Masanao Inokoshi1, Fei Zhang2, Kim Vanmeensel2, Jan De Munck3, Shunsuke Minakuchi4, Ignace Naert3, Jozef Vleugels2, Bart Van Meerbeek5. 1. 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. 2. KU Leuven (University of Leuven), Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Heverlee, Belgium. 3. 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. 4. 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. 5. 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. Electronic address: bart.vanmeerbeek@kuleuven.be.
Abstract
OBJECTIVE: To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades. METHODS: Fully-sintered zirconia specimens (4.0×3.0×45.0mm3) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al2O3 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+Al2O3 SANDBLASTED': (1) followed by sandblasting using Al2O3; (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. RESULTS: 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. SIGNIFICANCE: 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.
OBJECTIVE: To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades. METHODS: Fully-sintered zirconia specimens (4.0×3.0×45.0mm3) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al2O3 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+Al2O3 SANDBLASTED': (1) followed by sandblasting using Al2O3; (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. RESULTS: 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. SIGNIFICANCE: 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.
Authors: Jie Lin; Jukka Pekka Matinlinna; Akikazu Shinya; Michael George Botelho; Zhiqiang Zheng Journal: Odontology Date: 2017-12-14 Impact factor: 2.634
Authors: Stephanie Assimakopoulos Garófalo; Martin Wehner; Andreas Dohrn; Marin Dean Bilandžić; Christian Roos; Richard Johannes Wierichs; Hendrik Meyer-Lueckel; Ana Cecilia Corrêa Aranha; Marcella Esteves-Oliveira Journal: Clin Oral Investig Date: 2021-08-17 Impact factor: 3.606