The Biomechanical Properties Of The Complete Mandibular Subperiosteal Implant

As the proportion of old people is rising in our country, more and more peopleneed a complete denture to maintain their masticatory function and pronunciationwhen they lose all the tooth. Some patients’ mandibular alveolar bone has advancedatrophy that causes the poor stability and occlusive of the complete denture, and theendosteal implant is contraindicated in these patients duo to poor posterior ridgeanatomy. The complete mandibular subperiosteal implant can help stabilize thecomplete denture and unlike the endosteal implant, the complete mandibularsubperiosteal implant is indicated in patients with advanced atrophy of mandibleleaving in place the more stable basal bone with special anatomical contours.Although the complete mandibular subperiosteal implant has these advantages, theduplication of the mandibular bony surface needs to expose the mandibular bone. Inorder to solve this problem, this paper introduced a new way using the CT data tomodel the subperiosteal implant. At the same time, the finite element analysis is usedto explore how the implant works with the mandibular. The influence of the posts’number and distance, the loads’ location and direction is considered. Some advices aregiven to improve the modality of the implant, and the results of the FEA analysis canprovide doctors some references in clinical.The way to model the subperiosteal implant is based on the spiral CT data ofpatients. Importing the CT data to the interactive medical image control systemMIMICS to calculate the mandibular’s3D triangular patches model. For the reasonthat the3D triangular patches model’s surface cannot be shelled, the reversingengineering software Geomagic Studio is used to establish the3D NURBS facesmodel. This surface of the model is cut to the contour of the implant basis with thehelp of the computer aided software SolidWorks. The implant’s basis is established byshelling the cut surface. The posts and bars are also established. This new way tomodel the subperiosteal implant can be used to process the subperiosteal implant inclinical. The advantage of this way is that we don’t have to expose the mandibularbone to make the duplication of the mandibular bony surface.The finite element analysis is used to explore how the implant works with themandibular. The finite element analysis software ANSYS Workbench offers a staticstructure module for us to analysis the implant-mandibular model. The results containthe stress and the displacement distribution of the implant and the mandibular, thepressure stress and the frictional stress distribution on the contact surface of the implantand the mandibular, and the the contact surface of the compact bone and thecancellous bone.This study is a multi-disciplinary issue, and the basic anatomic, medical,computational solid mechanics, biomechanics knowledge is required. The way todesign the subperiosteal implant is described. Some pieces of advice are provided toadvance the modality of the implant and the clinical treatment.