Accelerated loading frequency does not influence the fatigue behavior of polymer infiltrated ceramic network or lithium disilicate glass-ceramic restorations

• Published in: Journal of the mechanical behavior of biomedical materials 2020-10, Vol.110, p.103905-103905, Article 103905
• Main Authors: Velho, Helder Callegaro, Dapieve, Kiara Serafini, Rocha Pereira, Gabriel Kalil, Fraga, Sara, Valandro, Luiz Felipe, Venturini, Andressa Borin
• Format: Article
• Language: English
• Subjects: Ceramics; Computer-Aided Design; Dental Porcelain; Dental Restoration Failure; Dental Stress Analysis; Fatigue phenomena; Fatigue testing parameters; Glass-ceramics; Hybrid ceramics; Materials Testing; Mechanical cycling; Polymers; Surface Properties
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2020.103905

This study aimed to evaluate the influence of loading frequency on the fatigue mechanical behavior of adhesively cemented polymer-infiltrated ceramic-network (PICN) and lithium disilicate (LD) simplified monolithic restorations. Thirty (30) disc-shaped specimens (Ø = 10 mm; thickness = 1.0 mm) of each ceramic material (PICN – Enamic, Vita Zahnfabrik or LD – IPS e.max CAD, Ivoclar Vivadent) were produced and adhesively cemented onto dentin analogue discs made of fiber and epoxy resin material (Ø = 10 mm; thickness = 2.0 mm). PICN and LD cemented assemblies were randomly allocated into 2 groups (n = 15) according to the loading frequency used for the fatigue testing (20 Hz or 2 Hz), composing the PICN_20, PICN_2, LD_20 and LD_2 testing groups. Fatigue tests were run using the step-stress approach (initial load = 200 N; step-size = 100 N; 10,000 cycles per step) and the collected data (fatigue failure load – FFL and number of cycles for failure – CFF) were analyzed by survival tests (Kaplan Meier and Mantel-Cox) and Weibull analysis. Fractographic analysis of failed specimens were also performed. No statistically significant differences were detected in relation to FFL and CFF between the groups within the same ceramic material (PICN_20: 1127 N/102,667 cycles = PICN_2: 1120 N/102,000 cycles; LD_20: 980 N/88,000 cycles = LD_2: 900 N/80,000 cycles). All failures were radial cracks in the cementation surface. Therefore, the use of a 20 Hz loading frequency shows to be a viable alternative to accelerate cyclic fatigue tests without affecting the fatigue mechanical behavior and the failure pattern of simplified restorations made of lithium disilicate glass ceramic or polymer infiltrated ceramic network bonded to the dentin analogue. •The influence of cyclic loading frequency on fatigue properties was evaluated.•Loading frequency does not affect the fatigue behavior of lithium disilicate ceramic.•Loading frequency does not affect the fatigue behavior of polymer infiltrated ceramic.•Loading frequency does not influence the failure pattern.•The use of 20 Hz frequency is validated to accelerate fatigue tests on such materials.