Failure Probability of Three Designs of Zirconia Crowns.
Failure Probability of Three Designs of Zirconia Crowns.
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氧化锆牙冠的三种设计的失败概率。
DOI：
10.11607/prd.2448
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
MarquesdeMelo,Renata
中科院分区：
文献类型：
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作者：
Ramos,GabrielaFreitas;Monteiro,EvelynBarbosa;Bottino,MarcoAntonio;Zhang,Yu;MarquesdeMelo,Renata
目的采用双参数威布尔分析法对氧化锆全瓷或部分瓷/釉贴面全冠疲劳寿命进行评价。方法选择60颗第一磨牙，分别采用传统氧化锆支架全冠、改良全冠和整体氧化锆全冠3种不同的全冠设计（n = 20）。所有样品均用釉层处理。使用半球形尖端活塞（直径=6 mm）对样本进行机械循环（100 N，3 Hz），直至样本失效或达到2×106次循环。每隔500，000次循环，中断疲劳测试，并使用立体显微镜（10 X）检查样本是否损坏。我们对区间数据进行了威布尔分析，以计算每个区间的故障数。结果失败的类型和数量按组依次为：传统型13例，改良型6例，瓷体开裂4例，瓷体脱落4例，瓷体/核界面分层1例，粘结界面脱粘2例。Weibull参数（β，尺度; eta，形状），双侧置信区间为95%，为：传统型-1.25和0.9 × 106次循环;改良型-0.58和11.7 × 106次循环;整体型-1.05和16.5 × 106次循环。传统牙冠表现出更大的疲劳敏感性，改良组表现出更高的早期失效倾向，而整体式牙冠组表现出不敏感的疲劳。改良组和整体式组在疲劳测试后无失效的牙冠数量最多。结论3种全冠设计在疲劳载荷下表现出明显的差异。改良组和整体式组在2× 106次循环后的失效概率较小。
Objectives This study utilized a 2-parameter Weibull analysis for evaluation of lifetime of fully or partially porcelain-/glaze-veneered zirconia crowns after fatigue test. Methods Sixty first molars were selected and prepared for full-coverage crowns with three different designs(n = 20): Traditional –crowns with zirconia framework covered with feldspathic porcelain; Modified– crowns partially covered with veneering porcelain; and Monolithic–full-contour zirconia crowns. All specimens were treated with a glaze layer. Specimens were subjected to mechanical cycling (100N, 3Hz) with a piston with hemispherical tip (Ø=6 mm) until the specimens failed or up to 2×106 cycles. Every 500,000 cycles intervals, the fatigue tests were interrupted, and stereomicroscopy (10 X) was used to inspect the specimens for damage. We performed Weibull analysis of interval data to calculate the number of failures in each interval. Results The types and number of failures according to the groups were: cracking (Traditional-13, Modified-6) and chipping (Traditional-4) of the feldspathic porcelain, followed by delamination (Traditional-1) at the veneer/core interface and debonding (Monollithic-2) at the cementation interface. Weibull parameters (beta, scale; and eta, shape), with a two-sided confidence interval of 95%, were: Traditional – 1.25 and 0.9 × 106cycles; Modified– 0.58 and 11.7 × 106 cycles; and Monolithic – 1.05 and 16.5 × 106 cycles. Traditional crowns showed greater susceptibility to fatigue, the Modified group presented higher propensity to early failures, and the Monolithic group showed no susceptibility to fatigue. The Modified and Monolithic groups presented the highest number of crowns with no failures after the fatigue test. Conclusions The three crown designs presented significantly different behaviors under fatigue. The Modified and the Monolithic groups presented less probability to failure after 2×106cycles.