Fatigue Behaviour of Fully Crystallised Glass-Based CAD/CAM Ceramics

Abstract

<p><strong>Objectives</strong>: This study aimed to investigate the fatigue behaviour of a novel fully crystallised lithium disilicate CAD/CAM ceramic in comparison to glass-based CAD/CAM materials.<br><strong>Methods</strong>: The novel fully crystallised lithium disilicate CAD/CAM block (Initial LiSi Block, GC Corp; LISI), along with a fully sintered zirconia-reinforced lithium silicate (ZLS) glass-ceramic (Celtra DUO, Dentsply Sirona; DUO) and a leucite-based glass-ceramic (Empress CAD, Ivoclar-Vivadent; EMP), all in LT A2 shade, were included in the study. Anatomic maxillary premolar crowns were CAD/CAM designed and milled (CEREC MC XL, Dentsply Sirona). After adhesively luting the crowns to dentine analogue abutments (30% glass fibre reinforced polyamide-nylon 6,6; RPN), specimens were subjected to wet cyclic loading in a step-stress manner (500 N initial load, 100 N step size, 100, 000 cycles per step, 20 Hz frequency; n = 12). Data were statistically analysed using one-way ANOVA, Kruskal-Wallis one-way ANOVA, and median-rank Weibull analysis, while the survival probability estimation was performed by Mantel-Cox Log-Rank test with 95% confidence intervals. The significance level was set to 0.05.<br><strong>Results</strong>: The fatigue failure load (FFL) ranked LISI (1067 ± 172 N), DUO (983 ± 164 N), and EMP (900 ± 217 N). No significant difference was found in the FFL and number of cycles until failure (NCF) among the three groups (p = 0.106 and 0.061, respectively), while LISI presented significantly higher NCF than EMP (p = 0.049). Although the three materials presented comparable survival probabilities (p = 0.165), LISI showed the highest FFL, the highest m, and the lowest relative standard deviation (RSD) of the FFL.<br><strong>Conclusions</strong>: Three glass-based CAD/CAM ceramics presented satisfactory fatigue properties for single-unit restorations, with the fully crystallised lithium disilicate ceramic showing higher reliabilities under fatigue loading.<br></p>