Stress Distribution in Peri-implant Bone of Implants Restored with Screw, Cement, and Cement-Screw Retained Crowns Using Three Crown Materials: a Three-dimensional Finite Element Analysis

AimTo comparatively evaluate stress distribution in the peri-implant bone in three-dimensional finite element (3D FE) models of titanium implants with different crowns-Metal Ceramic, Zirconia, Poly Ether Ether Ketone (PEEK) retained by three methods-screw, cement, cement-screw under functional load.Settings and DesignAn implant crown can be retained by screw, cement or a combination of the two-cement-screw. Materials for fabricating implant restorations vary which distribute stress differently in the peri-implant bone.Materials and MethodsNine 3D FE models depicting the restoration-implant-bone complex in the mandibular premolar region were constructed using CAD Solidworks software. The Altair pre-processor was used for model meshing. Young's modulus and Poisson's ratio were allotted to each material. Occlusal loading (100N) in vertical and oblique (30 degrees) directions was performed on the 3D FE models and von Mises stresses generated in the peri-implant bone were visualised, evaluated according to colour code, numerically recorded, assessed and compared.ResultsFor the vertical and inclined force models, stress distribution in peri-implant bone was higher in all screw retained models and lower for all cement retained and cement-screw retained models. Peri-implant bone stresses were comparable for cement retained and cement-screw retained prosthesis.ConclusionAny of the nine combinations of crown materials-Metal Ceramic, Zirconia, PEEK and retention methods-screw retained, cement retained, cement-screw retained can be used clinically as they have stress varying for less than 10% across all models.