Department of Dental Materials and Prosthodontics, São José dos Campos Dental School, UNESP - Universidade Estadual Paulista, São José dos Campos, São Paulo, Brazil.
Dent Mater. 2013 Oct;29(10):1063-72. doi: 10.1016/j.dental.2013.07.019. Epub 2013 Aug 17.
To determine whether the thickness, processing technique, and cooling protocol of veneer ceramic influence the flexural strength of a bilayer ceramic system.
Sixty-four bar-shaped specimens (20mm×4mm×1mm) of yttria-stabilized tetragonal zirconia (Vita In-Ceram YZ, Vita) were fabricated (ISO 6872) and randomly divided into 8 groups (n=8) according to the factors "processing technique" (P - PM9 and V - VM9), "thickness" (1mm and 3mm), and "cooling protocol" (S - slow and F - fast). The veneer ceramics were applied only over one side of the bar-shaped specimens. All specimens were mechanically cycled (2×10(6) cycles, 84N, 3.4Hz, in water), with the veneer ceramic under tension. Then, the specimens were tested in 4-point bending (1mm/min, load 100kgf, in water), also with the veneer ceramic under tension, and the maximum load was recorded at first sign of fracture. The flexural strength (σ) was calculated, and the mode of failure was determined by stereomicroscopy (30×). The data (MPa) were analyzed statistically by 3-way ANOVA and Tukey's test (α=0.05).
ANOVA revealed that the factor "thickness" (p=0.0001) was statistically significant, unlike the factors "processing technique" (p=0.6025) and "cooling protocol" (p=0.4199). The predominant mode of failure was cracking.
The thickness of the veneer ceramic has an influence on the mechanical strength of the bilayer ceramic system, regardless of processing technique and cooling protocol of the veneer ceramic.
确定贴面陶瓷的厚度、加工技术和冷却方案是否会影响双层陶瓷系统的弯曲强度。
采用氧化钇稳定四方氧化锆（Vita In-Ceram YZ，Vita）制作 64 个条形试件（20mm×4mm×1mm）（ISO 6872），并根据“加工技术”（P-PM9 和 V-VM9）、“厚度”（1mm 和 3mm）和“冷却方案”（S-慢和 F-快）将其随机分为 8 组（每组 8 个试件）。仅在条形试件的一侧应用贴面陶瓷。所有试件均进行机械循环（2×10(6)次循环，84N，3.4Hz，水中），使贴面陶瓷处于拉伸状态。然后，在四点弯曲试验机中（1mm/min，载荷 100kgf，水中）对试件进行测试，也使贴面陶瓷处于拉伸状态，并在首次出现断裂时记录最大载荷。计算弯曲强度（σ），并通过立体显微镜（30×）确定失效模式。通过三因素方差分析和 Tukey 检验（α=0.05）对数据（MPa）进行统计学分析。
方差分析显示，“厚度”因素（p=0.0001）具有统计学意义，而“加工技术”（p=0.6025）和“冷却方案”（p=0.4199）因素则没有统计学意义。主要失效模式为开裂。
贴面陶瓷的厚度会影响双层陶瓷系统的机械强度，而与贴面陶瓷的加工技术和冷却方案无关。
