The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a to...The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.展开更多
为了探究不同长度的玄武岩纤维(BF)共同作用时对磷建筑石膏基复合材料(PBGCM)的影响,在磷建筑石膏中加入不同长度的混杂BF,得到混杂纤维增强PBGCM。通过正交试验,从直观分析、极差分析、方差分析对其力学性能和工作性能及不同纤维长度...为了探究不同长度的玄武岩纤维(BF)共同作用时对磷建筑石膏基复合材料(PBGCM)的影响,在磷建筑石膏中加入不同长度的混杂BF,得到混杂纤维增强PBGCM。通过正交试验,从直观分析、极差分析、方差分析对其力学性能和工作性能及不同纤维长度的协同作用机理进行了研究。结果表明:3 mm和15 mm BF混掺对PBGCM的力学性能增强效果往往比3 mm和15 mm BF单掺更好;PBGCM的最大绝干抗压强度、绝干抗拉强度、绝干抗折强度分别比未掺纤维的磷建筑石膏高50.10%、122.15%、79.43%;3 mm和15 mm BF混掺对PBGCM的工作性能减弱效果小于15 mm BF单独加入。3 mm BF对PBGCM的力学性能和工作性能都有极显著的影响;15 mm BF除对其绝干抗压强度没有显著影响外,对其他性能均产生极显著的影响,且影响效果比3 mm BF更大。展开更多
To improve the utilization efficiency of water the laying length of porous tubes was analyzed. Considering long porous tubes the irrigation uniformity of porous tubes was studied by analyzing the deviation rate of the...To improve the utilization efficiency of water the laying length of porous tubes was analyzed. Considering long porous tubes the irrigation uniformity of porous tubes was studied by analyzing the deviation rate of the working head of porous tubes and through an impact analysis of the deviation ratio of flow rate based on laying length slope pressure head and perforation spacing. Results showed that the deviation ratio of the flow rate could be reduced by decreasing the length of tubes and increasing the slope. The deviation ratio of flow rate was less influenced by pressure head and perforation spacing. A best laid slope resulted in a longer laying length of the porous tubes and they were not constant.展开更多
Based on the character of the internal force distribution of the statically indeterminate truss, the elements stresses were changed by adjusting the length of bars to increase load capacity of structure. The efficienc...Based on the character of the internal force distribution of the statically indeterminate truss, the elements stresses were changed by adjusting the length of bars to increase load capacity of structure. The efficiency of the method is illustrated by several examples.展开更多
基金supported by State Key Laboratory of Oral Diseases and Department of Endodontics and Operative Dentistry, West China School of Stomatology, Sichuan Universitysupported by the Key Clinical Program of the Ministry of Health of China (2010)National Key Clinical Program of China (2010)
文摘The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.
文摘为了探究不同长度的玄武岩纤维(BF)共同作用时对磷建筑石膏基复合材料(PBGCM)的影响,在磷建筑石膏中加入不同长度的混杂BF,得到混杂纤维增强PBGCM。通过正交试验,从直观分析、极差分析、方差分析对其力学性能和工作性能及不同纤维长度的协同作用机理进行了研究。结果表明:3 mm和15 mm BF混掺对PBGCM的力学性能增强效果往往比3 mm和15 mm BF单掺更好;PBGCM的最大绝干抗压强度、绝干抗拉强度、绝干抗折强度分别比未掺纤维的磷建筑石膏高50.10%、122.15%、79.43%;3 mm和15 mm BF混掺对PBGCM的工作性能减弱效果小于15 mm BF单独加入。3 mm BF对PBGCM的力学性能和工作性能都有极显著的影响;15 mm BF除对其绝干抗压强度没有显著影响外,对其他性能均产生极显著的影响,且影响效果比3 mm BF更大。
基金Sponsored by the National Natural Science Foundation of China(Grant Nos.11362019 and 11562018)
文摘To improve the utilization efficiency of water the laying length of porous tubes was analyzed. Considering long porous tubes the irrigation uniformity of porous tubes was studied by analyzing the deviation rate of the working head of porous tubes and through an impact analysis of the deviation ratio of flow rate based on laying length slope pressure head and perforation spacing. Results showed that the deviation ratio of the flow rate could be reduced by decreasing the length of tubes and increasing the slope. The deviation ratio of flow rate was less influenced by pressure head and perforation spacing. A best laid slope resulted in a longer laying length of the porous tubes and they were not constant.
文摘Based on the character of the internal force distribution of the statically indeterminate truss, the elements stresses were changed by adjusting the length of bars to increase load capacity of structure. The efficiency of the method is illustrated by several examples.
