Flexural Strength of Resin Nano-ceramic Material Versus other CAD/CAM Materials

Introduction: There are several materials available to fabricate restorations with the use of chair-side CAD/CAM technology, such as feldspathic ceramics, glass ceramics and composite resins. Ease of milling and flexural strength are important properties of a CAD/CAM material.

Objective: The objective of this study was to compare the flexural strength of 8 CAD/CAM materials. 

Method: Ten bars, 15 mm x 3.5 mm x 1.5 mm, were made of 2 provisional restorative materials, CAD-temp (Vita) (group 1) and Telio CAD (Ivoclar) (group 2); 2 feldspathic ceramic materials, Mark II (Vita) (group 3) and ProCAD (Ivoclar) (group 4); 2 glass ceramic materials, e.max CAD (Ivoclar) (group 5) and Empress CAD (Ivoclar) (group 6); 1 resin-based composite material, MZ100 (3M ESPE) (group 7); and an experimental resin nano-ceramic material (3M ESPE) (group 8). Bars were cut from CAD/CAM blocks with a saw (Isomet; Buehler), and were tested with a 3-point bending test in a universal testing machine (5566A, Instron) with a 1-kN cell, a 0.5mm/min cross-head speed and a 10-mm span. Results were analyzed with ANOVA followed by Tukey HSD test (α=0.05).

Result: Means and standard deviations of flexural strength values (MPa) were: (group 1) 102.09±5.07; (group 2) 181.49±7.99; (group 3) 95.58±9.09; (group 4) 373.82±63.09; (group 5) 88.01±35.28; (group 6) 103.26±16.19; (group 7) 183.09±22.69 and (group 8) 233.91±12.19. The e.max CAD material recorded a significantly higher mean flexural than all other materials. The resin nano-ceramic material recorded the second highest strength. There was no statistically significant difference between the MZ100 and Telio CAD materials, and no statistically significant differences among ProCAD, CAD-temp, Mark II and Empress CAD materials.

Conclusion: Within the limitations of this study, it was concluded that the experimental material demonstrated the second highest mean value for flexural strength. MZ100 and Telio Cad recorded higher flexural strengths than some ceramic materials.