不同核心瓷与饰面瓷厚度比对氧化锆双层瓷结构强度的影响*

背景：氧化锆陶瓷的强度和韧性均优于传统的长石瓷和氧化铝陶瓷,其双层瓷结构的弯曲强度与核心瓷/饰面瓷厚度比相关。 目的：分析不同核心瓷与饰面瓷厚度比对氧化锆双层瓷结构强度及断裂方式的影响。 方法：将完全烧结的氧化锆块切割成0.5,0.8,1.0,1.2,1.5,2.0 mm 6种不同厚度的氧化锆瓷片,除2.0 mm厚度组(对照组)外,用自制磨具在0.5,0.8,1.0,1.2,1.5 mm厚度的氧化锆瓷片上堆塑饰面瓷,使得核心瓷与饰面瓷的厚度比分别为1∶3,2∶3,1∶1,3∶2,3∶1。 结果与结论：随着核心瓷与饰面瓷厚度比的增加,氧化锆双层瓷结构强度也随之增强。除核心瓷与饰面瓷厚度比2∶3组与1∶1组、3∶2组与3∶1组间差异无显著性意义外(P > 0.05),其余组间差异均有显著性意义(P < 0.05)。核心瓷与饰面瓷厚度比为1∶3、2∶3组均出现分层,断裂碎片在3片以上,而其他4组样本未出现分层,断裂碎片多为2片。表明核心瓷/饰面瓷厚度比可显著影响氧化锆双层瓷的结构强度。

Different thickness ratios of core to veneer influence the flexural strength of bilayered zirconia ceramic

BACKGROUND: Zirconia ceramic has superior strength and toughness to traditional feldspar porcelain and alumina ceramic; however, the flexural strength relates to the thickness ratio of core to veneer. OBJECTIVE: To evaluate the effect of different core: veneer thickness ratios to veneer on the flexural strength and failure mode of bilayered dental ceramic sheet specimens. METHODS: Zirconia ceramic blocks (15 mm×5.0 mm) after sintering were cut into 30 sheets with low speed saw according to the following thickness: 0.5 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.5 mm and 2.0 mm. After veneering porcelain was fired, all bilayered ceramic sheets and simple zirconia sheets had same specimen thickness of 2.0 mm and equally divided into six groups of five each according to core: veneer thickness ratio: A group (1:3), B group (2:3), C group (1:1), D group (3:2), E group (3:1) and F group of simple zirconia as control. All specimens were mounted in a custom-made jig (span: 12 mm) and subjected to a 3-point flexural testing in a universal testing machine. Recorded maximum load (N) of each specimen and calculated flexural strength (MPa). RESULTS AND CONCLUSION: Mean flexural strength (MPa) of 6 groups were as follows: A group (522.17±41.11), B group (664.00±68.44), C group (695.06±31.16), D group (794.10±46.11), E group (843.20±38.22) and F group (926.89±44.46). The strength of bilayered ceramic specimens was smaller than simple zirconia ceramic. There was statistically significant difference between any two of six groups except B and C, D and E. The number of fracture fragments in A and B groups was higher than that in the other groups, and most of specimens presented with delaminations in A and B groups and no in the others. Different core: veneer thickness ratios could significantly influence the flexural strength and failure mode of bilayered zirconia and veneering porcelain materials, and flexural strength could be enhanced with the increase of core:veneer thickness ratio.