Finite Element Analysis of Endodontically Treated Mandibular Second Molars With Variable Root Morphologies: Endocrown vs. Post-And-Core Crown Restorations.

This study aimed to investigate the biomechanical impact of root canal anatomical variations and restoration techniques on endodontically treated mandibular second molars using finite element analysis. Five root morphologies were modelled: separated-rooted (S), fused-rooted with V-shaped (F-V), U-shaped (F-U) or Ω-shaped (F-Ω) radicular grooves and single-canal fused-rooted (F-O). Micro-CT scans were performed before and after endodontic instrumentation to generate the finite element models: intact teeth, post-and-core crowns with 2- to 3-mm ferrules and endocrowns with 3- to 4-mm pulp chamber extensions. Under axial/oblique loading, von Mises stress distribution was evaluated. Results showed endocrowns had lower peak stresses than post-and-core crowns in common anatomical variations (S, F-U, F-Ω); F-V showed comparable peak stresses; post-and-core crowns with sufficient ferrule height minimised oblique-load stresses in single-canal teeth (F-O). Pronounced stress concentrations were observed at Ω-shaped groove in post-and-core restored teeth. Comprehensive evaluation of root morphology is critical for optimal restoration planning.