ABSTRACT
From alveolar bone and the complete dentition CT images, a three-dimensionalysis of nonlinear finite element model of mandibular unilateral distal-extension with extracoronal precision attachment was established. The contact elements were used between the denture and alveolar bone. The result shows that, the stress in the second premolar and periodontal tissue decreased obviously as the second abutment was added. However, the stress difference was unapparent as the third abutment was added. Considering various facts, the attachment with two abutments was suggested to be used. With the decrease of the periodontal tissue, the stress in the periodontal tissue increased, however the stress in the tooth changed slightly. Thestress in the periodontal tissue decreased effectively when the third abutment was added, as the tooth root was absorbed by 50%. In this situation, the extracoronal precision attachment can also be used.