|
|
2022, Vol. 26 ›› Issue (16): 2540-2544Three-dimensional finite element analysis of stress distributions in osteoporosis and normal mandibular dental implant-supported overdentures with flat-type and cushion-type magnetic attachmentsLi Yuan1, Song Liang1, Zhang Jianguo2, Hu Fengling1
Abstract: BACKGROUND: Implanting magnetic overdentures use implants, magnetic attachments, and oral mucosa to provide retention, support, and stability for the denture. Therefore, implanting magnetic overdentures are particularly suitable for edentulous patients, especially those with unsatisfactory jaw conditions. OBJECTIVE: To compare the biomechanical response of normal mandible and osteoporosis mandible in two implants supported with flat-type and cushion-type magnetic attachments. METHODS: The CT data of mandible and overdenture of one patient with edentulous jaw that met the requirements were selected. A three-dimensional finite element model of a two-implant-retained mandibular overdenture with flat-type and cushion-type magnetic attachments was developed and two types of bone quality (normal and osteoporosis) were prepared. Four types of load were applied to the overdenture in each model: 100 N vertical and oblique (buccal lingual inclination 45°) loads on the right first molar and a 100 N vertical load on the right canine and the lower incisors. The maximum equivalent stresses in cortical bone and cancellous bone of the models were analyzed. RESULTS AND CONCLUSION: (1) Under the same magnetic attachment and loading force, the maximum equivalent stress in normal cortical bone and cancellous bone was greater than in osteoporotic bone. When the lower right first molar was loaded with oblique loading force, the stress value of the cortical bone around the implant was more than twice that of the vertical loading. When the loading conditions were the same, whether it was normal jaw or osteoporotic jaw, the stress value of the flat-type magnetic attachment was higher than that of the cushion-type magnetic attachment. (2) Under the same magnetic attachment and loading force, the maximum stress of the cancellous bone around the normal jaw implant was greater than that of the cancellous bone in the osteoporotic state. When the right lower first molar was inclined to the loading force, the stress value of the cancellous bone around the implant was more than twice that of the vertical load. The maximum stress of the cancellous bone around the normal jaw implant was greater than that of the cancellous bone in the osteoporotic state under the vertical force of the two magnetic attachments. When the loading conditions were the same, whether it was a normal jaw or an osteoporotic jaw, the stress value of the flat-type magnetic attachment was significantly higher than that of the cushion-type magnetic attachment. (3) The results show that in the state of osteoporosis, the low stress on the jaw bone comes from greater elastic deformation of the bone tissue, which is not conducive to osseointegration, and lateral force will cause greater stress around the implant, which is not conducive to the stability of the implant. Key words:three-dimensional finite element analysis, osteoporosis, magnetic attachments, implant, biomechanics, overdenture, stress and strain |