IADR Abstract Archives
Fracture behavior of different CAD/CAM materials
Objectives: Initial LRF is a leucite-reinforced glass ceramic for processing using CAD/CAM technology. This study aimed to compare the fracture behavior of Initial LRF with two other feldspar-based ceramics.
Methods: 18 central incisor crowns were milled (Sirona MCXL CEREC In Lab-Machine) from different CAD/CAM materials (Initial LRF, IPS Empress CAD and Vita Mark II; n=6). Crowns were prepared according to the ceramic guidelines with an incisal anatomical reduction of 3 mm and a deep circular shoulder margin of 1 mm. The crowns were cemented on the metal post using GC G-CEM LinkForce dual-cure adhesive luting cement. The specimens were placed in a fracture resistance machine (Zwick Z-010) and a vertical load was applied under a 30° angle at a crosshead speed of 1 mm/min. Results were statistically analyzed with Weibull at a significance level of α=0.05; 95% pivotal confidence bounds were calculated as well using Monte Carlo simulation.
Results: The shape parameter ranged from 3.5 for Empress CAD to 12.2 for Initial LRF. While up to 10% of the samples of Vita Mark II and Empress CAD may fracture at values lower than 1000 N, probably more than 99% of Initial LRF samples will have a fracture strength of more than 1119N.
Conclusions: While the characteristic strengths were not that different, the reliability of the 3 ceramics was more variable. Initial LRF presented a more stable behaviour when compared to others, making this the most reliable ceramic tested here.
Methods: 18 central incisor crowns were milled (Sirona MCXL CEREC In Lab-Machine) from different CAD/CAM materials (Initial LRF, IPS Empress CAD and Vita Mark II; n=6). Crowns were prepared according to the ceramic guidelines with an incisal anatomical reduction of 3 mm and a deep circular shoulder margin of 1 mm. The crowns were cemented on the metal post using GC G-CEM LinkForce dual-cure adhesive luting cement. The specimens were placed in a fracture resistance machine (Zwick Z-010) and a vertical load was applied under a 30° angle at a crosshead speed of 1 mm/min. Results were statistically analyzed with Weibull at a significance level of α=0.05; 95% pivotal confidence bounds were calculated as well using Monte Carlo simulation.
Results: The shape parameter ranged from 3.5 for Empress CAD to 12.2 for Initial LRF. While up to 10% of the samples of Vita Mark II and Empress CAD may fracture at values lower than 1000 N, probably more than 99% of Initial LRF samples will have a fracture strength of more than 1119N.
Conclusions: While the characteristic strengths were not that different, the reliability of the 3 ceramics was more variable. Initial LRF presented a more stable behaviour when compared to others, making this the most reliable ceramic tested here.
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