Three-Dimensional Finite Element Analysis of Fixed Complete-Arch Prostheses Supported by 4 Immediate-Loaded Implants in the Completely Edentulous Maxilla Using Clinical Computerized Tomography Data

摘要

Mechanical simulation by loading an occlusal force (load), assumed to be that loaded under clinical conditions, was performed in a computerized tomography (CT) data-based immediate-loaded implant placement simulation. Stresses on and displacements of the implants and surrounding bone tissue were analyzed mechanically using 3-dimensional finite element analysis (FEA). The purpose of this study was to investigate the possibility of practical preoperative design and its evaluation and to assess the effects of connected fixation. Implants with a diameter of 4.0 mm were placed in the bilateral upper incisor and second premolar regions in a 69-year-old woman. An X-ray CT of the head was carried out, and implant placement simulation and 3-dimensional FEA models were constructed from the CT data. Forces were loaded on 4 individual implants placed in this model or all connected implants, and a mechanical analysis was performed. A 100-N vertical force was loaded on each implant as individual loading for the control group, and a 400-N vertical force was loaded on the connected implants as connected loading for the test group. The displacement and stress distributions were assessed using the 3-dimensional FEA. In the test group, established on the assumption of connected fixation for provisional restoration facilitating immediate loading, the maximum stress and displacement of peri-implant bone were smaller than those in the control group undergoing individual loading. The implant displacement level was suggested to serve as a numerical prognostic index of osseointegration of immediate-loaded implants. This method was shown to be immediately applicable to implant placement simulations using CT data currently generated in clinical practice, with no modification. Such a mechanical assessment using the FEA model can be performed noninvasively.