KU Leuven (University of Leuven), Department of Oral Health Sciences, BIOMAT & University Hospitals Leuven, Dentistry, Kapucijnenvoer 7, blok a bus 7001, B-3000 Leuven, Belgium; Tokyo Medical and Dental University, Graduate School of Medical and Dental Sciences, Gerodontology and Oral Rehabilitation, 1-5-45 Yushima, Bunkyo, Tokyo 113-8510, Japan.
KU Leuven (University of Leuven), Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Heverlee, Belgium.
Dent Mater. 2017 Apr;33(4):e147-e154. doi: 10.1016/j.dental.2016.12.007. Epub 2017 Jan 8.
To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades.
Fully-sintered zirconia specimens (4.0×3.0×45.0mm) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/AlO zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND+HEAT': (1) followed by annealing at 1100°C for 30min; (3) 'GROUND+AlO SANDBLASTED': (1) followed by sandblasting using AlO; (4) 'GROUND+CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine.
Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength.
Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia.
评估表面处理和热退火对两种研磨牙科氧化锆的四点弯曲强度的影响。
将全烧结氧化锆（LAVA Plus，3M ESPE）和氧化锆/氧化铝（ZirTough，Kuraray Noritake）的 Y-TZP 氧化锆试件（4.0×3.0×45.0mm）进行四种表面处理：（1）“研磨”：所有表面均在研磨机上用金刚石涂层砂轮研磨；（2）“研磨+退火”：（1）随后在 1100°C 下退火 30min；（3）“研磨+AlO 喷砂”：（1）随后用 AlO 喷砂；（4）“研磨+CoJet 喷砂”：（1）随后用 tribochemical silica（CoJet）喷砂。微拉曼光谱用于评估氧化锆相组成和潜在诱导的残余应力。四点弯曲强度使用万能材料试验机进行测量。
威布尔分析显示，ZirTough（Kuraray Noritake）的威布尔模数明显较高，特征强度略高。对于两种氧化锆等级，“研磨”氧化锆的威布尔模数最低，特征强度最高。喷砂几乎不会改变弯曲强度，但会大大提高研磨氧化锆的威布尔模数，而热处理会提高两种氧化锆等级的威布尔模数，但会导致弯曲强度显著降低。微拉曼分析显示出更高的残余压应力，这与弯曲强度的增加相关。
残余压应力增加了牙科氧化锆的弯曲强度。热退火大大降低了弯曲强度，但提高了研磨氧化锆的一致性（可靠性）。
