Ultrafast high-temperature sintering of dental grade 4YSZ ceramics: Effects on microstructure and flexural strength

Abstract

This study compares the effects of ultrafast high-temperature sintering (UHS) and conventional sintering on the microstructural and mechanical properties of 4 mol% yttria-stabilized zirconia, a ceramic widely used in dental restorations for its high strength, biocompatibility, and aesthetic qualities. UHS enabled full densification in just 5 min—a significant reduction compared to the 10-h cycle required for conventional sintering. Both methods yielded similar relative densities (>96%); however, UHS stabilized the tetragonal phase and resulted in a slight reduction in flexural strength. Microstructural analysis revealed coarser surface grains in UHS specimens, indicating distinct grain growth kinetics under rapid heating conditions. Despite the reduction in strength, UHS-sintered samples met the ISO 6872 minimum flexural strength requirement (>300 MPa), confirming their clinical applicability. These findings support UHS as a viable, time-efficient alternative for processing dental zirconia, with potential for high-throughput applications in restorative dentistry.