies the stress profile within the dentin. The maximum stress occurs near the apical foramen and significantly increases when the isthmus is located closer to the apical foramina.

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Data availability

No datasets were generated or analysed during the current study.

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Acknowledgements

We also thank Medjaden Inc. for its assistance in the preparation of this manuscript.

Funding

This study was supported by the National Natural Science Foundation of China (No.81960207).

Author information

Authors and Affiliations

  1. Department of Stomatology, Xuchang Central Hospital, Xuchang, 461000, China

    Qingting Yao

  2. Department of Endodontics, People’s Hospital of Xinjiang Uygur Autonomous Region, Urumqi, 830001, China

    Youmei Zhuang & Shuhui Li

  3. Department of Dentoalveolar Surgery, People’s Hospital of Xinjiang Uygur Autonomous Region, Urumqi, 830001, China

    Yaerken Aji

  4. Postgraduate College of Xinjiang Medical University, Urumqi, 830054, China

    Qilin Zhang & Yixiang Luo

Authors
  1. Qingting Yao
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  2. Youmei Zhuang
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  4. Qilin Zhang
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  5. Yixiang Luo
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  6. Shuhui Li
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Contributions

Conceptualization, SH Li and QT Yao; Software, YM Zhuang and Yaerken Aji; methodology, SH Li , QT Yao and Yaerken Aji; investigation, QT Yao, QL Zhang, and YX Luo; project administration, SH Li and YM Zhuang; writing–original draft, SH Li, QT Yao, and YM Zhuang; writing–review and editing, SH Li, QT Yao, YM Zhuang, and Yaerken Aji. All authors contributed to the article and approved the submitted version.

Corresponding author

Correspondence to Shuhui Li.

Ethics declarations

Ethics approval and consent to participate

This study was approved by the Ethics Committee of the People's Hospital of the Xinjiang Uygur Autonomous Region (No. KY2018011852). Informed consent was obtained from the patient before sample collection.

Competing interests

The authors declare no competing interests.

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Key points

1. Developing finite element models with isthmus at various locations within root canals.

2. Offering in-depth insights into the biomechanical characteristics of mandibular molars.

3. Evaluating the biomechanical effects of the varied isthmus positions within root canals.

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Yao, Q., Zhuang, Y., Aji, Y. et al. Biomechanical impact of different isthmus positions in mandibular first molar root canals: a finite element analysis. Clin Oral Invest 28, 311 (2024). https://doi.org/10.1007/s00784-024-05715-1

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