下颌KennedyⅡ类牙列缺损冠外附着体义齿基牙牙周状况对支持组织应力分布的影响

目的探讨不同基牙牙周状况下,下颌后牙单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KennedyⅡ类牙列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von Mises应力分布。结果基牙数目相同的条件下,与牙周健康的模型相比,牙周吸收的模型第二前磨牙的最大应力升高了约30%,牙周最大应力升高了约10%,缺牙区牙嵴的最大应力升高了36%和14%。对于牙周吸收的模型,基牙数目从两颗增加到三颗时,义齿支持组织的应力值无明显降低。结论在下颌单侧游离缺损修复中,末端基牙牙周部分吸收1/3即可导致基牙牙周组织及缺牙区牙嵴的应力明显增加,增加基牙数目并不能有效地降低义齿支持组织的最大应力值。

Influence of abutment periodontal quantity on stress distribution in supporting tissue on extracoronal attachment denture with unilateral distal-extension prosthesis

Objective To investigate the stress distribution in the unilateral distal-extension attachment denture supporting tissue with different abutment periodontal quantities. Methods We reconstructed the three-dimensional finite element models of the extracoronal attachment denture with mandibular Kennedy Ⅱ dentition defect, analyzed the stress distribution of the denture supporting tissue with yon Mises ability of sustain pressure when vertical forces were applied, and compared the absorbed- periodontal abutment models with the normal-periodontal abutment models. Results Compared with the normal-periodontal abutment models, on the absorbed- periodontal abutment models, the maximal pressure increased by about 30% on the abutments ,about 10% on the periodontal tissues ,about 36% and 14% on the alveolar bone under the denture; when the abutment number was increased from two to three,the pressure of supporting tissues did not obviously decrease. Conclusion When the distant-abutment periodontal tissues were absorbed by 1/3 ,the pressure on the abutments periodontal tissues and the alveolar bone under the denture was obviously enlarged, and increasing the abutment number couldn＇t effectively decrease the pressure of supporting tissues.