[Effect of triply periodic minimal surfaces structure and ceramic volume fraction on mechanical properties of polymer-infiltrated ceramic network composites fabricated by additive manufactured zirconia and resin].

Objective: To investigate the effect of triply periodic minimal surfaces (TPMS) structure and ceramic volume fraction on the mechanical properties of polymer-infiltrated ceramic network (PICN) composite and reveal its strengthening and toughening mechanism. Methods: In this study, TPMS structures with gyroid (G), primitive (P), diamond (D), and ceramic volume fraction (40%, 55%, 70%, 85%) were designed. Porous zirconia scaffolds were prepared using stereolithography technology, and resin was infiltrated into the scaffolds through a vacuum. Then, the PICN composites were obtained after curing. The bending strength, elastic modulus and fracture toughness of PICN were tested using an electronic universal testing machine, with commercial PICN as the control group. The micromorphology of PICN was observed through stereomicroscope and scanning electron microscope. The cytocompatibility of PICN was verified by using cell counting kit, live/dead cell staining and phalloidin staining. Results: The bending strength values of PICN with different ceramic volume fractions ranged from 82.0 MPa to 376.0 MPa, and they gradually increased as the ceramic volume fraction rised. The elastic modulus values of PICN with different ceramic volume fractions ranged from 12.1 GPa to 56.1 GPa. The fracture toughness values of PICN with different ceramic volume fractions ranged from 1.7 MPa·m^1/2 to 6.5 MPa·m^1/2. The bending strength of 85G PICN reached 306.0 MPa, and it had the highest fracture toughness (6.5 MPa·m^1/2) and an appropriate elastic modulus between that of the control group and that of enamel. Under scanning electron microscopy, it could be observed that the cracks branch and deflect at the interface and eventually terminate within the resin phase. After co-culture with PICN, the survival rate of mouse fibroblasts exceeded 80%, indicating that PICN had no cytotoxicity. Conclusions: The PICN composite with TPMS structure can satisfy the mechanical properties and cytocompatibility of dental prosthesis.