Three-dimensional finite element analysis of implant-supported prosthodontic designs for maxillary first molars with root fracture.

Abstract

<h4>Background</h4>This study validated a patient-specific three-dimensional (3D) finite element (FE) model utilizing cone-beam computed tomography (CBCT) scans and occlusal records from a bruxism patient exhibiting a fractured right maxillary first molar. The model analyzed lateral mandibular movements linked to fracture initiation and evaluated its clinical utility in optimizing implant-supported prosthetic designs through biomechanical stress profiling.<h4>Method</h4>Lateral mandibular movements were simulated by the FE model from patient with bruxism to pinpoint the displacements that cause fracture-related stress concentrations. Three zirconia/resin implant crowns with cusp inclinations were modeled on the fracture geometry. Simulated biomechanical stress distribution was analyzed to assess effects on peri-implant bone, fixtures, and prosthetics.<h4>Results</h4>The pre-fracture model revealed stress concentrations coinciding with clinical root fracture sites during lateral mandibular movements defined by displacement parameters (x=-0.5 mm, y=-0.2 mm, z = 0 mm). In implant-supported prostheses, increased cusp inclination elevated stress in both implants and peri-implant bone, with zirconia crowns exhibiting higher stress than resin counterparts. The prosthetic abutment showed maximal stress concentration, approaching titanium's yield strength at 30° inclination.<h4>Conclusions</h4>Three-dimensional finite element analysis (3D-FEA) effectively simulates abnormal occlusal stress directions in root-fractured teeth, proposing a novel clinical method to determine occlusal stress vectors. Additionally, for bruxism patients, implant prostheses should prioritize low cusp inclinations and use materials with low elastic modulus to mitigate stress concentration and mechanical complication risks.