Enhanced mechanical performance of additively manufactured lithium disilicate glass-ceramics through β-spodumene/lithium metasilicate co-addition for dental applications

Co-addition of β-spodumene and LM enhances densification of LDGCs. • A-SiO 2 promotes LM-to-LS 2 conversion but increases porosity and defects. • β-spodumene/LM synergy boosts flexural strength and fracture toughness. • Excessive LM or A-SiO 2 reduces density and mechanical performance. • Co-addition of β-spodumene and LM improves manufacturing accuracy. Objectives This study aims to improve the densification and strength of additively manufactured lithium disilicate glass-ceramics (LDGCs) for dental restorations by introducing a β-spodumene–lithium metasilicate (LM)–amorphous silicon dioxide (A-SiO 2 )–glass system. Methods Precursor slurries with varying ratios of β-spodumene, LM, and A-SiO 2 were shaped using digital light processing and subsequently sintered without applied pressure. The resulting LDGC samples were systematically evaluated in terms of density, porosity, phase composition, microstructure, mechanical properties, fracture morphology, and molding accuracy. Results The combined addition of β-spodumene and LM significantly reduced porosity, promoted densification and crystallinity, and produced a uniform interlocked microstructure. In contrast, the introduction of A-SiO 2 facilitated the transformation of LM into lithium disilicate, but increased porosity and defects by impeding densification. The optimized β-spodumene/LM/glass ternary system achieved a maximum flexural strength of ∼332.5 MPa and a fracture toughness of ∼2.3 MPa·m 1/2 , while exhibiting hardness and elastic modulus comparable to natural enamel. Moreover, crown manufacturing demonstrated high molding accuracy. Significance The synergistic addition of β-spodumene and LM effectively enhances densification and strength in additively manufactured LDGCs, establishing a promising material system for high-load aesthetic restorations.