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首页> 外文期刊>The Journal of Prosthetic Dentistry >Crack propensity of porcelain laminate veneers: A simulated operatory evaluation.
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Crack propensity of porcelain laminate veneers: A simulated operatory evaluation.

机译：陶瓷层压板的裂纹倾向：模拟操作评估。

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STATEMENT OF PROBLEM: Anterior teeth are especially subject to the thermal variations of ingested food and drinks. Postoperative cracks of porcelain laminates are considered a possible consequence of polymerization shrinkage, function, and thermocycling. PURPOSE: This investigation was conducted to define the parameters associated with the development of cracks in porcelain veneers using cyclic thermal fatigue. MATERIAL AND METHODS: Twenty-seven maxillary incisors were restored with porcelain laminate veneers and subjected to thermocycling (5 degrees C to 50 degrees C) for 1000 cycles. Ceramic cracks were reported for 11 of the 27 specimens. Teeth were sectioned and prepared for SEM analysis. Measurements of the ceramic and the luting composite thicknesses were performed for each specimen at different restoration locations (facial, incisal, and proximal). RESULTS: No significant differences in the ceramic or the luting composite thicknesses were observed between cracked and uncracked specimens. However, significant differences were observed in the ratio of the ceramic and luting composite thicknesses. Most cracked samples exhibited a ratio at the facial location below 3.0 (2.6 +/- 0.35), whereas most noncracked specimens were above this value (3.9 +/- 0.19). Incisal and especially proximal measurements alone were not significantly different between cracked versus uncracked specimens. Ceramic was slightly thinner in the facial aspect than in the proximal aspect, which was also thinner than the incisal aspect. Composite in the facial aspect was thinner in the cervical area than in the incisal third of the tooth. CONCLUSIONS: Significant cyclic temperature changes can induce the development of flaws in porcelain veneers. Control of tooth reduction and the application of die spacers during laboratory procedures undoubtedly represent key elements; a sufficient and even thickness of ceramic combined with a minimal thickness of luting composite will provide the restoration with a favorable configuration with regard to crack propensity, namely, a ceramic and luting composite thickness ratio above 3.
机译：问题陈述：前牙特别容易受到摄入食物和饮料的热变化的影响。陶瓷层压板的术后裂纹被认为是聚合收缩，功能和热循环的可能结果。目的：进行这项研究是为了确定与使用循环热疲劳的瓷贴面中裂纹发展相关的参数。材料与方法：用瓷贴面修复了二十七个上颌切牙，并进行了热循环（5℃至50℃）1000个循环。 27个样品中有11个报告了陶瓷裂纹。牙齿被切成薄片并准备用于SEM分析。在不同的修复位置（面部，切牙和近端）对每个样品进行了陶瓷厚度和浸润复合材料厚度的测量。结果：在裂纹和未裂纹的样品之间，陶瓷或熔结复合材料的厚度均未发现明显差异。然而，观察到陶瓷和浸润复合材料厚度的比率存在显着差异。大多数破裂样品在面部位置的比率低于3.0（2.6 +/- 0.35），而大多数未破裂样品的比率高于该值（3.9 +/- 0.19）。单独的切牙和特别是近端测量在破裂和未破裂样品之间没有显着差异。陶瓷在面部方面比在近端方面稍薄，也比切牙方面薄。面部方面的复合材料在宫颈区域比在牙齿的切牙三分之一处更薄。结论：明显的循环温度变化可引起瓷贴面缺陷的发展。在实验室过程中控制牙齿的减少和模具垫片的应用无疑是关键要素。足够均匀的陶瓷厚度和最小厚度的熔结复合材料将为修复体提供良好的裂纹倾向性，即陶瓷与熔结复合材料的厚度比大于3。

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