Edmara T P Bergamo1, Satoshi Yamaguchi2, Paulo G Coelho3, Adolfo C O Lopes4, Chunwoo Lee2, Gerson Bonfante4, Ernesto B Benalcázar Jalkh4, Everardo N S de Araujo-Júnior4, Estevam A Bonfante4. 1. Department of Prosthodontics and Periodontology, University of São Paulo, Bauru School of Dentistry. 9-75, Otávio Pinheiro Brisola, 17012-901, Bauru, SP, Brazil. Electronic address: edmarabergamo@usp.br. 2. Department of Biomaterials Science, Osaka University Graduate School of Dentistry, 1-8 Yamadaoka, 565-0871, Suita, Osaka, Japan. 3. Department of Biomaterials and Biomimetics, Hansjorg Wyss Department of Plastic Surgery, Mechanical and Aerospace Engineering, New York University, 345 24th Street, 10010, New York City, NY, USA. 4. Department of Prosthodontics and Periodontology, University of São Paulo, Bauru School of Dentistry. 9-75, Otávio Pinheiro Brisola, 17012-901, Bauru, SP, Brazil.
Abstract
OBJECTIVE: To evaluate the fatigue survival, failure mode, and maximum principal stress (MP Stress) and strain (MP Strain) of resin-matrix ceramic systems used for implant-supported crowns. METHODS: Identical molar crowns were milled using four resin-matrix ceramics (n = 21/material): (i) Shofu Hard, (ii) Cerasmart (iii) Enamic, and (iv) Shofu HC. Crowns were cemented on the abutments, and the assembly underwent step-stress accelerated-life testing. Use level probability Weibull curves at 300 N were plotted and the reliability at 300, 500 and 800 N was calculated for a mission of 50,000 cycles. Fractographic analysis was performed using stereomicroscope and scanning electron microscope. MP Stress and MP Strain were determined by finite element analysis. RESULTS: While fatigue dictated failures for Cerasmart (β > 1), material strength controlled Shofu Hard, Enamic, and Shofu HC failures (β < 1). Shofu HC presented lower reliability at 300 N (79%) and 500 N (59%) than other systems (>90%), statistically different at 500 N. Enamic (57%) exhibited a significant reduction in the probability of survival at 800 N, significantly lower than Shofu Hard and Cerasmart; however, higher than Shofu HC (12%). Shofu Hard and Cerasmart (>93%) demonstrated no significant difference for any calculated mission (300-800 N). Failure mode predominantly involved resin-matrix ceramic fracture originated from occlusal cracks, corroborating with the MP Stress and Strain location, propagating through the proximal and cervical margins. SIGNIFICANCE: All resin-matrix ceramics crowns demonstrated high probability of survival in a physiological molar load, whereas Shofu Hard and Cerasmart outperformed Enamic and Shofu HC at higher loads. Material fracture comprised the main failure mode.
OBJECTIVE: To evaluate the fatigue survival, failure mode, and maximum principal stress (MP Stress) and strain (MP Strain) of resin-matrix ceramic systems used for implant-supported crowns. METHODS: Identical molar crowns were milled using four resin-matrix ceramics (n = 21/material): (i) Shofu Hard, (ii) Cerasmart (iii) Enamic, and (iv) Shofu HC. Crowns were cemented on the abutments, and the assembly underwent step-stress accelerated-life testing. Use level probability Weibull curves at 300 N were plotted and the reliability at 300, 500 and 800 N was calculated for a mission of 50,000 cycles. Fractographic analysis was performed using stereomicroscope and scanning electron microscope. MP Stress and MP Strain were determined by finite element analysis. RESULTS: While fatigue dictated failures for Cerasmart (β > 1), material strength controlled Shofu Hard, Enamic, and Shofu HC failures (β < 1). Shofu HC presented lower reliability at 300 N (79%) and 500 N (59%) than other systems (>90%), statistically different at 500 N. Enamic (57%) exhibited a significant reduction in the probability of survival at 800 N, significantly lower than Shofu Hard and Cerasmart; however, higher than Shofu HC (12%). Shofu Hard and Cerasmart (>93%) demonstrated no significant difference for any calculated mission (300-800 N). Failure mode predominantly involved resin-matrix ceramic fracture originated from occlusal cracks, corroborating with the MP Stress and Strain location, propagating through the proximal and cervical margins. SIGNIFICANCE: All resin-matrix ceramics crowns demonstrated high probability of survival in a physiological molar load, whereas Shofu Hard and Cerasmart outperformed Enamic and Shofu HC at higher loads. Material fracture comprised the main failure mode.