Additive manufacturing is increasingly integrated into dental technology, yet the mechanical performance of 3D-printed denture base resins remains strongly influenced by printing orientation and post-curing duration. This study evaluated the combined effect of three printing orientations (0°, 45°, 90°) and three post-curing times (30, 45, 60 min) on the flexural strength and surface microhardness of a denture base resin. Specimens designed in Blender and fabricated using NextDent Denture 3D+ resin were subjected to three-point bending tests (n = 5 per group) and Vickers microhardness measurements (n = 10 per group). One-way ANOVA assessed main and interaction effects. Printing orientation had a significant influence on flexural strength, with horizontally printed specimens exhibiting the highest values, whereas vertically printed specimens were consistently weaker. Post-curing time did not significantly affect flexural strength within any orientation. In contrast, microhardness increased progressively with longer post-curing durations, regardless of orientation, indicating continued surface polymerisation. Because flexural strength and hardness responded differently to curing duration, no single post-curing time was universally optimal; however, 0° printing consistently produced the strongest specimens for this resin–printer system. This trade-off is clinically relevant, because dentures require high flexural strength to resist fracture and sufficient hardness to minimise wear.

Provisional fixed partial dentures represent a critical phase in dental treatment, necessitating heightened mechanical durability, particularly in comprehensive and extended treatment plans. Strengthening these structures with various reinforcing materials offers a method to enhance their resilience. Utilizing a three-point testing methodology on standardized trial specimens allows for a comparative assessment of various materials and reinforcement techniques for pre-prosthetic applications. This study aims to validate and assess the significance of integrating different reinforcing materials into standardized test bodies. The study focuses on test specimens comprising three types of unreinforced laboratory and clinical polymers for provisional constructions (n = 6)—heat-cured PMMA (Superpont C+B, Spofa Dental, Czech Republic), CAD-CAM prefabricated PMMA (DD temp MED, Dental Direkt, Germany), CAD-CAM printing resin (Temporary CB Resin, FormLabs, USA), self-polymerizing PEMA (DENTALON plus, Kulzer, Germany), light-polymerizing composite (Revotek LC, GC, Japan), and dual-polymerizing composite (TempSpan, Pentron, USA). Additionally, laboratory polymers are evaluated in groups with five types of reinforcing filaments (n = 15)—Glass Fiber (Fiber Splint One-Layer, Polydentia, Switzerland), Polyethylene thread (Ribbond Regular 4.0 mm, Ribbond Inc., USA), triple-stranded chrome-cobalt wire for splinting 015″ (Leone S.p.a., Italy), Aesthetic ligature wire 012″ (Leone S.p.a., Italy), and Glass Fiber coated with light-cured composite 8.5 × 0.2 mm (Interlig, Angelus, Brazil). Analysis of the data using Generalized Linear Models (GLMs) reveals that the experimental bodies, produced via the subtractive digital method using PMMA (DD temp MED, Dental Direkt GmbH, Germany) as the polymer and glass filaments as the reinforcement, exhibit superior mechanical properties, particularly when pre-wetted with Interlig liquid composite (Angelus, Brazil).