Fatigue-life and stress distribution of a glass-ceramic under different loading conditions

Lana, Tábata Mariana da Silva Dalla; Weber, Kátia Raquel; Medeiros, Juliana Arisi; Goedel, Fábio; Benetti, Paula; Borba, Márcia

doi:10.1590/0103-6440202305129

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Article • Braz. Dent. J. 34 (1) • Jan-Feb 2023 • https://doi.org/10.1590/0103-6440202305129 copy

Fatigue-life and stress distribution of a glass-ceramic under different loading conditions

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Abstract

This study aimed to evaluate the effect of different loading conditions on the mechanical behavior and stress distribution of a leucite-reinforced glass-ceramic. Plate-shaped ceramic specimens were obtained from leucite-reinforced glass-ceramic (1.5 × 8.4 × 8.3 mm) and adhesively cemented to a dentin analog substrate. Monotonic and cyclic contact fatigue tests were performed to simulate sphere-to-flat contact, using a 6 mm diameter spherical piston; and flat-to-flat contact, using a 3 mm diameter flat piston. For the monotonic test (n=20), a gradual compressive load (0.5 mm/min) was applied to the specimen using a universal testing machine. Failure load data were analyzed with Weibull statistics. The cyclic contact fatigue test was performed using protocols (load and a number of cycles) defined by the boundary technique (n=30). Fatigue data were analyzed using an inverse power law relationship and Weibull-lifetime distribution. The stress distribution was investigated using Finite Element Analysis (FEA). The monotonic and the fatigue Weibull modulus were similar among the two contact conditions. In fatigue, the slow crack growth exponent was greater for sphere-to-flat contact, which indicates that the load level had a greater effect on the specimen’s probability of failure. In conclusion, FEA showed different stress distribution for the tested loading conditions. The stress distribution and probability of fatigue failure of specimens tested in sphere-to-flat contact showed greater dependency to load level.

Key Words:
ceramics; biomechanics; stress; fatigue

Materials	E (GPa)	(
Glass-fiber reinforced epoxy resin - G10^*	14.9	0.31
Leucite-reinforced glass-ceramic²⁵25. Belli R, Wendler M, de Ligny D, Cicconi MR, Petschelt A, Peterlik H, et al. Chairside CAD/CAM materials. Part 1: Measurement of elastic constants and microstructural characterization. Dent Mater 2017;33:84-98.	65	0.25
Stainless steel ²²22. Maennig W. Statistical planning and evaluation of fatigue tests. A survey of recent results. Int J Fract 1975;11:123-9.	200	0.30

Group	L₀ (N)	95% CI - L₀ (N)	m	95% CI - m
FFC	1111^a	1034; 1196	6^a	4;8
SFC	1037^a	951; 1133	5^a	3;6

	Groups
	SFC		FFC
Load	P_f (%)	95% CI	P_f (%)	95% CI
30 N	4	0; 33	62	36; 87
40 N	11	2; 45	67	45; 89
50 N	23	8; 57	74	44; 95
60 N	41	22; 68	78	40; 99
80 N	79	68; 89	83	32; 99

Monotonic Compressive Load Test
Group		n	Radial	Cone	Combined
FFC		20	17 (85%)	3 (15%)	0 (0%)
SFC		20	12 (60%)	4 (20%)	4 (20%)
Cyclic Fatigue Test
Group	N. cycles	Load	n	Radial	Cone	Combined	Survived
FFC	100,000	69 N	10	10 (100%)	0 (0%)	0 (0%)	0 (0%)
	100,000 ? 200,000*	56 N	10	7 (70%)	0 (0%)	0 (0%)	3 (30%)
	200,000	49 N	10	7 (70%)	0 (0%)	0 (0%)	3 (30%)
SFC	100,000	98 N	10	8 (80%)	1 (10%)	1 (10%)	0 (0%)
	100,000 ? 200,000*	81 N	10	3 (30%)	1 (10%)	4 (40%)	2 (20%)
	200,000	69 N	10	6 (60%)	0 (0%)	0 (0%)	4 (40%)

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[1] Correspondence: Katia Raquel Weber. Address: Dental School, University of Passo Fundo, BR 285, Sao Jose, city Passo Fundo, state Rio Grande do Sul (RS), country Brazil. Telephone: (01155) 54-3316-8395/ 54-3311-3187. E-mail: katiaraquelweber@hotmail.com