3D-printed definitive dental restorations: permanent resins, mechanical performance and clinical evidence

Additive manufacturing has moved from diagnostic models and provisional prostheses toward the fabrication of definitive dental restorations with printable resins marketed as permanent. This narrative review synthesizes the evidence on these permanent resins, their mechanical performance and their clinical outcomes. Searches of OpenAlex, PubMed and Crossref, restricted to 2015 through 2023, were organized into four thematic axes: materials and technologies, mechanical performance, aging and biological properties, and clinical evidence. Forty-five studies informed the synthesis. Vat photopolymerization with filled resin composites is the dominant route, and printed permanent resins approach, without reaching, the strength of milled resin composites and ceramics; layer thickness, build orientation and post-curing modify these properties. Thermocycling and water storage degrade strength, wear and color stability more in printed than in milled materials, and residual monomer release depends on adequate washing and post-curing. Marginal and internal fit are clinically acceptable, but clinical evidence is scarce: randomized data exist for primary-tooth crowns and complete dentures, whereas long-term survival data for printed permanent resin single crowns in adults are absent. Printed definitive resins are promising for single-unit and implant-supported restorations, yet clinical adoption outpaces the evidence. Standardized material classification, fatigue testing under common protocols and prospective clinical studies with survival endpoints are required before these resins can be recommended without reservation.