Cyclic Loading Effect on Flexural Strength of Chairside CAD/CAM Materials

Objectives: To investigate the effect of cyclic loading on the flexural strength of chairside CAD/CAM restorative materials.
Methods: Five CAD/CAM materials were included in this study: A. Telio CAD (Ivoclar), B. VITA CAD-Temp (VITA Zahnfabrik), C. Lava Ultimate Restorative (3M ESPE), D. e.max CAD (Ivoclar), E. Paradigm MZ100 Block (3M ESPE). A total 40 rectangular specimens per material were prepared with the dimension of 14mm×4mm×2mm. Ten specimens from each material were subjected to three-point bending test on a 10mm span, using Instron universal mechanical tester (5566A) at a crosshead speed of 0.5mm/min. Additional specimens were subjected to 20k, 40k and 60k loading cycles (10 from each group/ condition) at 1 Hz in water baths under a pneumatically driven fatigue tester using a maximum load matching 30% of the mean fracture load. The cyclic loaded specimens were then subjected to the same three-point bending test. Flexural strength data were analyzed by ANOVA and Tukey HSD post hoc test (a=0.05) by JMP11.
Results: Mean flexural strength values (MPa) and standard deviations are shown in the bar graph below:
Conclusions: There was significant influence of cyclic loading on flexural strength of e.max CAD (P<0.001), MZ100 (P<0.002) and Vita CAD-Temp (P<0.001). Within the testing conditions of this study, cyclic loading didn’t significantly decrease the flexural strength of Telio CAD, and Lava Ultimate Restorative (p>0.05).