Fatigue Survival of Lithium Disilicate, <scp>3D</scp> ‐Printed Composite, and Injection‐Molded Direct Composite Veneers

OBJECTIVES: To evaluate and compare the fatigue performance of veneers fabricated from lithium disilicate, 3D-printed resin composite, and injection-molded direct resin composite under standardized cyclic loading. MATERIALS AND METHODS: Thirty extracted human maxillary central incisors (n = 10 per group) received standardized veneer preparations. Veneers were fabricated using CAD/CAM milling (lithium disilicate), additive manufacturing (3D-printed resin composite), or injection molding (direct composite). Specimens were adhesively bonded following manufacturer protocols, thermocycled (10,000 cycles) and subjected to cyclic fatigue loading (200 N, 1.6 Hz) for up to 1,000,000 cycles. Fatigue survival was analyzed using Kaplan-Meier and log-rank tests. RESULTS: Significant differences in survival distributions were observed (p < 0.001). Lithium disilicate showed the highest fatigue performance, with 80% survival at 1,000,000 cycles and a mean survival of 954,060 cycles. 3D-printed resin composite showed the lowest survival (mean: 134,878 cycles), while direct resin composite exhibited intermediate performance (mean: 460,453 cycles). Failure modes varied by material, with lithium disilicate demonstrating debonding, 3D-printed resin presenting multiple failure types, and direct composite limited to incisal fractures. CONCLUSIONS: Lithium disilicate demonstrated superior fatigue performance compared with resin-based materials. Injection molded direct composite performed better than 3D-printed resin composite with more repairable fractures. CLINICAL SIGNIFICANCE: Although lithium disilicate restorations remain the most durable material choice for anterior veneers, injection molded direct composites offer an economical option with possibly repairable fractures.