Hierarchical Dependence of the Elastic-Modulus of Three Ceramic-Composite CAD/CAM Materials

Objectives: To measure the elastic modulus of three ceramic-composite CAD/CAM materials at the three different dimensions, the macro, micro, and nano.
Methods: Three novel ceramic-composite CAD/CAM materials (Vita Enamic, Lava Ultimate, and Cerasmart) have been selected. Rectangular cross-sections 10x5.67x1.03 mm³ (n=30) were prepared from standard sized milling blocks of each tested material. Optical images were obtained. Specimens were tested using three point bending (Instron), three point bend flexural response with a dynamic mechanical analyzer (DMA), nanoindentation systems, and finally, atomic force microscope (AFM). Data were analyzed with 1-way ANOVA (α=0.05).
Results: Vita Enamic showed the highest elastic modulus, followed by Lava Ultimate and Cerasmart respectively (p<0.001). Measurements at the micro and nano level resulted in bimodal distributions of the elastic modulus values associated with the various phases present with values higher and lower than those measured at the macro level.
Conclusions: The tested materials showed different elastic modulus at the different hierarchical levels that can be compared to enamel hierarchical structure.
Significance: Studying the mechanical properties of these novel materials at different hierarchical scales can help to understand their potential clinical performance, such as structural durability and opposing tooth wear and lead to more biomimetic like dental restorative materials.