Influence of printing orientation on the manufacturing accuracy and functional properties of multi-material inkjet-printed complete dentures.

OBJECTIVES: To evaluate the influence of printing orientation on the manufacturing accuracy, mechanical behavior, tooth-base transition, surface characteristics, and early Candida albicans adhesion of multi-material inkjet-printed (IJP) complete dentures. METHODS: Multi-material IJP complete dentures and specimens were fabricated at 0°, 45°, and 90° printing orientations. Baseline tissue-surface manufacturing accuracy and short-term storage-related dimensional changes were evaluated using 3D deviation analysis. Mechanical properties, interfacial shear performance, fracture morphology, and surface roughness were assessed at baseline and after up to 28 days of artificial saliva storage. Baseline wettability and surface free energy, together with early Candida albicans adhesion and biofilm formation, were also assessed. RESULTS: The 0° orientation showed lower tissue-surface RMS deviation and surface roughness, greater wettability, higher initial flexural and tensile strengths, and lower early Candida albicans adhesion and biofilm biomass. Tensile failure occurred within the bulk material rather than at the tooth-base transition, while interfacial shear strength varied with printing orientation and storage duration. After 28 days of artificial saliva storage, the 90° orientation showed the highest remaining flexural strength, whereas the 0° orientation showed the greatest reduction. CONCLUSIONS: Printing orientation is an outcome-dependent parameter for multi-material IJP dentures. The 0° orientation favored manufacturing accuracy, initial mechanical performance, surface smoothness, and lower early Candida albicans adhesion, whereas the 90° orientation showed higher flexural strength retention after 28 days of artificial saliva storage. Orientation selection should therefore be tailored to the prioritized laboratory performance outcome. CLINICAL SIGNIFICANCE: Orientation control is an important consideration in IJP complete-denture fabrication because it affects tissue-surface reproduction, initial mechanical strength, short-term storage behavior, surface quality, and early fungal adhesion. These findings provide practical guidance for optimizing the printing process and establish a basis for future clinical validation.