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在磨牙远中游离缺失时,修复方式有局部可摘义齿(RPD)和种植义齿,也可选择悬臂固定义齿(FPDs)。临床曾报道带远中悬臂桥体的FDDs远期疗效成功,但也有人认为FPDs在咀嚼时产生的杠杆作用会对FPD本身及基牙和支持组织造成损伤。本研究建立了二维有限元模型,改变骨支持程度,夹板固定基牙的数目及桥体长度来模拟不同情况的FPDs,以分析其机械生物学表现。 材料及方法 建立1个代表下颌后牙区片段,包括尖牙、前磨牙及支持组织的二维有限元模型。先采用平行技术拍摄口内的标准X线照片,要求包括1个牙周健康的下颌前磨牙区和1个三单位悬臂FPD。照片进行计算机处理,对每种材料的轮廓进行扫描并建立基本模型,在基本模型基础上改变以下条件:①改变骨支持量:冠根比为1∶1.7和1∶0.5分别代表高、低水平骨支持;②改变基牙数目:单、双及3个夹板式基牙;
In the absence of distal molars, the repair methods are partial removable dentures (RPD) and implant dentures, can also choose cantilever fixed dentures (FPDs). Long-term efficacy of FDDs with distal mid-cantilever bridges has been reported clinically. However, it has also been suggested that the leveraging of FPDs during chewing may cause damage to the FPD itself and the abutments and supporting tissues. This study established a two-dimensional finite element model to change the degree of bone support, splint fixation abutment number and bridge length to simulate FPDs in different situations to analyze the mechanical biological performance. MATERIALS AND METHODS A two-dimensional finite element model representing the canine posterior tooth segment, including the canine, premolars and supporting tissues, was established. The first use of parallel technology to take standard oral radiographs, including a periodontal health mandibular premolars and a three-unit cantilever FPD. Photographs were processed by computer. The outline of each material was scanned and the basic model was established. The following conditions were changed on the basis of the basic model: ① Change in the amount of bone support: crown-root ratio of 1: 1.7 and 1: 0.5 respectively represent high and low level Bone support; ② change the number of abutments: single, double and three splint abutments;