Three-Dimensional Finite Element Analysis Of He Influence Of Implant Location And Diameter On Ress Distribution For Implant-Supported Cantilever Fixed Partial Denture Under Dynamic Load

Objective:To examine the influence of location and diameter of implants on stress distribution for implant-supported cantilever fixed partial denture (FPD) in the posterior mandibular bone.Methods:1. A mandibular specimen was chose to establish the three-dimensional (3D) finite element model including an FPD, mesial and distal implants, and supporting bone. CT scan technology, the finite element software Mimics10.01, Magics12.0and UG NX6.0were used to establish the3D finite element models.2. Stress analysis of different finite element models. The mesial implants with diameter of4.1mm or4.8mm were placed in locations where their long axis were 3.0mm to13.0mm posterior to the remaining first premolar on each model. The distal implant with a diameter of4.8mm was fixed at the same distance from the premolar on each model. Dynamic loads of250N from different directions were placed on each occlusal surface of the FPD to simulate the masticatory cycle of0.875s. The Von Mises stresses were calculated by the finite element analysis software MSC.Marc and Patran.Results:1. The3D finite element model including mandible and implant-supported fixed partial denture was created, which had good mechanical geometric similarity and can be used in medical research.2. The maximum stresses were shown in the cortical bone adjacent to the mesial or the distal implants from stage Ⅱ to Ⅳ in a masticatory cycle. The maximum Von Mises stresses of cancellous bone were concentrated at the bottom of implants, which were only30%-46%of that of compact bone.3. The maximum stresses increased as the mesial implant was located more posterior to the first premolar. A significant increase of the Von Mises stresses was found when the mesial implant was located more than8.0mm posterior to the first premolar.4. The use of wider implant reduced the stress in the interface between bone and the implants by13%-43%.5. Off-axial load induced more stresses than vertical load and created the maximum stresses in a masticatory cycle. Conclusion:1.3D FEM is a reliable way of analyzing the stress distribution of the implant-supported partial dentures. The Von Mises stresses are analyzed under dynamic load using a3D FEM, which conforms to actual conditions.2. Implant location in the cantilever FPDs is a significant factor influencing the stress created in the interface between bone and the implant. Cantilever is one of the feasible choices of implant-supported posterior FPDs when its length is no more than the width of a premolar.3. The use of wider implant can relieve the stress concentrated in the bone around the implant. The choice of diameter should consider both bone volume and the length of cantilever.