下颌全口覆盖义齿的加强结构对基托下黏膜应力分布影响的三维有限元分析

目的 分析下颌全口覆盖义齿加强前后及不同的加强设计对基托下黏膜应力分布的影响.方法 采用三维有限元法,设定只有两侧尖牙残根残留的下颌牙槽嵴为实验对象,残根上形成根帽,并分别建立无加强,钢丝加强和铸造结构加强的覆盖义齿3个有限元模型,在单侧第一双尖牙区及第二磨牙区垂直加载49 N的力,对覆盖义齿基托下黏膜应力分布的情况进行分析.结果 第一双尖牙区加载时,基托下黏膜应力总和表示为按无加强、钢丝加强和铸造结构加强的顺序依次减小,与加载位置无关.与无加强和钢丝加强比较,铸造结构加强的最大应力显示为最小,且基托下应力分布更均匀和广泛.结论 使用了覆盖根帽顶点和牙槽嵴顶的加强结构加强的覆盖义齿能够有效的分散负载,使下颌覆盖义齿基托下应力分布更均匀和广泛,有利于基托下黏膜的保护.

Influence of reinforcing structure of mandibular complete overdenture on stress distribution in residual alveolar ridge using three-dimensional finite element analysis

Objective To examine the influence of reinforcing structure of mandibular complete overdenture on stress distribution in residual alveolar ridge using three-dimensional finite element analysis.Methods Three models of mandibular overdenture with different reinforcements were established:without reinforcement(BS);with chrome-cobalt reinforcing wire(BW);with reinforcing structure,reinforcement on the coping top(BB).The models contained the mandibular body with alveolar mucosa,two copings and overdenture.A vertical loading of 49 N was applied on the occlusal surface of mesial side in first premolar region(P1),buccal side(M2B),center(M2C),and lingual side(M2L) in second molar region.Results When loading was applied on P1,the sum of stress in the alveolar mucosa beneath the overdnenture was BS>BW>BB,and was not different among the three models when loading was applied on M2C.When loading was applied on M2B and M2L,the stress of BS model was slightly greater than those of BW and BB models.Conclusion The reinforcement adjacent to the top of the coping and the residual alveolar ridge could reduce the stress beneath the dentures,and is helpful in making the distribution of the stress of residual alveolar ridge more widely and evenly.