Fatigue failure load of zirconia-reinforced lithium silicate glass ceramic cemented to a dentin analogue: Effect of etching time and hydrofluoric acid concentration

Abstract

This study aimed to evaluate the effect of etching time and hydrofluoric acid (HF) concentration on the fatigue failure load and surface characteristics of zirconia-reinforced lithium silicate glass (ZLS) ceramic cemented to a dentin-like, fiber reinforced epoxy resin. Ceramic (Suprinity, VITA) (1.0mm thick) and epoxy resin (2.5mm thick) discs (10mm diameter) were produced. The bonding surface of the ceramic samples was nonetched (control group), or etched for 30, 60 or 90s by 5% or 10% HF. The epoxy resin discs were etched by 10% HF for 30s followed by the application of an adhesive material (Single Bond Universal, 3M ESPE). Pairs of ceramic/epoxy resin discs were cemented with a dual cure resin cement. The fatigue failure load was determined by the staircase method (500,000 cycles at 20Hz; initial load = 925N; step size = 45N). In 10% HF the etching time was shown to influence the fatigue failure load, which increased as the etching time increased (30s < 60s < 90s), and in 5% HF the fatigue failure load was not shown to be affected by the etching time; the lowest fatigue failure loads were produced in the control group without ceramic etching followed by 10% HF acid etching for 30s. Topography analysis showed variations based on the etching protocols. All fractures (radial cracks) were shown to originate from defects at the ceramic surface on the cementing interface. For fatigue loading improvements of ZLS ceramic, 10% HF acid etching for 90s and silanization of the ceramic surface is recommended.

Effect of total occlusal convergence on fit and fracture resistance of zirconia-reinforced lithium silicate crowns

“…In both the study at hand and that of Sieper et al,26 the ceramic crowns were etched and bonded to the underlying structure. The strengthening effect of the adhesive cementation might have contributed to the favorable outcomes 46. Preis et al45 compared the fracture resistance of conventionally cemented, self adhesively cemented, and adhesively bonded ZLS crowns subjected to combined thermal cycling and mechanical loading.…”

“…Fracture resistance and resistance to fatigue failure under intraoral forces are important prerequisites for a successful restoration 46–50. Tooth preparation TOC also influences the amount of ceramic material used to achieve acceptable contours.…”

Fatigue failure load of two resin-bonded zirconia-reinforced lithium silicate glass-ceramics: Effect of ceramic thickness

“…Then, twenty specimens (n = 20) of each condition were subjected to an cyclic fatigue test under water in an electrodynamic machine (Instron ElectroPuls E3000, Instron Corporation, Norwood, MA, United States). A stainless-steel sphere ( = 40 mm) [20,22,25,26] was used to apply the load at the center of the specimen (i.e., center of the occlusal surface), which was positioned inside an attached cylindrical metal ring stabilized in a flat steel base. An adhesive tape (110 m) was fixed on the occlusal side of the specimens to improve contact with the sphere [27], and an additional thin sheet of a non-rigid material (cellophane, 2.5 m) was placed between the piston and the specimen to better distribute the contact surface pressure according to previous studies using the same methodology [22,28].…”

“…After testing, the mean fatigue failure load (L f ), standard deviation (SD) and 95% confidence interval were calculated using the Dixon and Mood method [30], which involves maximum-likelihood estimation, assuming that data follows a normal distribution [29]. This methodology was previously well described in the literature [16,18,22,31].…”

“…Pairs of discs (ceramic and epoxy resin) were randomly assigned into four groups (n = 25) from each ZLS ceramic in accordance to the thickness factor ( Table 2). The test assembly reproduced an occlusal restoration [11,22], which had a final diameter of 10 mm (average dimension of molars) [23] and a final thickness of 3.5 mm (ceramic thickness + epoxy resin thickness = 3.5 mm), which was chosen as being equivalent to the average thickness from the roof of the pulp chamber to the occlusal surface [24]. The cementation surfaces of the ceramic and of the resin epoxy were etched with 5% hydrofluoric acid (Acido Gel 5%, Maquira Ind.…”