有限元模拟牙周膜组织、牙齿振动频率和牙的动度的关系

目的:分析动态有限元模型中正常前牙牙周附着水平与其固有振动频率和牙齿动度的关系,以及承担咬合力后受力状况,为定量描述牙周附着水平和牙齿动度等牙周组织的生理状况提供理论依据。方法:在上颌前牙三维结构基础上,构建反映牙周附着水平和牙周组织弹性特征的动态三维有限元模型,对牙周附着水平、牙齿固有振动频率和牙齿动度的相互关系以及咬合力作用下应力传递过程进行动力学分析。结果:牙周健康上颌前牙振动是由多阶振动所构成,前四阶振动是其主要的振动形式,振动频率为1516.32、1761.44、2214.82、3243.98Hz,牙齿不同方向的动度与牙齿在该方向的振动频率与振型相关。结论:牙齿的动度可通过不同方向的振动频率及其振型定量表达,结合牙齿的动度、牙周附着水平和牙周组织力学特征进行动力学分析,能准确描述出牙齿和牙周组织的生理状况以及在行使功能过程中的生物学效应。     

Retained "hopeless" teeth. Effects on the proximal periodontium of adjacent teeth

The retention of teeth diagnosed as periodontally "hopeless" may accelerate the destruction of the adjacent proximal periodontium. Studies determining the influence these teeth have on the health status of adjacent teeth appear nonexistent. It was the intent of this retrospective study to assess the status of the periodontium in adjacent teeth proximal to the periodontium of "hopeless" teeth. We evaluated 17 teeth, each being mesially adjacent to one "hopeless" tooth, in 17 subjects treated for periodontal disease. In each case, the "hopeless" and the adjacent teeth received the same treatment. Probing depths (P-D), radiographic alveolar bone level (R-BL) and the width of the periodontal ligament space (W-PL) were measured for both the adjacent interproximal and the nonadjacent interproximal surface for each hopeless tooth. At both pretherapy and posttherapy, there were no significant differences for any of the variables (P-D, R-BL and W-PL) for the adjacent interproximal surfaces with the nonadjacent interproximal surfaces. However, there was a significant reduction in the mean probing depth for the adjacent interproximal surfaces, pretherapy to posttherapy. No other significant changes were found in any of the other variables for either the adjacent or nonadjacent interproximal surfaces. These data suggest that teeth considered periodontally "hopeless" and retained have no effect on the proximal periodontium of adjacent teeth prior to and following therapy.     

The condition of the periodontium in patients with clefts]

41 patients with total clefts, having an average age of 14.6 years, were examined. In these patients, the bone index was determined by means of the radiographic method of Schei et al. (as modified by Engelberger, Rateitschat and Marthaler). Furthermore, the teeth were tested for mobility, and the gingival retraction and the pocket depth were measured. The degree of gingival inflammation was scored using the PMA index according to Mühlemann and Mazor. The findings from the cleft quadrants were compared to those from the non-cleft quadrants of the upper jaw and to those from the mandibular quadrants.     

光敏树脂美容修复对牙周组织的影响

目的：观察光敏树脂修复后对牙周组织健康的影响。方法：对30例475个牙齿作贴面美容修复，术前记录牙齿的牙周指数，与术后3月、半年复查结果进行对照分析。结果：牙周三项指数术前与术后3月，半年比较均存在差异。结论：作牙齿贴面美容修复后，必须定期作牙周组织健康护理，才能维持牙周组织的健康，保持牙齿美容。     

前牙牙周附着水平与牙齿振动频率的有限元分析

目的：采用动态有限元法分析前牙牙周附着水平与牙齿固有振动频率和动度的关系，为定量描述牙周附着水平和牙齿动度等牙周组织的生理状况提供理论依据。方法：在上前牙三维结构基础上，构建反映牙周附着水平和牙周组织弹性特征的动态三维有限元模型，对牙周附着水平、牙齿固有振动频率和牙齿动度的相互关系进行动力学分析。结果：前牙振动是由多阶振动所构成，前4阶振动为主要的振动形式，与临床牙齿动度方向一致。随着牙槽骨的吸收和牙周附着水平的降低，前4阶振动频率逐渐降低。牙齿不同方向的动度与牙齿在该方向的振动频率与振型相关。结论：牙周附着水平与振动频率有明确的相关关系，通过牙齿振动频率的变化可以表达出牙周附着水平的变化，并且与牙齿动度建立相关关系，牙齿动度可以通过不同方向的振动频率和振型定量表达。