Int J Prosthodont. 2022 Jul-Aug;35(4):469-479. doi: 10.11607/ijp.7551.
To evaluate the biaxial flexural strength of different porcelain-to-zirconia thickness ratios and bonding strategies of a stress-free bilayer CAD/CAM ceramic system.
A total of 60 zirconia discs (diameter: 15 mm; thickness: 0.3 or 0.5 mm; n = 30 for each thickness) were divided into six groups (n = 10 each) according to porcelain-to-zirconia ratio and bonding strategy: VM/Zr (control): zirconia discs veneered with a feldspathic ceramic (VM 9, Vita) in 0.9-mm and 0.7-mm thicknesses using a conventional hand-layering technique; VB/Zr-SBU: zirconia discs airborne particle-abraded with 50-μm AlO particles followed by an MDP primer application (Single Bond Universal, 3M) and bonded to the porcelain with a resin cement (Panavia F 2.0, Kuraray); and VB/Zr-RC: zirconia discs airborne particle-abraded with 30-μm silica-coated AlO particles and silanized and bonded to the porcelain with the same resin cement. Before cementation, the VB (Vitablocs II) discs were etched with 5% hydrofluoric acid (60 seconds), followed by silane application. The bilayers (thickness = 1.2 mm) were loaded with 750 g while light curing the resin cement. Two porcelain-to-zirconia thickness ratios were evaluated: 0.9: 0.3 mm and 0.7: 0.5 mm. All groups were subjected to 106 mechanical cycles, followed by a biaxial flexural test. Data (MPa) were subjected to two-way analysis of variance (ANOVA), Tukey test (5%), and Weibull analyses.
Two-way ANOVA revealed that the factor porcelain-to-zirconia ratio (P = .0556) was not significant; however, the bonding strategy factor was statistically significant. Among the 0.5-mm zirconia groups, the VB/Zr-SBU group presented higher flexural strength (s) than the VM/Zr or VB/Zr-RC groups. Similar results were also found for the 0.3-mm zirconia groups, in which the VB/Zr-SBU group also presented higher strength than the others, which were similar in comparison (Tukey). The Weibull modulus was similar among the groups; however, the characteristic strength was significantly different (P = .000).
The zirconia bonding strategy with 50-μm AlO airborne-particle abrasion, followed by a primer application, increases the flexural strength of a stress-free bilayer CAD/CAM ceramic system.
评估一种无应力双层 CAD/CAM 陶瓷系统中不同瓷-氧化锆厚度比和结合策略的双轴弯曲强度。
共 60 个氧化锆圆盘（直径：15mm；厚度：0.3 或 0.5mm；每种厚度各 30 个，共 30 个）根据瓷-氧化锆比和结合策略分为六组（每组 10 个）：VM/Zr（对照）：使用传统的手工分层技术，在 0.9mm 和 0.7mm 厚度下用长石陶瓷（VM9，Vita）覆盖氧化锆圆盘；VB/Zr-SBU：氧化锆圆盘经 50-μmAlO 颗粒空气动力喷砂处理，然后应用 MDP 底漆（Single Bond Universal，3M）并用树脂水泥（Panavia F2.0，Kuraray）将其与瓷结合；和 VB/Zr-RC：氧化锆圆盘经 30-μm 硅涂层 AlO 颗粒空气动力喷砂处理并硅烷化，并用相同的树脂水泥与瓷结合。在粘固前，用 5%氢氟酸（60 秒）蚀刻 VB（Vitablocs II）圆盘，然后进行硅烷处理。将双层（厚度=1.2mm）在 750g 下加载并进行树脂水泥光固化。评估了两种瓷-氧化锆厚度比：0.9:0.3mm 和 0.7:0.5mm。所有组均进行 106 次机械循环，然后进行双轴弯曲试验。数据（MPa）进行双向方差分析（ANOVA），Tukey 检验（5%）和威布尔分析。
双向方差分析显示，瓷-氧化锆比（P=0.0556）因素不显著；然而，结合策略因素具有统计学意义。在 0.5mm 氧化锆组中，VB/Zr-SBU 组的弯曲强度（s）高于 VM/Zr 或 VB/Zr-RC 组。在 0.3mm 氧化锆组中也发现了类似的结果，其中 VB/Zr-SBU 组的强度也高于其他组，而其他组的强度相似（Tukey）。各组的威布尔模数相似，但特征强度差异显著（P=0.000）。
采用 50-μmAlO 空气动力喷砂，然后应用底漆的氧化锆结合策略可提高无应力双层 CAD/CAM 陶瓷系统的弯曲强度。
