Purpose: To evaluate the biomechanical behaviors of multiple implant-supported prostheses with different implant lengths, connections, locations, and restoration materials in the maxillary anterior region using three-dimensional finite element analysis.
Materials and methods: A finite element model of a maxillary image was created from a tomography data bank. The simulations were executed in two types of models based on the treatment plan: (1) two implants with 4.0-mm diameters placed in the maxillary central incisors to simulate an implant-supported fixed prosthesis with four elements with a cantilever of both maxillary lateral incisors; (2) two implants with 3.75-mm diameters placed in the maxillary lateral incisors to simulate a conventional fixed prosthesis with four elements with pontics for maxillary central incisors. Subsequently, the models created were subdivided into eight subgroups according to implant length, connection type, and restoration material. A total static oblique load of 150 N was applied to the cingulum area of the palatal surfaces of the four incisors at an angle of 45 degrees to the long axis of the implant in the palatal-labial direction. Bone stresses were analyzed through maximum and minimum principal stresses and ductile material as implant, framework, and abutments were analyzed using von Mises stress criterion.
Results: Regardless of implant diameter and type of treatment, the 8.5-mm-long implants exhibited the lowest tensile and compressive stresses. Maximum and minimum principal stresses were identified in the cortical bone. The lowest von Mises equivalent stress values were identified in the metal-ceramic prostheses, with the exception of the cantilever prosthesis model with flat top connection. Conical cone implant models exhibited maximum von Mises equivalent stress in contact with the abutment.
Conclusion: The lowest principal stresses in the peri-implant bone were observed in implants with conical cone connection and 8.5 mm in length. Also, in most cases, the models with metal-ceramic restorations exhibited better stress distributions.