Finite element analysis and nanomechanical properties of composite and ceramic dental onlays.

The aim is to evaluate the mechanical properties of the composite and ceramic based indirect restorative materials used in dental treatments with scanning nanoindentation test (NT). Finite element analysis (FEA) was applied to investigate the stress distribution. Four hybrid composite materials; Indirect resin composite (IRC), Resin nanoceramic (RNC), Polymer infiltrated ceramic (PIC) and Zirconia-reinforced lithium-di-silicate (ZRC) were divided into two subgroups for NT ( n  = 20) and fracture test ( n  = 40). Statistical analyses were performed with independent t -test, ANOVA and post-hoc Tukey tests ( p  ≤ 0.05). The highest hardness, elasticity and fracture toughness were observed in ZRC ( p  = 0.001). Frequency of vertical root fractures in RNC and IRC were statistically lower than ZRC ( p  = 0.032). Reinforced CAD-CAM ceramics revealed higher mechanical properties compared with IRC materials. The FEA model for fracture mechanism of RNC demonstrated lowest stress values and uniform stress distribution amongst all groups, while ZRC and PIC presented the highest fracture toughness.