不同基牙牙周状况下双侧游离缺损冠外附着体义齿的三维有限元分析

3D Finite element analysis of bilateral distal-extension extracoronal attachment denture with different abutment periodontal quantity

目的:探讨不同基牙牙周状况下,下颌后牙双侧游离缺损冠外附着体义齿支持组织的应力分布情况。方法:建立下颌双侧67游离缺损冠外附着体义齿修复时基牙牙周健康和基牙牙周吸收的三维有限元模型,分析垂直载荷下基牙牙周状况不同时,基牙牙周组织及缺牙区牙槽嵴的VonMises应力分布。结果:与牙周健康的模型相比,当第二双尖牙牙周吸收1/3时,远中基牙牙周膜和牙槽骨的最大应力值均增加了两倍多;当第一和第二双尖牙牙周均吸收1/3时,远中基牙牙周膜和牙槽骨的最大应力值是基牙健康时的四到五倍。随着牙周吸收的基牙数目的增加,缺牙区牙嵴的最大应力值增加了47%。增加基牙数目可显著降低远中基牙的牙周组织和缺牙区牙嵴的应力,使义齿支持组织的应力分布更为均匀。结论:冠外附着体义齿修复下颌双侧后牙游离缺损时,若两侧只有第二双尖牙牙周吸收1/3时,修复设计时可考虑增加基牙数目,若第一和第二双尖牙牙周均有吸收则不建议再选作附着体义齿基牙。

Objective： To investigate the stress distribution in the bilateral distal-extension attachment denture supporting tissue with different abutment periodontal quantity. Methods： Reconstructed the three-dimensional finite element models of the extracoronal attachment denture with mandibular Kennedy I dentition defect, analyzed the stress distribution of the denture supporting tissue with Von Mises ability of sustain pressure when vertical forces were applied, compared the absorbed-periodontal abutment models with the normal-periodontal abutment models. Results： Compared to the normal-periodontal abutment models, when the second premolar periodontal tissues absorbed 1/3, the maximal pressure increased more than twice on the periodontal member and the alveolar bone of the distal-abutment; when the first and the second premolar periodontal tissues absorbed 1/3, the maximal pressure increased about 4-5 times on the periodontal member and the alveolar bone of the distal-abutment. When the number of the absorbed-periodontal abutment was increased, the maximal pressure of the alveolar bone under the denture increased 47%. When the abutment number was increased from two to three, the pressure of supporting tissues obliviously decreased. Conclusion： Restoring mandibular bilateral distal-extension edentulous dentition with extra-coronal attachment, it was necessary to increase the number of the abutment, if only one premolar periodontal tissues was absorbed 1/3; it was not advisable to restore with attachment dentures, if both premolar periodontal support tissues was absorbed.