【作者】 徐敏锐；

【导师】 程辉；

【作者基本信息】 福建医科大学 ， 口腔临床医学， 2007， 硕士

【摘要】 目的研究钴铬合金铸造卡环的弹性形变限度及其抗疲劳性能,并探讨其规律性。方法采用三个不同厂家生产的钴铬合金制得30个的铸造直卡环,在万能材料试验机上进行加载-形变测试,试验机自动采集的数据经过一系列软件处理后得到卡环的弹性形变限度及相应的卡抱力。然后三种钴铬合金根据基牙外形再铸造30个卡环,分别进入0.25mm和0.50mm两种倒凹深度,并在万能材料试验机测量卡环的脱位力(测试速度为20mm/min),然后将卡环戴到金属基牙上进行循环脱戴实验360次,相当于临床上RPD卡环使用三个月,每次循环实验结束后再进行卡环脱位力的测量。此过程重复进行20次,相当于临床上RPD卡环使用5年。采用单因素方差分析、Kruskal-Wallis检验以及重复测量方差分析对实验结果进行统计处理。结果⑴三种钴铬合金铸造卡环的弹性形变限度及相应卡抱力存在显著差异,上海硬质型钴铬合金卡环的弹性形变限度及相应卡抱力均小于其余两种钴铬合金;当形变为0.25mm时,三种钴铬合金卡环的卡抱力无显著差别,当形变为0.50mm时,Vera PDSTM钴铬合金具有最大的卡抱力。⑵循环测试前后所有卡环的脱位力均出现明显下降,RegalloyTM 0.25mm组卡环脱位力下降最明显,达4.954N,脱位力变化最小的是Vera PDSTM 0.25mm组,为1.832N。两种倒凹深度的Vera PDSTM钴铬合金卡环在循环测试过程中均保持有最大的脱位力。结论⑴钴铬合金铸造卡环进入基牙倒凹的深度应以0.25mm为宜。⑵卡环的脱位力随循环次数的增加而减小,二者间呈对数形式变化。⑶在三种钴铬合金中,Vera PDSTM钴铬合金具有最佳的抗疲劳性能,在两种倒凹深度下均能满足RPD5年使用的固位力需要。更多还原

【Abstract】 Objective The aim of this study was to investigate the elastic deformation limit and the fatigue resistance of cobalt- chromium alloy cast clasps, and to probe into the rules of this variation.Methods Thirty cast straight clasps made of three types of cobalt-chromium alloys were subjected to compression-deformation test in the universal material test mechine, the elastic deformation limit and relevant enclasp forces were got after the datas produced from the mechine were analyzed by a serial of softwares. Then another 30 clasps casted by the three types of cobalt-chromium alloys were made to engage one of 2 retentive undercut depths (0.25mm or 0.50mm). The force(N) required to remove the clasps was measured using the universal testing machine with the crosshead speed of 20mm/min. After measuring the retentive force, the clasps were cycled on and off the metal abutment tooth for 360 times, simulating the insertion and removal of a removable partial denture clasp for 3 months. The cycling sequence was repeated 20 times, and the retention force was measured after each sequence, simulating the clinical usage for 5 years in total. Data were subuected to one-way analysis of variance and Kruskal-Wallis test, followed by repeated measures analysis of variance. Results⑴The elastic deformation limit of the three types of cobalt-chromium alloys and relevant enclasp forces were not all the same, the result Shanghai group was significance smaller than other 2 groups. No significance were found in enclasp forces amound 3 groups when the clasp deformation was 0.25mm, and the Vera PDSTM showed the greatest forces when the deformation reached 0.50mm.⑵All of the 3 groups experienced a significance decrease in retentive force measruements before and after the cyclic fatigue test. The greatest decrease was found in RegalloyTM 0.25mm group with the figue of 4.954N , and the smallest was found in Vera PDSTM 0.25mm group, the figue was 1.832N. The Vera PDSTM maintained the greatest retentive forces until the final cycling sequence in both undercuts. Conclusions⑴The cobalt-chromium alloy cast clasps should be designed with the best undercut of 0.25mm.⑵The retention force of cobalt-chromium alloy cast clasps experienced a gradual decrease along the cycling sequence, they assumes the logarithm changing pattern.⑶Vera PDSTM showed the best resistance to cyclic fatigue amoung the 3 types of cobalt-chromium alloys, which could maintained retention over a simulated 5-year period in both undercups.更多还原