Anusavice K J, Zhang N Z
Department of Dental Biomaterials, College of Dentistry, University of Florida, Gainesville 32610-0446, USA.
J Dent Res. 1998 Jul;77(7):1553-9. doi: 10.1177/00220345980770071101.
Fluorocanasite (Al2O3-CaO-F-K2O-Na2O-SiO2) glass-ceramics exhibit fracture toughness values of up to 5.0 MPa x m1/2. However, their chemical durability is not adequate for dental applications. The objective of this study was to test the hypothesis that an increased concentration of Al2O3 can increase the chemical durability of fluorocanasite-based glass-ceramics. Glass frits containing 2 wt% (CAN2), 5 wt% (CAN5), and 10 wt% Al2O3 (CAN10) were melted individually, poured into a graphite mold, and cut into 16-mm-diam. x 2-mm-thick disks. Each disk was crystallized at 850 degrees C for 6 hrs. The disks were immersed in a solution of de-ionized-distilled water, 4% acetic acid, or a pH 1 buffer solution, and sealed in 90-mL Teflon containers. Corrosion testing was performed by means of vibrational motion at 60 cycles per min in a shaker-bath at 80 degrees C for 15 days. Solution analyses were performed by means of a pH meter, an atomic absorption spectrophotometer, and an inductively coupled plasma spectrometer. Samples exposed to 4% acetic acid solution exhibited a mean weight loss rate (WLR) for the control group (Dicor) of 0.04+/-0.01 mg/cm2 day, which was significantly lower (p < or = 0.0001) than the mean WLR of the CAN2 (1.08+/-0.02 mg/cm2 x day), CAN5 (1.31+/-0.02 mg/cm2 x day), and CAN10(1.51+/-0.05 mg/cm2 x day) groups. The reduced durability of fluorocanasite-based glass-ceramics with increasing Al2O3 concentration is most likely associated with a more uniform distribution of smaller crystals during heat treatment of the glass.
氟碱钙霞石（Al2O3-CaO-F-K2O-Na2O-SiO2）微晶玻璃的断裂韧性值高达5.0 MPa×m1/2。然而，它们的化学耐久性不足以用于牙科应用。本研究的目的是检验以下假设：增加Al2O3的浓度可以提高氟碱钙霞石基微晶玻璃的化学耐久性。分别熔化含有2 wt%（CAN2）、5 wt%（CAN5）和10 wt% Al2O3（CAN10）的玻璃料，倒入石墨模具中，并切割成直径16毫米、厚2毫米的圆盘。每个圆盘在850℃下结晶6小时。将圆盘浸入去离子蒸馏水、4%乙酸或pH 1缓冲溶液中，并密封在90毫升的聚四氟乙烯容器中。通过在80℃的摇床浴中以每分钟60次循环的振动运动进行15天的腐蚀测试。通过pH计、原子吸收分光光度计和电感耦合等离子体光谱仪进行溶液分析。暴露于4%乙酸溶液中的样品，对照组（Dicor）的平均失重率（WLR）为0.04±0.01 mg/cm2·天，显著低于CAN2组（1.08±0.02 mg/cm2·天）、CAN5组（1.31±0.02 mg/cm2·天）和CAN组10（1.51±0.05 mg/cm2·天）的平均WLR（p≤0.0001）。随着Al2O3浓度增加，氟碱钙霞石基微晶玻璃耐久性降低，这很可能与玻璃热处理过程中较小晶体更均匀的分布有关。
