The influence of post length and crown ferrule length on the resistance to cyclic loading of bovine teeth with prefabricated titanium posts.
The influence of post length and crown ferrule length on the resistance to cyclic loading of bovine teeth with prefabricated titanium posts.
复制标题
桩长度和冠套圈长度对预制钛桩牛牙抗循环载荷的影响。
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Gert Ravnholt
中科院分区：
文献类型：
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作者：
F. Isidor;'. Odont;Knud Brendum;Gert Ravnholt
目的
本研究的目的是评价桩和套圈长度对预制钛桩(ParaPost)和牙冠抗循环(疲劳)载荷的影响。
材料和方法
将90颗大小相近的牛牙固定在含人造硅胶牙周韧带的亚克力牙块中。桩长度为5 mm、7.5 mm和10 mm，套圈长度(即牙冠的垂直牙本质重叠)为0 mm、1.25 mm和2.5 mm的组合组成了9个不同的组，每个组包括10个牙齿。桩用磷酸锌粘固剂粘接。制作复合树脂核，粘结全冠。每个试件承受400N的循环载荷，频率为每秒1次载荷，与牙齿长轴成45度角。
结果
除2个标本外，其余标本均因牙根折断而失败；在其余2个标本中，核固位丧失。观察到不同组之间的结果有很大的差异。对自然顺序组的非参数双向分析显示，随着套圈长度的增加，抗循环载荷的断裂阻力显著增加(P<；0.01)，而桩长度的增加并没有增加断裂阻力(P=0.44)。
结论
套圈长度比桩长度在增加冠牙对循环载荷的抗折能力方面更为重要。
PURPOSE
The purpose of this in vitro study was to evaluate the influence of post and ferrule length on the resistance to cyclic (fatigue) loading of teeth with prefabricated titanium posts (ParaPost) and crowns.
MATERIALS AND METHODS
Ninety bovine teeth with similar dimensions were mounted in acrylic blocks with artificial silicone periodontal ligaments. Combinations of post lengths of 5 mm, 7.5 mm, and 10 mm, and ferrule lengths (i.e., the vertical dentinal overlap of the crown) of 0 mm, 1.25 mm, and 2.5 mm made up 9 different groups consisting of 10 teeth each. The posts were cemented with zinc phosphate cement. Composite-resin cores were made and crowns were cemented. Each test specimen underwent cyclic loading of 400 N with a frequency of 1 load per second at an angulation of 45 degrees to the long axis of the tooth.
RESULTS
All but 2 specimens failed with a root fracture; in the remaining 2 specimens the core lost retention. A large variation in the results between the various groups was observed. A nonparametric 2-way analysis for groups with a natural order revealed that the fracture resistance to cyclic loading increased statistically significantly with increasing ferrule length (P < 0.01), whereas increasing post length did not increase fracture resistance (P = 0.44).
CONCLUSION
Ferrule length was more important than post length in increasing fracture resistance to cyclic loading of crowned teeth.