Influence of block-out on retentive force of thermoplastic resin clasps: an <i>in vitro</i> experimental and finite element analysis
Influence of block-out on retentive force of thermoplastic resin clasps: an <i>in vitro</i> experimental and finite element analysis
复制标题
封闭对热塑性树脂卡扣保持力的影响：<i>体外</i>实验和有限元分析
DOI：
10.1016/j.jpor.2019.01.002
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发表时间：
2019
影响因子：
3.6
通讯作者：
Wakabayashi Noriyuki
中科院分区：
文献类型：
--
作者：
Yamazaki Toshiki;Murakami Natsuko;Suzuki Shizuka;Handa Kazuyuki;Yatabe Masaru;Takahashi Hidekazu;Wakabayashi Noriyuki
目的：本研究的目的是确定用于消除下切区域的封堵制剂对树脂卡环固位力和应力分布的影响。方法：在前磨牙基牙冠上制作72个聚酯和聚酰胺树脂卡环。在基牙上使用两种垂直嵌体和三种水平嵌体（缺失侧）的组合。每个卡环使用万能试验机进行体外去除试验。记录卡环在基牙上的固位力和痕迹，采用单因素方差分析和事后比较分析（α= 0.05）。对树脂卡环的应力分布进行了非线性有限元分析。结果：树脂卡环的垂直挡块长度为0.75 mm，其固位力明显高于0.5 mm。有水平挡块的树脂卡扣的固位力明显低于无水平挡块的树脂卡扣。两种热塑性树脂间无显著差异。在有限元分析中，树脂搭扣的最大第一主应力集中在搭扣肩下，受水平挡块宽度的影响较大。结论：体外实验表明，即使是0.5 mm的凹痕，水平封堵也是必要的。树脂搭扣的设计应从固位力和变形风险两方面考虑。
Purpose: The purpose of this study was to determine the effect of block-out preparation, used to eliminate the undercut area, on the retentive force and stress distribution of resin clasps.Methods: A total of 72 polyester and polyamide resin clasps were fabricated on a premolar abutment crown following six block-out preparations. A combination of two types of vertical block-outs and three types of horizontal block-outs (on the missing side) was used on the abutment tooth. Each clasp was subjected to an in vitro removal test using a universal testing machine. The retentive force and traces of the clasp on the abutment tooth were recorded and analyzed with one-way analysis of variance and post hoc comparisons (α= 0.05). Non-linear finite element analysis was performed to assess the stress distributions of the resin clasps.Results: Resin clasps with a vertical block-out of 0.75 mm undercut showed significantly higher retentive force than those with the 0.5 mm undercut. Resin clasps with horizontal block-out showed significantly lower retentive force than those without horizontal block-out. There was no significant difference between the two thermoplastic resins. The maximum first principal stress of the resin clasp was concentrated under the shoulder of the clasp and strongly influenced by the width of horizontal block-out in the finite element analysis.Conclusions: This in vitro experiment suggested that a horizontal block-out is necessary even for a 0.5-mm undercut. The design of the resin clasp should be considered from two aspects: retentive force and deformation risk.