Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide sc...Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups： control group （group A） was given 2.5% NaOC1, and 4 experimental groups were given 2.5% NaOC1 and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning elec- tron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A （P〉0.05）. In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups （P〉0.05）, but there was significant difference in removal of smear layer between group C and group B （P〈0.05）. Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D （P〈0.01）. There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOC1 could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.展开更多
背景:利用三维有限元法的变分原理和加权技术,可将具有复杂形态结构的人类牙齿模型化,有利于了解动态过程中牙体硬组织和修复体的应力分布。目的:综合分析近年来口腔领域的国内外学者对修复体生物力学的三维有限元研究状况,特别是金属...背景:利用三维有限元法的变分原理和加权技术,可将具有复杂形态结构的人类牙齿模型化,有利于了解动态过程中牙体硬组织和修复体的应力分布。目的:综合分析近年来口腔领域的国内外学者对修复体生物力学的三维有限元研究状况,特别是金属基底冠、瓷层厚度、根管预备及充填对牙体应力变化的影响。方法:由第一作者应用计算机检索1993年4月至2012年9月PubMed数据库及2001至2008年中文期刊全文数据库、维普数据库有关三维有限元法分析金属基底冠、瓷层厚度、根管预备及充填方式对牙体应力变化影响的文章,英文检索词为"porcelain-fused-to-metal,finite element method,stress analysis,root canal",中文检索词为"烤瓷熔附金属全冠,三维有限元法,应力分析,根管"。排除重复性研究及Meta分析,共保留40篇文献进行综合分析。结果与结论:三维有限元法在口腔医学中对建立高真实度和精确度的模型有着重要的意义,因此对牙体的根管治疗和治疗后修复提供了有效的生物力学信息。有关牙体与修复体在应对咀嚼作用时的应力分布在不断地探索与研究。文章总结了口腔领域国内外学者利用有限元法分析桩核冠修复体的应力变化,为将来进一步的研究提供了参考和借鉴。结果显示,三维有限元法能够建立具有非线性,各向异性等生物力学特征的三维有限元模型,能够逐渐完善其从静态分析到动态分析的转变,以真正达到精确模拟口腔生物学形态及牙齿咀嚼功能的目的。展开更多
基金supported by the Fundamental Research Funds for the Central Universities,China(No.2010JC030)
文摘Summary： This study was aimed to evaluate the effectiveness of solution form of 17% ethylenediaminetetraacetic acid （EDTA） on removing smear layer of root canals at different exposure time periods and to provide scientific basis for EDTA as a choice of root canal irrigation in clinical practice. Twenty-five single-rooted teeth were randomly divided into 5 groups： control group （group A） was given 2.5% NaOC1, and 4 experimental groups were given 2.5% NaOC1 and 17% EDTA, including groups B, C, D and E with exposure time of 1, 3, 5 and 7 min, respectively. After preparation of the root canals, the teeth were split along their longitudinal axis, and the root sections were examined under scanning elec- tron microscope for evaluation of smear layer removal and erosion on the surface of the root canal walls. The specimens in group B showed presence of smear layer on the walls of the root canal with no statistical difference from that in group A （P〉0.05）. In groups C and D, partial removal of smear layer was obtained, and there was no significant difference between the two groups （P〉0.05）, but there was significant difference in removal of smear layer between group C and group B （P〈0.05）. Root canal walls in group E specimens showed almost complete removal of smear layer, and the removal of smear layer was significantly different from that in group D （P〈0.01）. There was no significant change in the structure of the surface of root canal for each sample. It was concluded that combined irrigation with 17% EDTA and 2.5% NaOC1 could remove the smear layer with no significant alteration in dentinal structure when the chelating agent was applied for 7 min. At 3 and 5 min of application, partial removal of smear layer was observed and at 1 min negligible removal of smear layer was achieved.
文摘背景:利用三维有限元法的变分原理和加权技术,可将具有复杂形态结构的人类牙齿模型化,有利于了解动态过程中牙体硬组织和修复体的应力分布。目的:综合分析近年来口腔领域的国内外学者对修复体生物力学的三维有限元研究状况,特别是金属基底冠、瓷层厚度、根管预备及充填对牙体应力变化的影响。方法:由第一作者应用计算机检索1993年4月至2012年9月PubMed数据库及2001至2008年中文期刊全文数据库、维普数据库有关三维有限元法分析金属基底冠、瓷层厚度、根管预备及充填方式对牙体应力变化影响的文章,英文检索词为"porcelain-fused-to-metal,finite element method,stress analysis,root canal",中文检索词为"烤瓷熔附金属全冠,三维有限元法,应力分析,根管"。排除重复性研究及Meta分析,共保留40篇文献进行综合分析。结果与结论:三维有限元法在口腔医学中对建立高真实度和精确度的模型有着重要的意义,因此对牙体的根管治疗和治疗后修复提供了有效的生物力学信息。有关牙体与修复体在应对咀嚼作用时的应力分布在不断地探索与研究。文章总结了口腔领域国内外学者利用有限元法分析桩核冠修复体的应力变化,为将来进一步的研究提供了参考和借鉴。结果显示,三维有限元法能够建立具有非线性,各向异性等生物力学特征的三维有限元模型,能够逐渐完善其从静态分析到动态分析的转变,以真正达到精确模拟口腔生物学形态及牙齿咀嚼功能的目的。
