Study of fracture and fatigue resistance of monolithic zirconia dental crowns fabricated through a novel material jetting technique

Additive manufacturing is becoming a promising method for dental applications. The advanced customized jetting technique, one of Material jetting (MJ), is a newly introduced additive manufacturing technique that can produce high-accuracy zirconia restorations. However, the fracture and fatigue resistance of monolithic zirconia crown fabricated with MJ is still unknown. One hundred and twenty monolithic zirconia crowns were fabricated using subtractive manufacturing (SM), stereolithography (SLA), and MJ techniques. The crowns were subjected to cyclic loading for 1.2 × 10 ⁴ , 1.2 × 10 ⁵ , and 1.2 × 10 ⁶ cycles, simulating clinical use over several 2 weeks, 6 months, and 5 years, respectively (n = 10 per group). After cyclic loading, the crowns underwent static loading tests. Both the initial fracture load and the complete fracture load were recorded. Fractographic analysis was conducted via scanning electron microscopy on fractured parts from each group. The initial fracture load for the SM group was significantly higher than that of the SLA and MJ groups ( P  < 0.05). The 3 groups demonstrated similar complete fracture load before fatigue loading. After 1.2 × 10 ⁴ and 1.2 × 10 ⁵ cycles, MJ crowns exhibited the highest complete fracture load. After 1.2 × 10 ⁶ cycles, SLA crowns showed the lowest complete fracture load values. Fractography analysis revealed minimal defects in the SM group, while the SLA and MJ groups exhibited varying degrees of pores, inclusions, and delamination. This study indicated that MJ can fabricate zirconia crowns with reliable mechanical properties in 5 years of in vitro simulation.