Category: Laboratory Research
Repeated Firings Effect on Biaxial-Flexural-Strength of Lithium-Disilicate in Different Thicknesses
Sarah Alsaleha | Sillas Duartea | Jin-Ho Pharka* (phark@usc.edu)
aDepartment of Operative Dentistry, Herman Ostrow School of Dentistry University of Southern California, Los Angeles, CA, USA
Objective: To evaluate the biaxial flexural strength (BFS) of four CAD/CAM lithium disilicate reinforced glass ceramic; IPS e.max CAD (EX) and Amber Mill (AM) as “lab-side,” and Initial LiSi Block (LS) and n! ce (NC) as “chair-side” according to the effect of two thicknesses and repeated firings.
Methods: Four hundred eighty (n=480) discs were prepared in total with a diameter of 12.00 mm (±0.02). Each selected material (n=120) was divided into two thicknesses: 1.00 mm (±0.03) and 0.5 mm (±0.02). The specimens were subdivided according to firings: baseline (BL), one firing (1F), three firings (3F), and five firings (5F). The firings cycles were performed according to the manufacturers’ instructions. The BFS test was performed according to ISO 6872-2015. BFS data were analyzed using ANOVA and Weibull analysis.
Results: The BFS of the materials differed from each other (EX=AM>NC>LS). A significant difference was found between the firings, regardless of the thickness, and the general ranking of firings was (3F>5F>1F>BL). Higher thickness (1.00 mm) presented a higher BFS value. Higher Weibull modulus and characteristic strength values were observed with lab-side vs. chair-side materials.
Conclusion: Repeated firings significantly affected the BFS of EX, AM, LS, and NC CAD/CAM lithium disilicate materials. The BFS increased with increased thickness. Lab-side materials (EX and AM) have a lower probability of failure than chair-side materials (LS and NC).
Funding/Conflict of Interest: none
Keywords: biaxial flexural strength, firing, lithium dislicate reinforced glass ceramic, thickness
