Assessment of the Stress Distribution in Internal Resorption Cavities Filled with MTA and Biodentine in Mature Teeth: A Finite Element Analysis Study

Introduction: Internal Root Resorption (IRR) is the gradual deterioration of dentine due to clastic activity, typically appearing as a radiolucent area in the radicular dentine in communication with the root canal. Bioceramic materials such as Mineral Trioxide Aggregate (MTA) and Biodentine are available to restore the resorption cavity, offering biocompatibility and better sealing to the dentine. The present study employs the Finite Element Analysis (FEA) method to simulate stress behaviour, providing valuable insights into the effectiveness of these materials in reducing stress concentrations and reinforcing structurally compromised teeth. The findings aim to support clinical decision-making for achieving long-term restoration success. Aim: To evaluate and compare the stress distribution patterns in tooth models with IRR restored with MTA and Biodentine at the apical, middle and coronal thirds, employing FEA. Materials and Methods: This FEA study was conducted in the Conservative Dentistry and Endodontics department at Sibar Institute of Dental Sciences in Guntur, Andhra Pradesh, India, from June 2024 to August 2024. Seven three-dimensional (3D) FEA models of mandibular first premolars were designed: M1 (IRR at apical third restored with MTA), M2 (IRR at middle third restored with MTA), M3 (IRR at cervical third restored with MTA), M4 (IRR at apical third restored with Biodentine), M5 (IRR at middle third restored with Biodentine), M6 (IRR at cervical third restored with Biodentine) and M7 (control model). A force of 300 N was applied to the buccal side at a 30° inclined angle to the occlusal plane. Linear analysis was conducted to assess the Von Mises stress values along the central XY plane of the tooth model. The maximum and minimum Von Mises stresses were recorded and directly compared for each virtual tooth model. Results: Stress analysis showed maximum stress concentrations near the edges of the resorption cavities for both materials. In MTA-filled models, peak stress values were 73.35 MPa (apical), 104.35 MPa (middle) and 102.79 MPa (coronal), while Biodentinefilled models showed slightly lower peaks at 72.33 MPa (apical), 103.65 MPa (middle) and 101.86 MPa (coronal). Minimum stress values ranged from 0.0002 MPa to 0.0022 MPa across models, primarily in regions distant from the cavities. Conclusion: Biodentine exhibited slightly better stress redistribution than MTA, with lower peak stress values across all resorption levels; however, both materials left the cavity edges as critical stress concentration zones. These findings emphasise the need for additional restorative measures to address structural vulnerabilities.