A Review of Current Systems, Materials, and Protocols for 3D-Printed Splints, Crowns, and Dentures

To summarize and synthesize evidence-based conclusions on optimal three-dimensional (3D) printing technologies, materials, and clinical protocols for splints, crowns, and dentures.

In resin vat printing, stereolithography (SLA) offers superior surface finish, while liquid crystal display (LCD) and digital light processing (DLP) excel in speed for larger prints, with LCD providing a cost advantage. Ceramic vat printing yields clinically acceptable strength but is equipment- and time-intensive. Optimal angulation varies by application: splints (0°), crowns (150°-210°), dentures (45°-90°). A 50 μm layer height is preferred for most restorations, with dentures tolerating 100 μm. Commonly used resins employ low-viscosity monomers (e.g., ethoxylated bisphenol A dimethacrylate [Bis-EMA]) that limit stiffness and fast photoinitiators (e.g., ethyl (2,4,6-trimethylbenzoyl) phenylphosphinate [TPO]), requiring 385-405 nm curing.

Flexible splints excel in fracture toughness and impact strength; firm splints match milled wear performance. Printed crowns, while weaker than milled options, offer toughness; wear rates remain a concern. Printed denture bases vary in strength but can match or exceed conventional options; printed teeth show favorable wear resistance. Postprocessing, polishing, and bonding protocols critically influence outcomes.

Employing validated printing parameters, selecting the appropriate resin, and following evidence-based protocols allows clinicians to maximize restoration accuracy and mechanical performance while leveraging 3D printing's efficiency and cost benefits.