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Stress distribution of restorations in external cervical root resorption under occlusal and traumatic loads: a finite element analysis
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Padmapriya Ramanujam, Paul Kevin Abishek Karthikeyan, Vignesh Srinivasan, Selvakarthikeyan Ulaganathan, Velmurugan Natanasabapathy, Nandini Suresh
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Restor Dent Endod 2025;50(2):e21. Published online May 21, 2025
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DOI: https://doi.org/10.5395/rde.2025.50.e21
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 Abstract
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- Objectives
This study analyzed the stress distribution in a maxillary central incisor with external cervical resorptive defect restored with different restorative materials under normal masticatory and traumatic loading conditions using finite element analysis.
Methods
Cone-beam computed tomography of an extracted intact incisor and created resorptive models (Patel’s 3D classification-2Bd and 2Bp) in the maxillary central incisor was performed for finite element models. The 2Bd models were restored either with glass ionomer cement (GIC)/Biodentine (Septodont) or a combination of both with composite resin. 2Bp models were restored externally with a combination technique and internally with root canal treatment. The other model was external restoration with GIC and internal with fiber post. Two masticatory loads were applied at 45˚ to the palatal aspect, and two traumatic loads were applied at 90˚ to the buccal aspect. Maximum von Mises stresses were calculated, and stress distribution patterns were studied.
Results
In 2Bd models, all restorative strategies decreased stress considerably, similar to the control model under all loads. In 2Bp models, the dentin component showed maximum stress at the deepest portion of the resorptive defect, which transfers into the adjacent pulp space. In 2Bp defects, a multilayered restoration externally and root canal treatment internally provides better stress distribution compared to the placement of a fiber post.
Conclusions
Increase in load, proportionally increased von Mises stress, despite the direction or angulation of the load. Multilayered restoration is preferred for 2Bd defects, and using an internal approach of root canal treatment is suggested to restore 2Bp defects.
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Pattern of endodontic instrument separation and factors affecting its retrieval: a 10-year retrospective observational study in a postgraduate institute
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Velmurugan Natanasabapathy, Aswathi Varghese, Paul Kevin Abishek Karthikeyan, Srinivasan Narasimhan
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Restor Dent Endod 2025;50(1):e7. Published online February 19, 2025
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DOI: https://doi.org/10.5395/rde.2025.50.e7
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Abstract
PDFPubReaderePub
- Objectives
This study aimed to assess the pattern of endodontic instrument separation, their retrievability, and factors affecting its retrieval, in a postgraduate institute.
Methods
Cases referred for the management of separated endodontic instruments (SEI) from 2013 to 2023 were considered for this study. Data related to demographics, tooth type, file type, and retrieval were documented in an Excel sheet. Eight prognostic factors assumed to influence the retrieval were analyzed in this study. The secondary aim was to compare the pattern of SEI and retrievability between conventional nickel-titanium files and newer generation heat-treated nickel-titanium files. Retrieval was attempted by a senior endodontist under the dental operating microscope. Various ultrasonic tips and a Broken Tool Removal loop system were used during retrieval. Simple descriptive statistics were performed. Binomial logistic regression was done to identify the effect of the eight prognostic factors on the retrieval outcome.
Results
A total of 190 SEI was reported. SEI occurred more often in posterior teeth than anterior teeth, mandibular arch than maxillary arch, and in larger files than smaller files. Separation occurred more often in the apical third compared to the other levels. Retrieval was attempted in 88 cases and successful in 70 cases (79.5%). The larger taper and apical position of the SEI negatively influenced the retrieval by 1.4 and 8.7 times, respectively.
Conclusions
Retrieval of SEI was successful in the majority of the cases. An increase in taper and apically placed SEI negatively impacted the retrieval. There was no difference in the pattern of separation nor retrievability between conventional nickel-titanium files and newer generation heat-treated nickel-titanium files.
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Citations
Citations to this article as recorded by  - Effectiveness of microscope-assisted root canal treatment in permanent posterior teeth: A retrospective cohort study
Ya-Ching Chang, Ting-Ya Wang
Journal of Dentistry.2025; 157: 105771. CrossRef
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